How to capture, transport and test a gas?
May 7, 2013 3:20 PM Subscribe
I want to test what the composition of a gas is, and I don't even know where to begin. I don't have access to a lab, but I know enough people that might have access to equipment to help, if I knew what to ask for. And I also need some ideas of how to capture and transport the gas.
I raise seahorses. One condition that afflicts seahorses is the accumulation of gas in their bodies, subcutaneous, internally or within their pouch. Unlike other fish with gas bubble disease, this happens in cases where there isn't gas supersaturation in the water. It can happen in that circumstance, but public aquariums have tested for supersaturation when this happens, and most cases haven't found instances of supersaturation.
There are a few hypotheses about why it happens, but it's never been tested really. One of the prevailing ones would suggest that the gas buildup has to be CO2. So I want to test this.
I have a male right now with the pouch manifestation, meaning his pouch fills with gas. I can remove it it fairly easily, which is what got me thinking I could probably capture the gas and test it. But I'm not sure how best to capture the gas, and then what to do to prevent it from being contaminated, and what equipment I would need to test.
So far for capturing the gas, I was thinking of using an iv catheter (the sleeve, not the needle) to release the air under water. I do this now. But I was then thinking of having a cup held under water over where I am releasing the bubbles to trap the gas; and then using a syringe to extract the gas from the cup. I have a crude drawing of what I am describing.
If this isn't a good way to capture the gas, any other thoughts? And how do I transport it, since I likely will need to test it someplace else.
Finally, how do I test it? I remember chemistry years ago we did various things to discover the composition of a gas, but I can't recall what they were. Also, there will likely be less than .5ml of gas to test. If possible I'd like to test at home, but I can reach out to various friends and acquantainces that might have access to lab equipment if I know what to ask for.
I raise seahorses. One condition that afflicts seahorses is the accumulation of gas in their bodies, subcutaneous, internally or within their pouch. Unlike other fish with gas bubble disease, this happens in cases where there isn't gas supersaturation in the water. It can happen in that circumstance, but public aquariums have tested for supersaturation when this happens, and most cases haven't found instances of supersaturation.
There are a few hypotheses about why it happens, but it's never been tested really. One of the prevailing ones would suggest that the gas buildup has to be CO2. So I want to test this.
I have a male right now with the pouch manifestation, meaning his pouch fills with gas. I can remove it it fairly easily, which is what got me thinking I could probably capture the gas and test it. But I'm not sure how best to capture the gas, and then what to do to prevent it from being contaminated, and what equipment I would need to test.
So far for capturing the gas, I was thinking of using an iv catheter (the sleeve, not the needle) to release the air under water. I do this now. But I was then thinking of having a cup held under water over where I am releasing the bubbles to trap the gas; and then using a syringe to extract the gas from the cup. I have a crude drawing of what I am describing.
If this isn't a good way to capture the gas, any other thoughts? And how do I transport it, since I likely will need to test it someplace else.
Finally, how do I test it? I remember chemistry years ago we did various things to discover the composition of a gas, but I can't recall what they were. Also, there will likely be less than .5ml of gas to test. If possible I'd like to test at home, but I can reach out to various friends and acquantainces that might have access to lab equipment if I know what to ask for.
Disclaimer: I do remember a bit of high school & university chemistry, and that's all I'm working off of.
Rather than a cup, use a test tube with a cork. Uncork it and allow it to flood with water. You will need to release the gas into it directly, not just under it. Not sure of your setup. Regardless, the gas will displace the water in the tube, which you can then just cork up while still underwater and remove. Then it'll just be the water and gas. Ask a friend with a gas spectrometer about the appropriate method, cleanliness, etc. The water will probably outgas a bit. No idea if that is a problem.
If you have a syringe, approach it from the bottom, up. That way the needle doesn't puncture the cup and release the gas.
posted by jwells at 3:36 PM on May 7, 2013
Rather than a cup, use a test tube with a cork. Uncork it and allow it to flood with water. You will need to release the gas into it directly, not just under it. Not sure of your setup. Regardless, the gas will displace the water in the tube, which you can then just cork up while still underwater and remove. Then it'll just be the water and gas. Ask a friend with a gas spectrometer about the appropriate method, cleanliness, etc. The water will probably outgas a bit. No idea if that is a problem.
If you have a syringe, approach it from the bottom, up. That way the needle doesn't puncture the cup and release the gas.
posted by jwells at 3:36 PM on May 7, 2013
Gas sampling is pretty specialised. As you have determined, the sample collection, storage and transport is pretty hard. There are gas sampling bags, but they are probably bigger that you need (I remember them being about a litre). A GC could do it, but a GC/MS would be overkill unless it turns out to be some crazy complicated organic gas. If you can find a lab that does gas sampling, they can probably tell you what they need. However, if it's only one sample, and it isn't a routine analysis for them, the price will probably be way more than you want to pay. (I think we charged about $300 per sample, though they were more complicated)
If it's just CO2 you're interested in, you can do a test with CaO. I think. Wait, will google. It's Ca(OH)2, which turns cloudy with CO2. Have a google around and see if you can find a method that you can duplicate. If you can get hold of some Ca(OH)2, that would probably be the easiest way. (You can test your method with dry ice, if you can find a source of that, or even a soda stream).
I've also use gas detection tubes by Kitigawa. I'm not sure what their tech support is like, but it may be worth giving them an email. It's a fairly simple system, though I can't remember how expensive they are. Have you talked to any aqarium shops? I would have thought they would have a way of testing for CO2, even if it's just in water, that you might be able to adapt.
posted by kjs4 at 4:12 PM on May 7, 2013
If it's just CO2 you're interested in, you can do a test with CaO. I think. Wait, will google. It's Ca(OH)2, which turns cloudy with CO2. Have a google around and see if you can find a method that you can duplicate. If you can get hold of some Ca(OH)2, that would probably be the easiest way. (You can test your method with dry ice, if you can find a source of that, or even a soda stream).
I've also use gas detection tubes by Kitigawa. I'm not sure what their tech support is like, but it may be worth giving them an email. It's a fairly simple system, though I can't remember how expensive they are. Have you talked to any aqarium shops? I would have thought they would have a way of testing for CO2, even if it's just in water, that you might be able to adapt.
posted by kjs4 at 4:12 PM on May 7, 2013
Wow, what an interesting problem. I'd love to throw out a few ideas here; hopefully people more knowledgable than me will come along soon.
I agree that it would be awesome if you could get the gas sample into a GC/MS. But in the meantime, there are a couple of things you might be able to do if you suspect that's it's CO2 gas.
First, perhaps you could do some indirect sleuthing using a pH meter. CO2 gas dissolves into water. Some of the dissolved gas forms carbonic acid, and some of the carbonic acid dissociates to form H+ ions along with bicarbonate. Those H+ ions make the water more acidic. SO, I'm thinking that you could take a baseline measurement of the tank water's pH. Then stick your cup into the tank and collect the gas. (This is where my idea gets fuzzy-- I don't know, how easy will it be to get the co2 to dissolve into the water? Do you need to shake it up or heat it?) Anyhoo, then you measure the pH of the cup of tank water + seahorse gas, and if the acidity has increased (pH has dropped), then you could suspect that the gas is C02.
Second, you could buy a sensor that measures the amount of CO2 gas.
Third, and I have no idea if this could be helpful to you, I'm just throwing out brainstorm ideas, could you somehow capture the gas more easily using a common device used for brewing beer, an airlock? They allow air bubbles to escape water without letting new air back in. I think you can jimmy them to capture the released air. But for seahorse size, you'd probably need a tiny airlock and might have to make it yourself.
That's all I've got. I'll be watching this thread closely to see if anyone has better ideas!
posted by sunnichka at 4:17 PM on May 7, 2013
I agree that it would be awesome if you could get the gas sample into a GC/MS. But in the meantime, there are a couple of things you might be able to do if you suspect that's it's CO2 gas.
First, perhaps you could do some indirect sleuthing using a pH meter. CO2 gas dissolves into water. Some of the dissolved gas forms carbonic acid, and some of the carbonic acid dissociates to form H+ ions along with bicarbonate. Those H+ ions make the water more acidic. SO, I'm thinking that you could take a baseline measurement of the tank water's pH. Then stick your cup into the tank and collect the gas. (This is where my idea gets fuzzy-- I don't know, how easy will it be to get the co2 to dissolve into the water? Do you need to shake it up or heat it?) Anyhoo, then you measure the pH of the cup of tank water + seahorse gas, and if the acidity has increased (pH has dropped), then you could suspect that the gas is C02.
Second, you could buy a sensor that measures the amount of CO2 gas.
Third, and I have no idea if this could be helpful to you, I'm just throwing out brainstorm ideas, could you somehow capture the gas more easily using a common device used for brewing beer, an airlock? They allow air bubbles to escape water without letting new air back in. I think you can jimmy them to capture the released air. But for seahorse size, you'd probably need a tiny airlock and might have to make it yourself.
That's all I've got. I'll be watching this thread closely to see if anyone has better ideas!
posted by sunnichka at 4:17 PM on May 7, 2013
Response by poster: Thanks for the great suggestions everyone! I like the idea of the at home co2 test. I want to be able to test for other components as well though. For instance, one mostly discarded idea is that it's actually trapped air from bubbles in the water. I'm pretty sure that it is not going to be that, but I'd like to at least say for this one seahorse tested, it is not. Or, if it does turn out to be atmospheric gas, then that turns the current theory of it being CO2 on its head.
I think someone I know as an acquaintance has a Gas chromatography–mass spectrometry though I swear he said it was a gas spectrometer - I don't know if that's a different device, or if I'm misremembering, or if it's a different name for the same thing. But I don't know him well so I don't want to come off sounding like an idiot. But from what I'm reading here, that would be the ideal tool for this?
I'm also going to give the co2/ph drop a try. The problem is that it's such a small amount of gas, I have no idea what kind of drop to expect. Still if I use a test tube with very little volume, maybe that will work. I only have chemical test kits for ph, but I might be able to borrow a calibrated probe from someone to get a more accurate measurement. Still, I don't know how much a tiny amount of co2 would effect a relatively large body of water. Say I trap .5ml with 5ml of water, is that enough to make a change?
posted by [insert clever name here] at 5:17 PM on May 7, 2013
I think someone I know as an acquaintance has a Gas chromatography–mass spectrometry though I swear he said it was a gas spectrometer - I don't know if that's a different device, or if I'm misremembering, or if it's a different name for the same thing. But I don't know him well so I don't want to come off sounding like an idiot. But from what I'm reading here, that would be the ideal tool for this?
I'm also going to give the co2/ph drop a try. The problem is that it's such a small amount of gas, I have no idea what kind of drop to expect. Still if I use a test tube with very little volume, maybe that will work. I only have chemical test kits for ph, but I might be able to borrow a calibrated probe from someone to get a more accurate measurement. Still, I don't know how much a tiny amount of co2 would effect a relatively large body of water. Say I trap .5ml with 5ml of water, is that enough to make a change?
posted by [insert clever name here] at 5:17 PM on May 7, 2013
Response by poster: I should add, it's possible it's not atmospheric air - o2 and n2 have been suggested as possibilities as well. And for all I know, it could be something entirely outside that sphere.
posted by [insert clever name here] at 5:19 PM on May 7, 2013
posted by [insert clever name here] at 5:19 PM on May 7, 2013
Response by poster: Argh, I mean atmospheric air and co2 aren't the only possibilities. Left out co2 in my last comment and didn't notice until the edit timeframe had passed.
posted by [insert clever name here] at 5:41 PM on May 7, 2013
posted by [insert clever name here] at 5:41 PM on May 7, 2013
I think the best way to harvest the gas is with a syringe. Stick in the needle and suck it out.
posted by Chocolate Pickle at 6:44 PM on May 7, 2013
posted by Chocolate Pickle at 6:44 PM on May 7, 2013
You are going about this backwards - find the people who will do the analysis first, and ask them how to trap and transport the gas. They may have some specific vial they want the gas to be in, and they definitely have done something like his before.
posted by Dr Dracator at 9:18 PM on May 7, 2013
posted by Dr Dracator at 9:18 PM on May 7, 2013
Response by poster: Dr. Dracator, your probably right... I was just hoping to have some idea of what is involved so I could figure out who to ask about what. I really don't know where to begin with this quest, other than I casually known people working with access to various lab equipment and I think I could get them to help, if I knew what to ask.
posted by [insert clever name here] at 9:55 PM on May 7, 2013
posted by [insert clever name here] at 9:55 PM on May 7, 2013
Response by poster: Kjs4, I just realize what Ca(OH)2 is, and I have plenty of that (it's great for raise calcium and alkalinity in aquariums). A company not too far from here sells dry ice, last time I bought it, it was about $8/lb. That was a few years ago, but I should be able to get it and run some practice tests.... So I can at least test for co2 at home if I can't find more advanced equipment.
posted by [insert clever name here] at 10:56 PM on May 7, 2013
posted by [insert clever name here] at 10:56 PM on May 7, 2013
What I think you need is someone with access to a laser absorption spectrometer. Not sure how large of a sample they're going to want, though.
posted by Kid Charlemagne at 11:50 PM on May 7, 2013
posted by Kid Charlemagne at 11:50 PM on May 7, 2013
I have nothing to offer, but I do applaud your innovation, and your determination to assess something by testing it. The ticket with this, as in all similar situations I have encountered is persistence. You may have to do it several times, each time increasing the sophistication of capture or measurement, but if you don't give up, soon you'll have an answer. Excellent.
posted by FauxScot at 1:00 AM on May 8, 2013 [1 favorite]
posted by FauxScot at 1:00 AM on May 8, 2013 [1 favorite]
I wouldn't worry about finding someone with a GC or a GC/MS. he GC/MS is certainly overkill because the MS is going to only sample above a molecular weight of 100 or so. There is just too much random stuff floating about in even "pure" gas to start detecting below that, and most interesting things are above that limit anyways. I think the major issue you will have in identifying this is going to be that the gas is so simple it is difficult to identify. A GC-MS pushes a carrier gas (usually N2 or Argon) down a capillary and slowly ramps up the temperature. The more volatile things come off first and seeing as your stuff is a gas it would come out nearly immediately. Assuming this is a pure gas you are looking to pick out ions of a gas from the background and if the gas is pure CO2 you are looking for something like 1% max of a background of N2. That is quite a difficult thing to do, and if your gas is air you're looking at a significantly different problem because you're losing 75% of your sample because it is exactly the same as the carrier gas.
In reality I think the best way to go would be to use a different technique, and as a first pass I would recommend IR. That way you could take a blank of a vacuum and then add in your gas sample and compare the peaks that are present. CO2 has a fairly unique stretch so that should be seen if it is pure CO2, but also you can analyse the mixture using IR so if it is actually just atmospheric air (ie 75% N2 20%O2 etc.) yuou will be able to tell because you can take a blank that consists of air very easily instead of a vacuum and it would look similar.
As far as the mechanics of taking a gas sample the easiest is to get a syringe with a good stopcock fitted to it and some narrow diameter tubing. Capture the gas using liquid displacement as you see fit from the suggestions above and calculate the void volume of the tubing. Uptake the void volume and expel it to "clean" the system and then uptake the remainder of the gas. Close the stopcock and make sure it doesn't come off in transit. I do think this would be best done by talking with someone who has the actual bits of kit though as finding a gas phase IR might be difficult, but it should give you the best information.
posted by koolkat at 3:58 AM on May 8, 2013 [3 favorites]
In reality I think the best way to go would be to use a different technique, and as a first pass I would recommend IR. That way you could take a blank of a vacuum and then add in your gas sample and compare the peaks that are present. CO2 has a fairly unique stretch so that should be seen if it is pure CO2, but also you can analyse the mixture using IR so if it is actually just atmospheric air (ie 75% N2 20%O2 etc.) yuou will be able to tell because you can take a blank that consists of air very easily instead of a vacuum and it would look similar.
As far as the mechanics of taking a gas sample the easiest is to get a syringe with a good stopcock fitted to it and some narrow diameter tubing. Capture the gas using liquid displacement as you see fit from the suggestions above and calculate the void volume of the tubing. Uptake the void volume and expel it to "clean" the system and then uptake the remainder of the gas. Close the stopcock and make sure it doesn't come off in transit. I do think this would be best done by talking with someone who has the actual bits of kit though as finding a gas phase IR might be difficult, but it should give you the best information.
posted by koolkat at 3:58 AM on May 8, 2013 [3 favorites]
Response by poster: koolkat, would something like this do the job if I can't find anyone that has the equipment?
posted by [insert clever name here] at 4:15 AM on May 8, 2013
posted by [insert clever name here] at 4:15 AM on May 8, 2013
That experiment is exactly what I think you should do.
posted by koolkat at 4:36 AM on May 8, 2013 [1 favorite]
posted by koolkat at 4:36 AM on May 8, 2013 [1 favorite]
Sounds like you're more interested in the answer (what is this gas?) versus learning how to determine the answer. You might consider contacting a chem professor at the nearest university.
posted by at at 9:43 AM on May 8, 2013
posted by at at 9:43 AM on May 8, 2013
Response by poster: Yes, this is true; while it wouldn't hurt to learn how, I'm much more interested in the answer. Funds are an issue so I can't just pay for someone to do it. But contacting the local university isn't a bad idea. It's one of those issues I'm *amazed* has not been studied (most researchers are interested in studying them in the wild). It's a problem that has plagued seahorses in captivity for years, include those in public aquariums and research settings. It's more common in home aquariums, but it still crops up in public aquariums. Many vets have their own personal theory to the cause, so even though there is a prevailing theory, I want to try and start to unravel the mystery.
But I'd also like to find a method that's reproducible. One seahorse isn't enough to say that is the only gas found. One hypothesis suggests that its a symptom that pops up under a variety of causes, and that could include producing different gases. Ideally I'd like to try it on my ill seahorse, and then figure out a way to either collect the gas from other seahorses and have them shipped to me OR have a way that I can explain to other seahorse keepers to test the gas.
I realize testing the gas is just a start. It's thought to be environmentally induced, but the bugger of it all is if you have a tank of 5 seahorses, one might come down with the disease, the others might be fine. Or all 5 might get it. Moving to a different aquarium frequently causes it to go into remission, but not always. I've found books dating back to 1960 discussing the issue; and yet I've not been able to find any papers published on the condition. The best we've got is a statement and theory (hypothesis) from a vet at the Shedd Aquarium, and medication that works sometimes that has lead to that hypothesis.
I'm not a scientist,but I play one on TV but I hope to treat this as rigidly as I possibly can. Which means I've got some learning to do. I've had some basic science courses in college but that was close to 20 years ago. I read research papers all the time and understand them for the most part, but also this thread has my head swimming. That's good though, I need to challenge the old noggin every once in a while.
Re the Ca(OH)2 test, I'm going to start with that, namely because I need to remove some of that gas within the next day or two, and I can do that more at home with equipment I have on hand. Any idea the amount of Ca(OH)2 in solution compared to the volume of gas? Videos on youtube show people using their breath to complete it, and it seems like a comparatively large volume of gas to the water. However, they're just blowing into it with a straw, so some is obviously escaping. I was thinking I'd put the gas in a testube with the calcium hydroxide solution and shake it up to get the two to mix.
posted by [insert clever name here] at 11:57 AM on May 8, 2013
But I'd also like to find a method that's reproducible. One seahorse isn't enough to say that is the only gas found. One hypothesis suggests that its a symptom that pops up under a variety of causes, and that could include producing different gases. Ideally I'd like to try it on my ill seahorse, and then figure out a way to either collect the gas from other seahorses and have them shipped to me OR have a way that I can explain to other seahorse keepers to test the gas.
I realize testing the gas is just a start. It's thought to be environmentally induced, but the bugger of it all is if you have a tank of 5 seahorses, one might come down with the disease, the others might be fine. Or all 5 might get it. Moving to a different aquarium frequently causes it to go into remission, but not always. I've found books dating back to 1960 discussing the issue; and yet I've not been able to find any papers published on the condition. The best we've got is a statement and theory (hypothesis) from a vet at the Shedd Aquarium, and medication that works sometimes that has lead to that hypothesis.
I'm not a scientist,
Re the Ca(OH)2 test, I'm going to start with that, namely because I need to remove some of that gas within the next day or two, and I can do that more at home with equipment I have on hand. Any idea the amount of Ca(OH)2 in solution compared to the volume of gas? Videos on youtube show people using their breath to complete it, and it seems like a comparatively large volume of gas to the water. However, they're just blowing into it with a straw, so some is obviously escaping. I was thinking I'd put the gas in a testube with the calcium hydroxide solution and shake it up to get the two to mix.
posted by [insert clever name here] at 11:57 AM on May 8, 2013
Response by poster: koolkat, if you're still reading this, can you point me to information on how to perform the test? Those instructions I linked are just for building the chamber, and I can't seem to find the supplemental instructions on how to use it that they make reference to in the paper. Do you have any links on how to do the test? I tried looking for IR gas phasing but the only thing I could find was about specific experiments that had used it, but not how to do it myself. My google fu is probably failing me because I'm outside my depth.
posted by [insert clever name here] at 9:11 PM on May 8, 2013
posted by [insert clever name here] at 9:11 PM on May 8, 2013
You would only need to build that chamber if the place that had the FTIR machine didn't already have a gaseous chamber. What is the volume of gas that you could reasonably expect to get? Either way you're going to have to find someone with an IR machine (a fairly cheap bit of kit but expensive if you're not used to lab prices you could probably pick one up for $20k but a university near you will have a couple in their chem department and probably wouldn't mind you using it.) If you PM me your location (City and State or country is fine) I can try and look through nearby universities and give you some leads, Hell if you're near Leeds UK and are willing to build the chamber we can head over and run it whenever you want)
The most problematic issue for you would be the analysis of the results. You'll get an IR chromatogram and will need to know how to interpret it to determine the identity (and also the concentration with some calibrations with pure samples) of the gas. CO2 has a stretch in the 2200-2400 ish cm-1 (its been a long time since I've had to do IR) I'm not sure what N2 or O2 are but methane will be around 2900 cm-1 for the CH stretch along with some others down lower for out of plane bending. All of these peaks are going to be dominated by the water (around 3400 cm-1) but it should be possible to dry the gas also before putting it into the chamber.
What you want to do definitely isn't trivial, but given enough samples and a large enough quantity of gas it should be possible to learn something about the makeup of the gas. As far as the Ca(OH)2 test I probably wouldn't bother. It is a qualitative test that relies on precipitation. If you have a good UV/Vis then maybe because you could monitor the precip more accurately, but essentially you're looking at putting a small amount of gas into a tube and seeing if something gets cloudy. The reason people are blowing into the solution for a while is because it takes your eye a while to notice the difference. I don't think that there would be enough CO2 to cause a noticeable change. Especially if it isn't pure CO2 and is more like 0.1%.
posted by koolkat at 1:42 AM on May 9, 2013
The most problematic issue for you would be the analysis of the results. You'll get an IR chromatogram and will need to know how to interpret it to determine the identity (and also the concentration with some calibrations with pure samples) of the gas. CO2 has a stretch in the 2200-2400 ish cm-1 (its been a long time since I've had to do IR) I'm not sure what N2 or O2 are but methane will be around 2900 cm-1 for the CH stretch along with some others down lower for out of plane bending. All of these peaks are going to be dominated by the water (around 3400 cm-1) but it should be possible to dry the gas also before putting it into the chamber.
What you want to do definitely isn't trivial, but given enough samples and a large enough quantity of gas it should be possible to learn something about the makeup of the gas. As far as the Ca(OH)2 test I probably wouldn't bother. It is a qualitative test that relies on precipitation. If you have a good UV/Vis then maybe because you could monitor the precip more accurately, but essentially you're looking at putting a small amount of gas into a tube and seeing if something gets cloudy. The reason people are blowing into the solution for a while is because it takes your eye a while to notice the difference. I don't think that there would be enough CO2 to cause a noticeable change. Especially if it isn't pure CO2 and is more like 0.1%.
posted by koolkat at 1:42 AM on May 9, 2013
Response by poster: Very small, about 0.5ml. So it sounds a bit like that wouldn't be enough gas if I'm reading your post right? Also probably not something I could build at home, besides the pvc chamber I linked? I know I should probably contact a university, but I'm keen on trying to do this myself if possible.
I thought I'd start with the calcium hydroxide test just because I have the equipment at home and he needs the gas release soon. I can always wait for more to build up in a few weeks.
I've been asking around, and it sounds like someone from our local Makerspace has one of these: http://www.kickstarter.com/projects/jywarren/public-lab-diy-spectrometry-kit
posted by [insert clever name here] at 9:11 AM on May 9, 2013
I thought I'd start with the calcium hydroxide test just because I have the equipment at home and he needs the gas release soon. I can always wait for more to build up in a few weeks.
I've been asking around, and it sounds like someone from our local Makerspace has one of these: http://www.kickstarter.com/projects/jywarren/public-lab-diy-spectrometry-kit
posted by [insert clever name here] at 9:11 AM on May 9, 2013
With quantities that small I honestly wouldn't bother with the Calcium hydroxide test. Even with an unsensitive fly by the seat of your pants spectrophotometer (which is neat but essentially a toy I've built one using a pizza box before and all you would eb able to do is determin the spectral lines if there are any (hint there aren't going to be any unless you arc some electricity through your sample)) It doesn't have the quantation necessary to see the difference by adding in 0.00002 moles of CO2 into the system, and I doubt that a sensitive professional one would really be able to tell the difference either. The main problem with gasses is that there just isn't much of them there at all so they are really difficult to identify. If you were able to bring 0.5 mL of a liquid I could come up with a plethora of ways of determining the compounds in the liquid. Hell with only 0.1 mL I could probably run 100 different tests. With a gas you essentially got nothing there so there isn't much you can do.
Your best bet is to save some up somehow and find someone with a gasphase IR chamber that can do small sample sizes. It wouldn't surprise me if there was one that had a 0.25 mL chamber that would give you decent results off of a single sample.
What you are trying to do isn't easy and there are ways of working around in getting things to work that have been proven, but they're going to be expensive and are going to require something that you can't do in your house. In reality I can almost guarantee you that the sample will have some CO2 present and I don't think it is going to be a pure mixture at all.
posted by koolkat at 9:55 AM on May 9, 2013
Your best bet is to save some up somehow and find someone with a gasphase IR chamber that can do small sample sizes. It wouldn't surprise me if there was one that had a 0.25 mL chamber that would give you decent results off of a single sample.
What you are trying to do isn't easy and there are ways of working around in getting things to work that have been proven, but they're going to be expensive and are going to require something that you can't do in your house. In reality I can almost guarantee you that the sample will have some CO2 present and I don't think it is going to be a pure mixture at all.
posted by koolkat at 9:55 AM on May 9, 2013
Response by poster: Thanks for the info. So it definitely sounds like it's not a do it at home kind of thing. I'll start asking around and see if I can find anyone that has the right equipment.
Is there a reason you don't think it will be a pure gas? They prevailing hypothesis suggests it's a disturbance of the carbonic anhydrase reaction creating
CO2, so I'm expecting to find that. I'm more or less expecting to confirm that it is Co2 but feel that step is necessary before designing further experiments. But I'm also genuinely curious if it will turn out to be co2 and not something else or a mixture of gases.
posted by [insert clever name here] at 12:28 PM on May 9, 2013
Is there a reason you don't think it will be a pure gas? They prevailing hypothesis suggests it's a disturbance of the carbonic anhydrase reaction creating
CO2, so I'm expecting to find that. I'm more or less expecting to confirm that it is Co2 but feel that step is necessary before designing further experiments. But I'm also genuinely curious if it will turn out to be co2 and not something else or a mixture of gases.
posted by [insert clever name here] at 12:28 PM on May 9, 2013
There is no reason that It wouldn't be pure CO2 other than pure things are very rare in nature, especially something as easily miscible as a gas. I also tend to think of the worst case scenario so I have to do less experiments. If you do the perfect experiment correctly you should hopefully be able to identify all of the components of the gas and possibly even have a guess as to their ratios. If it is pure bingo you're done and also if it isn't pure if you do the right one you're still all set. Otherwise you'll run one experiment and see that there is CO2 present but have no idea of the purity, so you have to run another and maybe see that there is some O2 present as well, run another and find a trace of argon and another to fine nitrogen down and down the rabbit hole you go until you find out that it is just air with an elevated CO2 concentration. If instead you ran just the last experiment you would get the same answer but having only run something once. With something as precious as a 0.5 mL sample of gas from a living animal you should run the best possible experiment first and then usnig that knowledge determine if it really was the best experiment and if there is anything else you need to know and run those also, but always run the most useful experiment first.
posted by koolkat at 1:39 AM on May 10, 2013 [1 favorite]
posted by koolkat at 1:39 AM on May 10, 2013 [1 favorite]
Response by poster: Ah. Thanks koolkat. That explanation is very helpful.
posted by [insert clever name here] at 1:51 PM on May 17, 2013
posted by [insert clever name here] at 1:51 PM on May 17, 2013
« Older Please help me increase my knowledge of genomics... | Is it worth it to buy a PS3 in 2013? Newer »
This thread is closed to new comments.
As for catching the gas-- If you can get it into a syringe with as few steps as possible, I wouldn't hesitate to send the syringe to the analytical service.
posted by u2604ab at 3:29 PM on May 7, 2013