DIY mass spectrometer measures potassium in dietary salt substitute

[@Direkin]

Previously on Applied Science: "I would have used a mass spectrometer, but I haven't built one yet". And here we are.

[@farvatron]

That's too good!!! Now I want a timestamped url link whatsit! lol LOVE this channel!

[@farvatron]

@@Stefan_Kawalec legend! :)

[@talesdemidioful]

You are above the pH

[@WilWinston]

I believe you are correct that the large peak is the 39 M/Z and the shoulder on the front of the peak is the 41 M/Z I am a retired Field Engineer from one the worlds largest manufacturers of mass spectrometers. Your mass spec resolution of about 2 M/Z is very impressive. you may increase your resolution by replacing the source 'side shields' with small magnets on either side (most of our sources utilized magnets in the source in this manner to increase the beam focus) The small peak at a calculated M/Z of about 47 it is likely CO2 from an air leak. In troubleshooting ms systems the CO2 peak was a ubiquitous signature of an air leak. Building a GC or HPLC front end is a walk in the park compared to a mass spec. I I can supply you with some components at 'cheap-to-free-prices' if you are interested.

[@hedgeclipper418]

This sounds to me like the simplest explanation, but do you really think the CO2 peak at M/Z = 44 could be observed all the way over at M/z = 47 when the K+ peak was pretty much dead on at M/Z = 39?

[@nickmo439]

We need videos on that topic ASAP 😉

[@hedgeclipper418]

@Miroslav Kašpar I have the same question. Seems unlikely, but at the same time CO2 is really the simplest explanation.

[@wurrzful]

I would guess that CO2 is indeed the explanation. the fact that it is not spot on like the potassium is likely due to the potassium-specific massage of the constants in the formula. I'm sure you could massage things so that both CO2 and potassium fit nicely, which actually would be a rather nice calibration for your device :)

[@__shaun__]

perhaps co2 produced by filament burning itself/sample?

[@thethoughtemporium]

I like how we all joked that you'd said "yet" in the tennis ball video when you mentioned mass spectrometers. And now you've gone and done it! Amazing. Been wanting to do this for years but the difficulty and tedium to constantly take it apart and put it back together always scared me off it. I think in a couple years I may end up building one now! Though I'm excited to see the follow up you mentioned. Quadrupole? Some RF magic? Lots of ways to make a mass spec, so I'm stoked to see what you choose. Have you picked up a copy of "building scientific apparatus"? there's a whole section on mass specs. As to the 47mu peak, what about titanium? titanium dioxide is known to be a filler in salt products. It also has 1 common isotope at exactly the right spot, and then 2 much less common heavier isotopes and 2 lighter isotopes. Peak would look similair. If this can't resolve the potassium peaks I bet it can't resolve the titanium peaks well either so they get glomed together.

[@noahhounshel104]

I might actually lean towards the idea that it's Titanium, if it's possible to actually get a sample of this looked at by a real spectrometer it would answer whether or not it's just a ghost really easily!

[@Muonium1]

@@noahhounshel104 Well he built his own scanning electron microscope, so now he can just build his own EDX energy dispersive Xray element analyzer to add on to it!

[@measl]

*A birdie?*

[@irvincoria1887]

What are the odds that in all 3 experiments the KCl salt used had the same ratio of titanium to potassium? I don't think that is very likely.

[@eelcohoogendoorn8044]

Feels like too much titanium; according to the ingredients such flowing agents tend to be less than a percent.

[@TechIngredients]

This was very well done and very enjoyable to watch. You have to be near the top of the list of people that will never, ever, ever give up! Cheers

[@corlfranco9371]

loosing his sanity for us

[@yetanotherPC]

Well this makes sense! I see the many similarities between your channels

[@svchineeljunk-riggedschoon4038]

Hi! :)

[@kev4241]

no doubt, perfect for experimental physics

[@VoidHalo]

You could easily say this about every video on this channel. This is one of the few (or only) channels that's never had a video I didn't enjoy. Even for topics I'm not that interested in, the video usually piques some level of curiosity by presenting it from an applied point of view, rather than the school approach of saying "it works this way, just take our word for it". Before they trust you with labs, anyway. And the videos are so information-dense you can watch them 5 times over and still learn new things, as I did with this one just now.

[@ScrapScience]

Measuring sodium might be a good way to check whether that second peak is just an echo. Sodium pretty much just has one naturally occurring isotope, so if you see a second peak that would confirm your theory of there being some kind of echo artifact.

[@charliesteiner2334]

Yeah. Or even easier, what happens with potassium if you shift the DC voltage? Does the mystery peak shift correctly? 47 amu is something like Titanium, or maybe SiO, or Tungsten 4+, so not totally impossible.

[@sophiophile]

"....That would support* your theory...". FTFY.

[@Mainzbas]

i would also suggest to measure a tin or barium compound because they have a lot of stabil isotopes, so you could test your separation and get an idee if the shoulder of your peak for the Potassium is the second isotope. To get an idea of the ratio of isotopes maybe it would be better to count the area of the signals instead of the height?

[@cogoid]

As _WilWinston_ has pointed out in his comment, most leaky vacuum systems show a CO2 peak, which has m/e=48. Such mass spectra are most commonly seen not in "real" mass spectrometry but in RGA (residual gas analysis) which is a specialized from of mass spectrometry for troubleshooting vacuum systems and process equipment -- there you ordinarily look at all the usual contaminants from the atmospheric air, absorbed water, etc.

[@bobsagget823]

@Jeff Sweeney wrong

[@jrrymiller]

SA did an Amateur Scientist gas chromatograph "The Amateur Scientist How to construct a gas chromatograph that can measure one part in a million By C. L. Stong" September 1967 I was festinated by your presentation.

[@mattshilling]

That’s awesome. I really need to go back through these Amateur Scientist articles, seems like they’ve got some sweet projects I could work on.

[@rickfreeman5866]

@@mattshilling Hi Matt, I remember one of these articles that measured 'proton precession', the basis for today's MRI medical scans. My friend performed that experiment while I built a binary adder out of WW2 surplus relays, switches and pilot lights.

[@dmsaintrain]

Also, "How to Build a Gas Chromatograph and Use It to Separate the Components of Mixtures", Stong, C. L., June, 1966.

[@bdnugget]

You can buy gas sensors for under 20 bucks like the TGS-813 for example. Making a chromatographic column for gases is also fairly simple, just take some plastic tubing and fill it with sillica or even more ghetto and oldschool, bentonite clay from kitty litter. Flow a carrier gas through it, which can just be air from a cheap aquarium pump and inject your sample in there. The real problem in GCMS and LCMS is interfacing it with the MS, since the MS operates under high vacuum and your LC or GC operated in solvents or gases. In LCMS it commonly get's nebulized and shot past a tiny ESI pipe which goes to the MS, and because that's under vacuum, it sucks some of the spray into the MS while the majority just goes to waste. Maintaining vacuum this way requires a good pump.

[@noahmccann4438]

5:16 “Nothing is an impossibility, so we try to do the best we can” - that is remarkably inspirational

[@AppliedScience]

Yeah when I said it, I was thinking that nothing = lack of anything (a perfect vacuum), but, yes it has a few different interesting levels of interpretation.

[@Jimmeh_B]

@@Styrofo4m Ironic, that you chose your handle.

[@evilcanofdrpepper]

@@AppliedScience Talk to the guy who runs the KZbin channel Thought Emporium, he makes tons of scientific equipment from scratch on the cheap. He created a cheap Gel Electrophoresis and doc for it and I know that it's not a chromatograph but I bet if the two of you start talking about it you could create one in under a month. He has more of a focus on Biology though but Im sure he could make use of a Chromatography station if he had one. Same goes for a mass spectrometer now that I think of it lol. Speaking of it, can we see what shows up when you run a bare tungsten electrode in it without anything else to see if something about those parts is putting extra ions into the system to cause the smaller bump? Something tells me that Scientific American never thought that anyone would ever actually try to build one of these mass spectrometers. I hope with help and ideas from everyone we can get it working better. I was thinking about covering the end of the rubber stopper with something in an attempt to lower the off gassing but I don't know what would be better. Keep up the unintentionally awesome inspiration and keep making awesome things! here's a link to the video on his Gel Electrophoresis video to make things easier if you don't already know who I'm talking about. kzbin.info/www/bejne/qYSunaZooLN2arc

[@noahmccann4438]

Miroslav Kašpar yes, as he mentioned above. I did understand the original intent, I was just also implying that it could be interpreted as an inspirational message.

[@calholli]

lol.. 'nothing' meaning absolute zero-- that's what he meant

[@IanJohnstonblog]

I wish there was a “I couldn’t love this more” button on KZbin.

[@S-K.]

Favorites! I think favoriting videos can affect the outcome/publicity a video gets!

[@devinslurry365]

You should change your name to ion Johnston. Surely that would boost your resume at the least.

[@rkan2]

Probably what Patreon can be used for..

[@chemwahoo]

Some fun vacuum tips from a spectroscopist who has lived in HV for the last decade or so. The rubber/PVC limitations you were seeing are likely not due to the hose clamps; I've achieved 1E-6 to 1E-8 using similar materials in a pinch. The main issue is the both absorb water like no tomorrow. The rubber stopper didn't noticeably affect the system [as much] because its higher density, lower surface area as is likely nitrile. Most soft plastics (teflon, soft pvc, vinyl) are also *very* permeable to atmospheric gases. The 1E-4 vaccum limitation is likely due to a combination of two things. 1. (less likely)small imperfections in solder joints. If you have a decent gague you can check for this by spraying a light gas(He) or methanol on the solder joints and looking for the gauge to bounce. 2. (most likely) Water. Copper *loves* water. You said you are having the break the seal every 5 min or so which is instantly recoating the surface with water each time you do. Typically with our [Steel and Al] chambers first pumpdowns can take between an 30 to overnight to get past 1E-4 depending on heating/pumping speed. Subsequent pumpdowns are much faster. Not using copper, letting a dry purge gas flow between vents, or installing a butterfly valve between the ion chamber and main vacuum line would all drastically help. (Oh also the rubber stoppers are going to be a huge source of water). TL;DR water is evil.

[@materialdialectics]

I'm not sure there's a word to express how impressed I am by this. You take DIY to a whole other level.

[@rusticagenerica]

You can say "STUPENDOUS" or "SURREPTITOUS".

[@William_Hada]

I would love to build one of these! Awesome video! The clear PVC tubing has lots of phthalate plasticizer oil in it which is relatively low molecular weight and would volatilize easily under such low pressure. The black rubber has no plasticizer and is highly crosslinked to to point where it is essentially one giant molecule

[@Richard.Andersson]

Different rubbers also absorb moisture or other volatile chemicals more or less easily, which will evaporate in the vacuum later on. Hence the type of rubber is also important. (Also the filler in the rubber plays a roll)

[@janami-dharmam]

"The black rubber has no plasticizer and is highly crosslinked to to point where it is essentially one giant molecule"- in that case it will be hard like a rock and practically unusable.

[@paulmoir4452]

@@janami-dharmam The scar on my face which was partly caused by the ductility of UHMW would disagree. (Also, a comment only to be found on this channel.)

[@emilychb6621]

@@janami-dharmam Huh? You can make rubber without seperate plasticiser molecules easily. The 'plasticiser' would be part of the rubber polymer.

[@emilychb6621]

And even giant molecules can be 'soft'.

[@jonwnye]

I use IRMS nearly everyday in the lab, but seeing a homebuilt one with an excellent explanation is great. Gonna show this to pretty much everyone who asks what I do for a living. Would love to see a a GC setup in a similar vein.

[@RB9522]

I built a Liquid Dye Pulse Laser based on an Amateur Scientist article in about 1970. As far as I'm concerned, you are the New Amateur Scientist!

[@twn10]

Richard Burgan Hi, can you shed some light to us how you built the laser? Amazing thing.

[@homosapiensqp3225]

.

[@RB9522]

@@twn10 The article is in February 1970 Scientific American. C. L. Strongs column "The Amateur Scientist". It might be hard to obtain the quartz glass parts that were available as a kit for a while right after the article's publication.

[@teresashinkansen9402]

@@twn10 You can go to Sam's laser FAQ to learn more about them, and there is Yun Sothory's excellent website about scratch made lasers out of easy to get materials, with his instructions i made my first flash lamp pumped dye laser. You can also make a relatively easier but much less powerful dye laser by first making a nitrogen TEA laser and then pumping the dye with it, just be careful tho this pulsed lasers look cute and inoffensive but will blow a hole right thorough your retina quite easily. www.repairfaq.org/sam/lasersam.htm laserkids.sourceforge.net/

[@ericcodner7627]

We built a mass spec based on the Dewdney paper in my intrumentation class about 10 years ago. We also saw a double peak but since the machine went together literally minutes before the end of the semester we simply accepted the idea that the peaks represented the two isotopes. There are two GC articles in the complete Amateur Scientist collection CD-ROM. The gas flow through both designs is quite a bit higher than an MS detector will accept.

[@BRUXXUS]

I love the fact that with enough time and dedication pretty much anyone could just.... you know, build their own high tech lab equipment. Does this work perfectly? Not really, but the fact it's detecting anything even near the expected result is just incredible.

[@TheCarterhcole]

With the right foresight with designing the vacuum line, its easy to use a diff pump where you need to frequently release vacuum. If you put a stopcock between the diff pump and the working line then you can close off the pump to the line, release the vacuum, and keep the diff pump refluxing. This way you can do whatever work you need and then reopen to the diff pump and it should pull down within minutes. You can keep a diff pump refluxing 24/7-365 as long as youre not pulling shit into it and keep it under vacuum (if you heat the oil under atmosphere it will char). Mine has been running for ~3 years continuously with no maintenance (though the roughing pump sees regular oil changes). Cold trapping also helps, but I have cheap and abundant LN2 so thats probably not worthwhile. Never used a turbomolecular pump so I cant comment on whether this is "better" or not, it's just what I have access to Not sure if this is already known to you, but thought I'd chime in as a chemist who works on highvacuum lines frequently :) I'm also a bit surprised that you had such large issues with tubing. I am able to maintain 1x10-6 torr with tygon tubing segments (rest connected with ground glass or o-rings). Definitely out to low millitorr you should be able to use clamped tubing (most schlenk lines in chemistry labs feature tubing similar to what you used, and 50mtorr is achievable on a good line--and that is pump limiting not leak limiting)

[@CafeBikeGirl]

He should be able to hit -5 torr with that turbomolecular pump in about

[@excitedbox5705]

@@CafeBikeGirl diffusion pumps are much higher volume though than turbo pumps per size. I have seen videos where the gauge plummets like a rock when they open up the diffusion pump and that is on a much larger chamber than that little pipe. Problem is that out-gassing is not free flowing gas so it takes time. To get lower he would also have to do a bake out to get rid of humidity.

[@CafeBikeGirl]

No doubt that a bake out will help clean out all the crud in the system from initial assembly and make sure he's not getting stray signals from stuff outgassing but it's a molecular flow system, he's not going to get any more flow than what that KF25 connector allows which is going to be something like 30 or 40 liters per second. The pump he's using appears to be comparable to 140 l/s pump (for N2) Even then the analyzer portion is not going to flow any more than the ~1/2" T-fittings allow. Unfortunately his sample delivery isn't going to support doing a bake out during a measurement run but he should be able to squeeze out another order of magnitude on the vacuum with a little effort. My real point was that for $20-40 he could significantly reduce a potential source of gas load, and to your point if he hasn't done a system bake out yet that could reduce it some more without adding complexity. Backfilling with nitrogen would be a big help but he would need to add a valve for that (preferably two) and be very careful not to shock the turbo. These things would get him more working time with his sample.

[@maartenaerts2344]

@@CafeBikeGirl & ​ @excited box I truly enjoy your discussion above, as well as some other interesting notes above. I believe I can even follow, though it's 'not quite' my area of expertise. Of course, thanks to @applied science for an excellent video and a beautiful build!

[@jamesbrown99991]

To rule out differences between forward and reverse scanning directions, you could use a sawtooth deflection voltage. This will remove the reverse direction almost completely.

[@devrim-oguz]

Exactly, like raster scan

[@MrRolnicek]

Or ... his oscilloscope looks fairly smart. if it can output data in real time (or record and output later) you could literally separate the graph into lines drawn by the sweep in one direction and the lines drawn in the other direction. Depending on his setup he might be able to do that for the already made measurements.

[@whitcwa]

A sawtooth would also provide a linear sweep instead of the sine wave sweep.

[@__dm__]

Getting that to work just right in his system where he uses a transformer in series with the signal is going to be a bit challenging...

[@jamesbrown99991]

@@__dm__ Why is it challenging?

[@CuriousMarc]

Fantastic work as usual. From the time when Scientific American was the most awesome science journal, written by actual scientists for people that really wanted to understand things. Like viewers of this channel for example. Oh, do I miss it. Now it's a sad ghost of its former self.

[@Rangeldangeldodo]

Razer blade slits - classical DIY solution in optics... love it!

[@pabloascencio7397]

about the thickness of a razor blade, made from razor blades

[@christianh2581]

Amazing work! I just want to add that it is possible to analyze substance mixtures even without a gas chromatograph (As Ben has said there are a lot of different MS techniques). To do this the molecules are ionized with less energy, such that they do not break apart into the individual elements, but instead such that different sub-parts stay together (like CH3, CH2, OH and so on). This gives a fingerprint for each molecule. With those fingerprints (relative peak height for the different masses) you can assemble a system of linear equations. Then you analyze the substance mixture, you solve the system and you get the proportion of each substance in the mixture. Also there are spectrometers that have a gas-inlet, which allowes to analyze gas mixtures continuously. This can be used to monitor chemical reactions in almost real time.

[@jimaspinwall7814]

I used to service both quadrapole and magnetic sector mass specs - one way to learn science and chemistry backwards. Freaking impressed you built this at home... "in the backyard" of two infamous mass spec makers - Finnigan and HP!

[@lb7325]

Good on ya Jim. Maybe he can add an argon plasma interface to make things really interesting. I'm a retired mass spec tech/engineer

[@HappyMathDad]

Scientific American, the favourite magazine of my youth. The first thing was to go to the very end and read amateur scientist and mathematical recreations. Then read the rest. I just loved it. And it's so cool to see it referenced here. Hats off!!!!

[@RichardKinch]

"I'm going to show you how to build a mass spectrometer in the home shop." [*Proceeds to produce a turbomolecular vacuum pump from yard sale junk pile.*]

[@aliabbas-ps4ii]

You are amazing... I'm a service engineer and have worker with several mass systems from Agilent, thermo, Shimadzu... but to see some one building a mass unit... thats astonishing

[@TheNefastor]

That Tek scope alone is worth more than a BMW...

[@schmetterling4477]

@@TheNefastor And you can do the experiment just fine with a $20 Amazon scope kit.

[@AureliusR]

@@schmetterling4477 I strongly doubt that, they don't have the resolution or bandwidth (or voltage handling) to do something like this.

[@schmetterling4477]

@@AureliusR Yeah, they do.

[@henrikstenlund5385]

This is very interesting, thanks. Long time ago I was supposed to develop a mass spectrometer to a company. After initial research I totally rejected the magnetic system as big and bulky and expensive. Then I built and tested several time-of flight mass spectrometers. The first ones were of traditional straight type where ions were sent to the other end with an MCP sensor. The mass resolution was not satisfying. The next step was to add an electric ion mirror replacing the MCP shooting the ions back through the ionizer . The ionizer was using mesh windows and controlled voltages to allow/prevent ions in their travel. On the back side of the source was the MCP detector. The voltages and dimensions were optimized to sharpen the resolution to over 4000. This was successfully verified by measurements. The sensitivity was very good and the whole system was about 500 mm in length and rather simple and reliable. The time scale was in the range of 200 microseconds max.

[@tihzho]

Amazing work! Judging from the size of your turbo pump the level of vacuum is only that pump is able to keep well ahead of the leaks and outgassing! Copper outgasses a lot (oxygen free copper is better), aluminium brass or 304 stainless steel would be a lot better! The solder is not that much a worry but the flux is. I used to work on this stuff........god 35 years ago!!

[@CafeBikeGirl]

Yea, I'm sure his pumping speed is whatever a KF25 will provide at that temperature and the little copper T-connections on the analyzer. I'm curious how he obtained one that big for "home use" in operational condition.

[@cortez3001]

Ben, you are such a genius, man! I've seen some really elegant and enlightening 'do it yourself' solutions in your channel. Thank you for making it available to the world! As you talked about the comment section, I felt encouraged to share an idea I had a long time ago, that I've never researched on how to do it for - I have to admit it - lacking just the type of knowledge that you've been showing to have. I think most DIYs people are like me, having a basic understanding of electronics, how to make PCBs, how to follow instructions, etc. But to materialize more sophisticated ideas is something else... So, since I believe the idea is useful, on behalf not only of myself, but the rest of us, DIY enthusiasts, please, teach us how to make the following: A device able to power other unmantained devices with an output of 500 Watts or less for extended periods of time (say, every year), when fuel cells and batteries can't possibly do the job and for places were fossil fuel generators, solar cells, wind and geothermal power can't be used or, for whatever reason, are not feasible. Some examples I can think of: underground or underwater measurement devices, underground shelters with refrigerators, energy safeguard for cave exploration, marine biology monitoring, underground panic rooms, and so on. I'm aware that one thing that would suit such requirements would be a radioisotope thermoelectric generator, but it doesn't seem to make any economical sense, probably not even being achievable in an amateurish DIY scale...

[@hanabihanabi1060]

Hi. Been watching for sometime now and I like your channel. I have worked with mass specs for a long time even designed magnetic sector and crossed E-B field devices. Most of my work has been in residual gas analysis. I think I can help with two of your issues, which were present in the earlier work. 1) Try a pin hole not a slit. The slit is fine for optics but with your variable mag field the slit is sending a flat ribbon-ish stream of ions which pass thru different mag fields reducing your resolution. You may also be defocused and with the variable field you could have distortion which creates multiple images at different energy levels producing the ghost peak. Again a point source will help as will a more uniform mag field. 2) If you scan the energy slowly the input capacitance disappears in your charge / current amp. When you deliver a pulse of charge, the amp is acting more as a charge amp. The gain of a charge amp is Cf/Cin, or Rf/Ri whichever is smaller. By going to a DC measurement you remove the pulse nature and hence measure current. We used to use Keithly 602 electrometers. 3) I have suggestions for mods to your ion source and adding a focusing element after could also give you much better results. Niether of these is difficult. Einzel lenses are very easy to design and build en.wikipedia.org/wiki/Einzel_lens. 4) I await your time of flight mass spec, I was on a team that flew one to Hally's Comet once a long time ago, in a galaxy far... Hanabi

[@jackmclane1826]

One of the most underrated contributions in a YT comment section! I also agree on the first point. ;)

[@hanabihanabi4728]

@@jackmclane1826 Thank You for your kind words. Ben kind of put out a teaser on a different kind of mass spec, which I presumed was TOF. These are easy to build, but do not have much resolution. On the Haley's comet device, an instrument on the European spacecraft to the comet, we used a tungsten impact plate. At 70 km/s the dust grains would vaporize on impact. We used a PMT to detect the flashes (our part of the instrument) and set 0 time, then an electrostatic field extracted the ions and accelerated them towards an electron multiplier which detected the ions. From F=m*A you could extract the ion's mass/charge ratio with tungsten as a calibration standard mass. Fun days those!

[@ThunderDog]

Applied Science video = turn off everything that could be remotely related to a distraction and try to follow along with a pure genius. Love this channel!!

[@henrydane6702]

As a physics undergrad student I find a lot of your work fascinating, especially this. Your ability to keep your videos focused on the scientific work, in conjunction with your attention to detail makes for really engaging content. I am very much looking forward to future mass spectrometer content. Keep up the spectacular work.

[@johnmcclain3887]

I have to say, I had no expectation of running into this tonight! I've watched another guy use a "gas chromatograph mass spectrometer" many time, as a Marine, with oil samples for the engines and transmissions of helicopters, if the metal content is high, it was time to tear down and rebuild, rather than wait for it to blow. I'm very impressed with your work, and what you've put into it. As to the rubber plugs, the answer is "carbon black". I've been a mechanic all my life, in and around nasty equipment, but the dirtiest job I've ever had was at a couple of tire shops, for a couple months each. By the second day, I was gray, stayed gray for three or four weeks after moving on to another job, electronics once, and the Corps the first time. Carbon black plugs any holes, and those plugs are long enough it simply packs in. I worked on big 200 KW diesel generators for a while, and they produce a good bit of particulate carbon of that minute scale as well. Thanks for a great job, a great demonstration of talent, patience, and industry. I've got to watch my dietary intake very carefully because of multiple sclerosis, gulf war disease, from our classified, experimental anthrax vaccine, back in 89, so this is extremely interesting to me, potassium is what I'm always concerned about. Incredible!

[@samykamkar]

Yes!!! Have been looking forward to this video, and so appreciate the post-validation breakdown.

[@robmckennie4203]

but most of all, samy is my hero.

[@worldgeektube]

This was just fabulous. Explaining how a mass spectrometer works was great in itself and then talking through the engineering challenges of actually making one was fascinating. Finally, noticing the apparent problems in the data collected and suggesting an explanation. True science, wonderful teaching. Subscription renewed.

[@StreuB1]

You are using a commercial light bulb filament as an electron sprayer. The filaments as well as the envelopes of commercial bulbs have additives and one in particular is used for oxygen scavenging. What you are likely seeing in the 104v return is zirconium which is used to scavenge minute free oxygen atoms.

[@monster2slayer]

Zirconium has a mass of 91 amu. Even if it were doubly charged that would get you to m/e 45.5. Also the isotopic distribution doesnt look like zirconium at all

[@togirachetowa]

I was barely able to follow your explanations. It's astonishing to me that you can apply knowledge from so many different areas to a real world problem. Hats off. I really wish I could achive such a deep level of understanding science.

[@AshkanKiani]

It would've been nice to see another graph with a different compound to see if the same mirroring effect existed. That would probably be the strongest evidence. As another commenter mentioned, it could just be another ion (such as Ti) present. So if another graph presented a peak at 104V, then it may not be mirroring, but another ion. Whereas if the position were slightly different, it could be the mirroring you mentioned. If you could come up with a compound which would present a more unique double hump of two distinct peaks, then I imagine it would be the strongest candidate. But, then again, I don't offhand know of any solution you can make with two dissimilarly weighted elements (but I'm not a chemist).

[@yayforfood100]

@@Vallecaucanisimo I believe it was around 47, which would make it titanium

[@PaulHigginbothamSr]

You know, I enjoyed your rebuild of a second stage -100 degree beaker cooler. That was probably the best thinking and explaining of any refrigeration video I have ever seen. It was replete with first principals all the way through. VERY good job there Monsieur.

[@heavencloud92]

I don't have an article to link you, but a simple gas chromatograph is fairly easy to make. Generally speaking you have three parts: the sample inlet, the analytical column, and the detector. Since you already have the detector you need a closed system with an adsorbent that is temperature controlled, flow to move things through it, and a way to introduce sample. I've made columns out of 1/16" to 1/4" copper and stainless tubing packed with silica gel, molecular sieve, alumina, and so on. The stationary phase and length largely depend on what you are going to analyze. A small insulated box works for holding the coiled column and can be temperature controlled with heat tape or heater cartridges and monitored with a thermocouple. If the length and diameter of your column are small some people have simply run current through the conductive column to heat it.

[@heavencloud92]

Hydrogen vs nitrogen is tough for a carrier gas. Since nitrogen is a larger molecule the gaps between them are bigger so it's less efficient than hydrogen, but since hydrogen is so small and you're intentionally introducing it to your mass spectrometer it will really make your turbomolecular pump work. Gas purity is also of the highest importance. Hydrogen can be generated much cleaner than nitrogen can be purified so that might make a big difference. Speaking of clean you need a way to introduce the sample without letting air get into the system that would damage the tungsten filament, and without massively disrupting flow to the system. Multi position valves work well, or an injection through a pierced septum are typical. For the analytical column to function effectively the sample needs to be primarily in it's gas phase, so you want to start at a temperature where your lowest boiling point analytes will be a gas and gradually increase your temperature from there to volatilize the rest of the sample. The ramp in temperature also speeds the rate that compounds elute from the column, so you can play with that rate to get better separation between compounds.

[@johngreen4610]

I've been watching your channel for some years now. Great videos, learned much, even been inspired. I don't believe I've commented till now, no sense sticking ones nose unless one has something worthwhile to say, but something you said in this video inclined me to stick my nose in. You said that you are contemplating producing a similar video using a laser to produce the ionization. About 5 or 6 years ago while dealing with some mineralogy problems I cast about looking for some method of doing some elemental analysis. I rejected a number of methods including mass spectrometry. The method I decided upon was Laser Induced Breakdown Spectroscopy LIBS as it seemed to be the easiest to implement on by meager budget. I suspect that this is the technique you are contemplating. The system I built was surprisingly simple to build. It involved a q-switched Nd YAG laser from an outdated range finder from the M1 Abrams tank program along with the associated pulse forming network and trigger module. Total cost of that stuff, about $250. I also used a HV transformer from a junked microwave oven, a 5 amp 120 v variac which completed the laser part of the system. The original spectrometer was fashioned from some PVC pipe, a couple razor blades. and an old pre-recorded DVD. There are some limitations of a simple system like this but so far I have analyzed hundreds of samples and I am building a library of elemental spectra. I am currently working with a numismatist on analyzing revolutionary war era pennies. BTW FWIW I believe that I must have bought the last laser of this type as I can no longer find any though General Dynamics is upgrading hundreds of M1 tanks for several orther contries. If anyone knows if these may become available on the surplus market please post here. Video I uploaded years ago: kzbin.info/www/bejne/kKulhHaoiJ15d7s Ben if I can help in any way let me know.

[@nicktohzyu]

i'd really like to see that glass diffusion pump working

[@erikev]

You could easily make many of your problems go away. We built one at the university. We built one 8 meters long. The sample was in a metal box the size of a matchbox and vaporized with heat, then ionized and accelerated. It could run for weeks. A heating filament in a radio tube was used, not a lightbulb. If I recall, it was a much better electron source than what a light bulb wire can be. An electron trap catches the electrons, and the now +1 ionized sample are accelerated in a normal direction of the electron flow. The accelerating voltage was 800V. We used an electric field to cancel out the magnetic field, and varied the electric field. Also used two quadropoles to focus the beam (or maybe on to just flatten the beam for better resolution, the second would be for signal strengthening.). I would also try out using a Microchannel Plate or nightvision sensor to measure many channels. I have never tried this, but it would be fun to test even a back illuminated CCD/cmos sensor. If not a dynode. Or try out an avalanche photo diode APD with the window removed. Disclaimer: This was done decades ago, before I worked as a design engineer at Tektronix.

[@nohphd]

Amateur Scientist published TWO articles on DIY gas chromatographs, the first one was a hot wire thermal detector, the second was with a flame ionization detector. I built both in high school. Unfortunately the GC that front ends a MS usually uses a capillary column, otherwise the combination of carrier gas and sample will flood the MS. I ran a GC/Ms for a few years, get a turbomolecular pump instead of the oil diffusion pump. I still have a capillary GC in my garage. HP, not DIY. Also, you should be measuring peak area, not peak height for abundance. Wonderful and inspiring video.

[@trey1531]

He is using a turbomolecular pump. He said in the video that he ditched the diffusion pump.

[@nohphd]

Trey - au contraire Madame! @7:30 that glass thingy filled with boiling oil definitely isn’t a TM pump. He’s complaining about the time it takes to start and stop the pump when he has to reload the ion source. That butane stove he’s using certainly isn’t running any TM pump I’ve ever encountered. He did say he’d like to revisit the diffusion pump in a future video.

[@uski]

You built TWO gas chromatographs in high school ? And for all these years I foolishly thought I was doing cool stuff myself in high school...

[@nohphd]

@@uski scientific American magazine used to have an monthly column called the Amateur Scientist where they described how to make such. They had two articles on GCs, I built them both. Kind of like Instructibles today.

[@hygri]

Flippin' incredible. Few points from bitter analytical lab experience: - Regular hose clamps are a nightmare for vacuum, they create a pinch which invariably spoils your day - Find something like a Mikalor W2 clamp, use two, 3" hose over the tube and HiVac grease. - Those thick rubber tubes get tricky past about 10^-3 torr mostly due to the above, but I've had success to 10^-4 with vacuum epoxy as a sealant and the correct diameter tube. - Solder won't be a problem until silly vacuum, but the flux would make you very unpopular in any analytical lab... but definitely the perfect option for you. - Your calculations and conclusion appear correct, and that does look like noise; in the mains-provided bias voltage perhaps? - I wouldn't discount the prior spectra, their peak area looks to be very close to 6%, without knowing the details and scaling perhaps your resolution is just lower? - Try introducing CO2 into the source, it should ionise nicely and give you another peak at m/z=48 to work with, Argon is also handy at m/z=40. - It'd be really interesting to see some organic compounds, if you've got any gamma-unsaturated aryl ketones you should see some lovely parents and McLafferty fragments, Isopropanol should give you a great carbonium ion at m/z=43, most aromatics should give a radical cation and a salt of that 2,2-bipy would be spectacular. - In order to get good ionisation of organics in EI+ (and often EI-) a source makeup gas, often chlorine / ammonia depending, is used to provide a cation stream to ionise the sample and occasionally form adducts; this may be a useful technique if you have problems getting your organics to fly, if you do indeed try that (which I hope you do!)

[@chrisaa746]

The cork is likely Buna-N which a common vacuum o-ring material and it is low outgassing, the others are Viton a Fluorocarbon, and silicone - so no surprise Buna-N works as a feed thru material. The Silicone hose however was a surprise that it did not work, even with a simple hose clamp - I do use vacuum grease on the hose connector so the hose clamp does not create a fold on the inside of the hose during clamping, The charged plates for focusing the ion beam not working is interesting, perhaps electro-magnets like a crt. perhaps I don't understand, I will have to look at my RGA now Ha! I really love your videos, thank you!

[@KallePihlajasaari]

I think he said the clear tubing was PVC 6:26 and the cream tube was 'professional' vac tubing that was also wanting though he did not indicate the material.

[@chrisaa746]

@@KallePihlajasaari Yes, the white cream is likely silicone, comes in red too. I use it on my scroll (roughing) pump for the turbo and again on my diffusion pump's roughing pump as well.

[@dwinsemius]

OMG, I'm 19 seconds into this video and I'm already hooked. A copper tube mass spec to measure household ingredients. Go for it!!!! And then you cite one of my heroes: C L Strong.

[@chrome4096]

Every topic you cover just amazes me. I like to think of myself as a science and maker guy, but you have amassed soo many tools and insights that I'm just baffeled at anything you come up with. wanting to start my own channel for a while now, but apart from budgetary constraints, which can always be worked out by the help of friends I unfortunately haven't the space so far.... nonetheless keep up ypur awesome work

[@user-ri7fo6tp5e]

I wish I worked for you, and you just show me how to make ingenious things. Your production quality and teaching skills are some of the best I've ever come across. Please keep them coming!!

[@Qpwrtm]

To lower input capacity of your transimpedance amplifier and photodiode there is a technique called bootstrapping, where you put another opamp in a buffer mode over photodiode cancelling its capacity. We even used it in exomars spectrometer

[@Basement-Science]

How well does that work for very small signals? just wondering.

[@rusticagenerica]

What the hell are Exomars ? Exozomes grown on Mars ?

[@Qpwrtm]

@@Basement-Science we only use it for small signals, so it's working pretty good, sorry for 1y delay)

[@Qpwrtm]

@@rusticagenerica try google, it's a space mission

[@Krmpfpks]

This is one of the best DIY achievements on KZbin, congrats. Maybe even the best together with Jeri Ellsworth etching her own transistors at home.

[@royJohannes1]

I did my thesis on building a compact spectrometer using a CCD sensor. It was great fun.

[@DarthZackTheFirstI]

@@accord3702a he probably only build the thesis from theory ;P

[@nohphd]

accord3702a - There are multiple, open-source visible light spectrophotometers, using a cell phone, for the detector, a replica diffraction grating (an even a small piece of a CD/DVD!) and a razor-blade slit. Calibrated by old fashioned neon indicator lamps and a variety of LEDs across the visible spectrum. Google DIY spectrophotometer.

[@DarthZackTheFirstI]

@@nohphd oh thanks, i saw one of that. any idea with what i can read the time difference of the waves? never figured out how i could do that with cheap stuff if its possible at all.

[@nohphd]

DarthZackTheFirst - time difference of the waves? If I am understanding you correctly, they are not scanning each individual wave over a single detector. Instead they simultaneously detect the full visible light spectrum across the imager in the phones camera. So the pixels in the “CCD” column 17 might be photons from 550 nm and the pixels in column 2745 might be photons from 414 nm. With a couple of reference lines, you can calibrate the unit and perform meaningful spectroscopy.

[@DarthZackTheFirstI]

@@nohphd oh maybe mixed it up with interferometry.but i just see they are using a ccd camera there too. interesting stuff.

[@N1RKW]

I find this utterly fascinating. Completely over my idiotic head, but utterly fascinating just the same. Thank you, Ben, for showing us that amazing scientific apparatus is not only available to those at large research institutions.

[@timfagan1333]

I built one of these for my high school physics project. My teacher was very impressed and said that out of all the things that didn't work,mine was the best.😄 Still got a high distinction grade for it though. This taught me a lot of skills and experience in experimental science and lead to a career as a research engineer. These days kids miss out on the adventure and fun with science.

[@FetKiller]

All I can say is WOW! And I don’t think I’ve ever read so many interesting comments on a KZbin video. If it was the Ti from the blades how did it get accelerated / ionized to make it to the faraday cup? Amazing how sometimes we all think it impossible to do stuff like this at home / maker space. We are so fortunate to to have a person like Ben that is not Fing scared to fail to show us all that with some ingenuity we can do amazing things. Maybe an electrometer tube connected right to the the faraday cup inside the vacuum chamber might help ? Or dare I say an electron multiplier can get complicated in a hurry.... But I understand that there are so many variables in an experiment like this have to focus on one at a time. Thanks Ben!

[@ElementalMaker]

I need to see a video on that glass oil diffusion pump! How cool!

[@adamsapple7193]

I have no freaking clue what you are talking about, but I’m absolutely enthralled.

[@iambiggus]

'It's been days... or hours.' Lol, gotta love projects like that.

[@markheller197]

Holy cow. Those articles in the back of SA were inspiring. For that matter so are you!

[@RingingResonance]

Cool. Just don't build an anti-mass spectrometer and start the resonance cascade!

[@EpecFale]

Let me finish the HEV suit first.

[@jonpeltier5768]

So happy and grateful that you share these projects, Ben. The way you produce your videos is so very warm and inclusive. You make me feel like I'm standing right there in the garage.

[@PaulGreeve]

Brilliant! Thank you. Finally I understand how these work.

[@jonathansnow1886]

Very cool. I'm a pro at this -- I did my PhD thesis using TIMS at MIT. We literally built mass specs of this kind by hand. Far more advanced obviously with big hand-wound electomagnets and 10KV accelerating voltage. My thesis involved the isotope ratios of neodymium measured to better than 0.003% and the result got into Nature (no bs: v. 371 p57-60). Today nobody does this, all mass specs are off the shelf, and much better than I used. But this is how A. O. Nier did this in the thirties making possible the separation of the masses of uranium (you know where that led, hah, pun intended). Anyway students these days never ever get to think about mass specs like this. It's just an aluminum box to them where samples go in one end and come out the other. wonderful, thank you for this video which I will now make required for my students. Maybe I can build it myself. A little higher voltage and bigger magnet you could get the mass resolution to resolve that doublet peak, and get a better read on what the small peak is. My guess is double sodium, which would be 46.

[@masonp1314]

That oil diffusion pump looks awesome!! I'd love to see a project like making your own neon sign, using it!

[@ivarsvilums]

I always enjoy and am inspired by your videos. They hearken back to the old "Amateur Scientist" column that I couldn't wait to read each month in my younger days. Projects like "Build an Inexpensive X-Ray Machine" and "A Homemade Atom Smasher" would always open new frontiers of what is possible and, even if the project was beyond my reach at the time, seemed to lead to experiments and projects that I otherwise would not have thought of doing as well as using what I had at hand and seeing things in new ways. Your projects are like that. Thanks! When you mentioned building a gas chromatograph it brought back memories of a project I worked on back around 1979-80. I was working for a medical instrument company in a department charged with developing technology for the 10 - 15 year future time frame and one of the projects I worked on was a micro gas chromatograph. The goal was to create a handheld GC that could continuously analyse blood gasses from samples obtained non-invasively from a patch on the skin. The company ultimately dropped the project (ultimately the entire department was dropped and the company has gone through a number of owners) but we did create a variety of prototype pieces to test our ideas out and, by the end of the project, we were able to analyse 100 microliter samples of 4 gasses in Helium in around 20 milliseconds in continuous operation. Alas, much of our work is long lost but I have been collecting and putting online a "lost technology" archive and have a copy of an internal review document about the project scanned and posted, full of technical details, that you might find interesting and useful. You can find the scanned pages at: www.eastjesus.net/tech/microGC/GCProjectReview-cover.html A colleague from that project went on to spend a career doing research in the mass spec area and I've stayed in touch (he was here for Thanksgiving last week!). I'm sending the link to this video to him and hope that he may find time to contact you. Best wishes!

[@SuperSuperGenius]

I believe the peak you see at 104 V which calculates to 47 amu is Titanium that may be allowed into the filament.

[@bobason456]

I'm sure he would have done a control run without loading the sample? AND/OR Sending the sample to a professional lab would not cost a lot and give you a baseline of what is in this salt substitute.

[@CaptinJangles]

Hmm, what gives me pause about this is the fact that the graphs between his and the other sources match up so well, and that the distortion caused by both potassium ions is present in the second hump. That would mean all 3 filaments would've had to have a similar amount of Titanium and read it the same every time. To me that implies this is more of an error with this method of collection that is endemic to the design.

[@drawapretzel6003]

thats what im suspecting, i suggested to do the math to figure out what element it WOULD be if it were a real element, and find where it is coming from. All the papers seem to have it, and if they are all using tungsten electrodes, surely a nearby element would show up?

[@mckenziekeith7434]

@@CaptinJangles maybe something funny is going on with an impurity in the filament. I am sure the filament is not pure tungsten. What else would be in it? Maybe all three experimenters used tungsten filaments from bulbs, and maybe the manufacturing process of tungsten filaments has been unchanged over all these decades.

[@CaptinJangles]

@@mckenziekeith7434 Yeah, but to me it seems unlikely that the manufacturing process would go unchanged since the 60's. Not to mention who knows if it is even the same across different manufacturers? I mean, I'm sure it's possible. The only way to eliminate this possibility is to run it again with a different substance and see if there's another bump in the same or similar spot. My thinking, but I didn't mention it since I was afraid of looking stupid/not understanding the concept is that there's a reflection of the ion beam that echos back but weaker and at a lower voltage, or that the power alternation is not perfect and some of the ions aren't shifted as far but it leaves a similar distribution.

[@rpearson]

Great video, this is amazing! A couple of things. 1) The peak height is not as important as the peak areas if we are trying to figure out the relative amounts of the isotopes. Since the two peaks are unresolved from each other its moot. 2) I'd secure the turbo molecular pump because if something fails and the turbine is exposed to an immediate pressurization then that thing is going to fly!

[@henryD9363]

I was thinking the same thing about area versus peak. Area indicates the amount of ions. The peak is more of an indication of how good the resolution is.

[@Scrogan]

I’d like to see your take on the standard light spectrometer, as diffraction gratings and CCDs are quite cheap compared to what the MEMS spectrometers seem to go for. Great science being done here!

[@cylosgarage]

this is the first one of your projects that went completely and utterly over my head. well done.

[@DarrenDIY]

Jesus christ, you're the only one on youtube that does this type of advanced physics, i like. Thanks👍😍😀

[@freeelectron8261]

Really great mass spec diy, I have come back to this one many times. AS channel rocks!

[@Neptunium]

another great video! One thing with mass spectrometer is the existence of poly atomic interference, Carbon and Chlorine could add up to look like mass 47 . Potassium is particularly troublesome in ICP-MS due to Argon interference. Or the 2 slits are creating the mirror image, but was it the same design in the previous 1970 experiment? A wider scan could reveal more interference .. great work as always!

[@mohammad-mahditaghipour4307]

I learn something from this person every time..., He is so good at what he does.

[@SubbashPadmanabhan]

Have you done a reference run without sample? Of course you might have. Its truly inspiring that you built a mass spectrometer. I understood lot of things fundamentally from your video. Thanks a lot.

[@sdas7731]

Excellent effort. I want to build one for myself but I am chemist and not an engineer. Again I have a suggestion. If you could put a valve in front of the sample holder, you need not break the vaccume every time you insert a new sample. You can close the valve to the main unit. open another valve to let some air in and feed the sample. Attach the vaccume unit with the second valve and start it. It will take much less time as it has to evacuate a small space. When the desirable pressure is reached open the first valve and continue with the operation.

[@hpekristiansen]

You need the area, not the peak heights -maybe you are already doing that. Calibrate the spectrum axis with several know peaks.

[@blichte1]

Depending upon the shape of the peaks, this isn't strictly necessary; but you are correct -- it is more proper to use the peak integral.

[@Stefun8D]

I've heard the adage that our current calculators could get a ship to the moon, i never thought that a mass spectrometer could be made at home. Thank you for making this content!

[@tihzho]

7:24 !!!!! Don't boil the oil!! I felt a great disturbance in the vacuum, as if millions of diff pumps suddenly cried out in terror and were suddenly silenced. The diff pump oil should just have some slight movement during operation.

[@boboften9952]

IT'S A TRAP.

[@feedmyintellect]

Dude! I love your brain! DIY Electron microscope. Mass spectrometer. 👏👏👏 You only have CT Scan, MRI, and particle accelerator left to build (that is if you have not built those already). I have a ton of respect for you! Most scientists focus and get deep in one particular area. Your focus is multi-disciplinary. That is amazing. Keep up the great work!

[@jasony25]

I like watching every minute of this video.

[@beautifulsmall]

Science is about discovery and understanding, The basic principles are often easy (low energy) to demonstrate but difficult to explain, Ben does an amazing job . I am in awe, kiln cooling , getting daughter to plot the cooling rate to say when I can open it,

[@Muonium1]

*OMG HE READS AND CONSIDERS THE COMMENTS!!* DIY Functional Magnetic Resonance Imager in 2020 plz!!! 🤓🥼🧲📻🧠 upvote if you agree!

[@AppliedScience]

There have been legit MRI (not functional) machines described using Earth's field (kzbin.info/www/bejne/bZK1fHSOeZmXd8k) , as well as permanent magnets (www.opensourceimaging.org/project/instructional-tabletop-mri-scanner/) . I've been really tempted to recreate these, and it's been on my list for a long time. Getting fMRI to work would really be the next level though ;)

[@raptor4916]

Do they have schematics for DIY NMR machines

[@backgroundkiller]

@@AppliedScience Well actually, there is a paper that describes a full build for a Earth-field NMR, that could also be used for some image reconstruction, see: iopscience.iop.org/article/10.1088/0957-0233/21/10/105902/meta I also texted the corresponding author and he was very kind, he also provided me a working link for the arduino code.(www.phas.ubc.ca/~michal/Earthsfield) The project is pretty sophisticated concerning the spool manufacturing, but for someone like you, it would be possible to do and may even improve on the design. Thank you for your awesome, entertaining and informative videos! Keep up your good work

[@bojangles5503]

@@AppliedScience do some cool experiment with a gunn diode

[@tolipwen1487]

Thanks for your contribution to my edutainment! :-) There is also an SA article for making a gas diffusion pump. Decades ago a person could purchase CDs with collections of SA Amateur Scientist articles. I once dabbled in 'pushing glass' for telescope and laser optics and I learned a lot from the SA articles. Not my main source but good additional content. Please keep doing what you do! It's refreshing to see 'uphill both ways, barefooted, in the snow' treated as an invitation instead of an excuse.

[@HerraTohtori]

The second spike looks almost like a second order diffraction maximum. You have a slit (two, in fact) in the device and you're pushing particles through it. There's going to be diffraction pattern of some kind... the question is, would that effect be big enough to be detected in this way? Or is that just shown as "blurry spikes"? Based on my calculations, a 39 amu, 1 elementary charge ion gains a velocity of about 24,969 m/s over an electric field of 126 volts (and it will have energy of 126 electronvolts). At that speed, a particle with mass of 39 amu will have a deBroglie wavelength of approximately 4.1e-13 metres. You mentioned that the width of the slit is about 3-4 thousandths of an inch, which comes to about 0.1 millimetres. Since the disparity between the gap width and the wavelength is so large, I don't think there should actually be a lot of diffraction, but still, the diffraction angle can be calculated. With the above wavelength, the first order diffraction angle would be 2.35e-7 degrees. Estimating the length of travel for the ions as about 0.1 metres from emitter to detector, the actual distance between diffraction spikes should be in the order of 4.1e-10 metres, or about 0.41 nm. That seems like too small a difference, so this is likely not the correct answer. But it would be really cool if it actually was that! It might be worth doing the math on how this diffraction would affect particle path and what voltage would result in the diffracted particles hitting the detector. The assumption of a constant radius of curvature would only apply if the beam is very tight, unless I'm mistaken. If the angle of the particles arriving to the magnetic field varies, then different velocities (that is, different emitter voltage) can cause them to hit the detector. Although simpler explanation is probably contamination, like another commenter said, possibly titanium from the filament used to heat up the sample. Also, are you getting a spike for chlorine? It should be at about 131 volts, by my calculations; that is the voltage that gives chlorine ions the velocity at which they have a matching curvature with potassium ions at 126 volts, so they should be hitting the detector at about that voltage range.

[@maximilianlindner]

That is actually quite clever.

[@JohnVKaravitis]

tl;dr

[@bluesteel255]

The chlorine atoms would be bent in the other direction due to their charge so they do not make it through the tube curve

[@HerraTohtori]

@@bluesteel255 Yes, but you could just switch the positions of the transmitter and the receiver - or change the direction of the magnetic field, if that's feasible. For calibration purposes, the latter would be better. But both should work equally. EDIT: Actually, assuming the chlorine ions are negative, you'd also have to invert the voltage of the emitter so that the point of origin is negative voltage (ground) and the slit is positive voltage. Negative ions would travel in the opposite direction in the electric field. You would also get a negative voltage at the receiver end. But these are fairly minor calibrations.

[@CafeBikeGirl]

For that matter clean the ion source and prepare the sample with distilled water that doesn't have chlorine to see if the spike drops.

[@RedLegion]

To say that I'm envious of your abilities would be a gross understatement. Well done, sir. Please don't stop.

[@MiniLuv-1984]

Excellent video - glad you reposted the whole vid - was so let down when the earlier video stopped mid sentence! Thanks, love your videos and your presentation style. The mirroring theory is a good one I think. To me it looks like a splitting of the beam due to acceleration voltage, via a different path through the magnetic field which, as you pointed out varies across the tube. Would a iron wedge from the end of the magnet to the tube focus the field more?

[@MisterRorschach90]

Never felt more proud in having been subbed. This dude built a mass spectrometer. Seriously.

[@DrDeFord]

FYI, C14 decays by beta emission to N14, not C12.

[@dwightelvey645]

Years ago, I used to work with Dr Emiliani at the University of Miami in South Florida. We had 2 types of mass spectrometers. One was a low resolution that we used mostly as a leak detector. For that it was mostly tuned to helium but we often times looked at other things as well. The other that we had was an isotope ratio mass spectrometer. This requires a longer flight path than you have. This was used for paleo temperature work( looking for ice ages ). We did this by taking a particular foraminifera that live at the ocean surface. We'd sort these out by hand and then use some acid to change them to C02. That would be fees into the mass spectrometer. I mainly worked there because I understood the electronics. Any way, the foraminifera would fractionate the oxygen ratios. I also help in a carbon 14 lab that used a modified scintillation counter( I modified it ).

[@tom_forsyth]

Gotta watch until 24:35 for the best twist ever. It was right there all along! Great stuff.

[@jacobrezek1924]

“nothing is an impossiblity. so we try to do the best we can” my motivational quote for the day

[@johnpublic6582]

Don't discount that the 47 is Titanium as in TiO2 as a whitening agent. It's an "inactive" ingredient so may not be listed on the package.

[@Minifig666]

Perhaps there could be titanium in the filament, or the filament support too?

[@belg4mit]

I'm skeptical of all the proposals regarding titanium because the other papers are decades old, and it seems unlikely that manufacturing processes for the proposed sources will have remained the same all this time... or that they will have been so cavalier with their use of pricier titanium in the past: inflationmonkey.blogspot.com/2012/11/titanium-almost-as-inexpensive-as-it.html

[@JackFou]

@@belg4mit I'm also a bit skeptical of the proposal that the people who made these devices in the past would claim to observe two potassium isotopes without verifying whether the m/z ratio is correct. In the comparison of the spectra at 21:10, his signal looks quite a bit different than the ones from SA or John Dewdney. So maybe the were actually able to resolve the two potassium peaks and we're just looking at differently scaled x-axes?

[@Basement-Science]

@@belg4mit TiO2 costs A LOT less than Ti metal. TiO2 is actually found directly in nature and has been mixed into anything from tooth paste to wall paint for a long time. I think it's pretty likely what he measured.

[@bpj1805]

But would "whitening agent" be 10% or more of the product?

[@cogoid]

Awesome as usual! Another possible project to try: "ion mobility mass spectrometer" -- it does not require any vacuum at all. You see them used at the airports to detect explosives.

[@LightPhoenix7000]

My initial suspicion as to the lower peak is some sort of additive. A mass of 47 corresponds to titanium, and titanium dioxide can be used as a food-grade additive. I think perhaps ordering some pure potassium chloride from one of the chemical companies and testing that would definitively rule out any additives from food-grade sources.

[@jayk8594]

indeed. he starts the video be saying he's going to verify the contents of the product, but then by the end behaves as though his bottle of "No Salt" is a reference standard! :) the picture of it on amazon lists five other ingredients, one of which is mineral oil(!).

[@janami-dharmam]

It is indeed easy; TiO2 is insoluble in water whereas KCl is soluble. Even 1% of TiO2 will produce a milky suspension (and not a transparent clear solution)

[@jeremyarmstrong7857]

This guy is on another freaking level. Diy mass spectrometer, diy electron microscope. Like can literally builds whatever he wants

[@Spirit532]

A spectrometer with lasers... surely it's not laser desorption/ionization? Can't be Raman, you've done Raman before... Regarding vacuum - tube seals generally don't work well with vacuum. Air always leaks through, since there's nothing really holding it back but uneven hose clamp pressure. The reason your stoppers work is because the stoppers themselves are being pressed in by the atmosphere. This is why all vacuum flanges are flanges - to ensure the atmosphere squeezes them together. As for the rubber, most generic rubbers outgas a small enough amount to not be noticeable in this low vacuum system. That, and you have a gigantic turbopump compared to the overall size of your chamber... On that note, have you considered the possibility that something is being vaporized from the chamber(including the stopper) and is ending up on that left peak? It would also fall in line with the previous two works, since they seem to have both used rubber.

[@sbreheny]

Along these lines, what about trying it by cleaning out everything and not intentionally putting anything on the filament and see whether you get any peaks.

[@a3xccy379]

MALDI is the acronym I guess he was referring to it is a type of Ionization technique which uses Lasers to ionize instead of the heated filament. If memory serves me right, it is matrix assisted laser desorption/ionisation.

[@a3xccy379]

@@sbreheny I doubt that would be useful since the copper tube in itself has weathered from the inside and has thus a reactive oxygen layer which might be out gassing either due to vacuum or because of the electric current

[@Xsodouse]

there are titanium blades, so it is possible that this material will be dragged into the process.?

[@Kevin-xi6pj]

@@a3xccy379 atmospheric pressure LDI is likely what he is referring to in the video, fundamentally indifferent to MALDI in terms of the analytical setup (let's ignore laser choice) and is held within the subset of LDI within the acronym soup chemists work within.

[@ts2wv]

These videos remind me of being an intern with some fun project and four months to get some results out of an idea and a paper. Great vid!

[@JimGriffOne]

If you were to use a magnetron to "heat up" the sample, would that prevent the other spike in the frequency response from appearing? (So long as it's operating outside of the frequencies you wish to measure).

[@shanejohns7901]

We made these things in high school chemistry class out of some plastic film and paper-towel tubes. I remember the class quite well, actually. After each group made their spectrometers, the teacher set out 3 'unknown' samples of salts. And we were expected to identify the salts based on our readings. This was back in the mid 80s.

[@Nanotick1]

Did you do a dry run with nothing on the filament to see if anything is emitted from it?

[@zulucharlie5244]

Excellent suggestion.

[@CafeBikeGirl]

Measuring background noise should be a part of any mass spectrometer measurement so hopefully he did, although it seems like he's using the potassium as his known standard so maybe he didn't get that far before releasing a video.

[@monk8235]

Ha! That's awesome. I'm engage with analytical scientists quite a bit, and thought, "I wonder if Applied Science" has made a mass spec. Kudos! You never cease to amaze!!!

[@oghry]

You should characterize more materials in your spectrometer to determine the nature of the second peak

[@CafeBikeGirl]

... aand he could characterize less materials in the spectrometer to help determine the nature of the second peak, hahaha.

[@beautifulsmall]

OMG, I didn't think this channel could get any cooler,(except the liquid nitrogen cryopump one). I tried to make an electron microscope many years ago, so Im just blown away by this, and so far Ive only watched 30 seconds.