/sci/ - Science & Math » Thread #12445012

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Anonymous Thu 10 Dec 01:18:58 2020 No.12445012 View Reply Original Report

Quoted By: >>12447200 >>12447332 >>12447394 >>12447585

Has anyone here worked with quadrupole mass spec?
I understand why arsenic is tricky, but how the hell do you diagnose bad arsenic spikes when you've recalibrated and cleaned the machine, changed out stock solutions, check the lab water, and remade internal standards?

Anonymous

Anonymous Thu 10 Dec 2020 10:29:53 No.12447200 Report

Quoted By:

>>12445012
now try again, and this time state exactly what your problem and observations were, plust post the output spectra.

Anonymous

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Anonymous Thu 10 Dec 2020 11:11:56 No.12447332 Report

Quoted By: >>12447394

>>12445012
lol I agree with that pic

Anonymous

Anonymous Thu 10 Dec 2020 11:31:05 No.12447394 Report

Quoted By: >>12447544 >>12447547

>>12445012
>>12447332
doctor here, what's wrong with nmr?

Anonymous

Anonymous Thu 10 Dec 2020 12:16:50 No.12447544 Report

Quoted By:

>>12447394
MS and IR cheaper and more versatile
MS analyze do absolutely anything from metals in solution to organics in vapors, depending on technique and design
IR is almost as versatile, but can be coupled to microscope and in real time tell you what is the spec you are looking at made of and it can fit inside your pocket
NMR needs to be cryogenically cooled, sample needs to be in deuterium solvent, can only determine structure and it can fit inside a large room

the only thing NMR is useful for is finding out structure of new compounds and for that you are often better off with tandem MS-MS
it was cool in the 60's, but now it's pretty much obsolete

Anonymous

Anonymous Thu 10 Dec 2020 12:20:14 No.12447547 Report

Quoted By: >>12447997 >>12448989

>>12447394
MS and IR are cheaper and more versatile
MS can analyze absolutely anything from metals in solution to organics in vapors, depending on technique and design
IR is almost as versatile, but can be coupled to a microscope and in real time tell you what is the spec you are looking at made of and it can fit inside your pocket
NMR needs to be cryogenically cooled, sample needs to be in deuterium solvent, can only determine structure and it can fit inside a large room

the only thing NMR is useful for is finding out structure of new compounds and for that you are often better off with tandem MS-MS
it was cool in the 60's, but now it's pretty much obsolete

Anonymous

Anonymous Thu 10 Dec 2020 12:29:02 No.12447585 Report

Quoted By:

>>12445012
I work with quadrupole mass spec...although exclusively for UHV systems. I know for us we have to be careful about the cracking pattern (e.g. carbon monoxide can also show carbon and oxygen peaks) for the various compounds that are present. Maybe this is causing what appears to be arsenic?

Anonymous

Anonymous Thu 10 Dec 2020 15:13:18 No.12447997 Report

Quoted By: >>12448025

>>12447547
>NMR almost obsolete
lmao cope more, tube jockey

Anonymous

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Anonymous Thu 10 Dec 2020 15:24:17 No.12448025 Report

Quoted By:

>>12447997

Anonymous

Anonymous Thu 10 Dec 2020 19:08:20 No.12448989 Report

Quoted By:

>>12447547
This has to be bait. NMR is far and away a more powerful technique for characterisation of organic/organometallic compounds. Mass-spec is basically just for screening, and IR basically doesn't tell you shit if your molecule isn't extremely simple in its structure or doesn't have any carbonyls or similar moieties.

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