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Author Topic: GC-MS/MS system: Methanol to formaldehyd problems  (Read 2479 times)

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GC-MS/MS system: Methanol to formaldehyd problems
« on: February 16, 2011, 09:55:11 AM »

Hello fellow analytical chemmists.
I faced with a problem that started recently and suddenly on out GC-MS/MS system.
We are screening for a range of drugs, but suddenly methamphetamine started acting very wierd.
We usually get one big peak, but now we get 2 small peaks with diffrent masses and a "smear" between them.
We dissolve all our samples in methanol, and we found that methanol is converted to formaldehyd (via the Mannich reaction ) in the presence of metal and heat/pressure. The formaldehyd reacts with methamphetamine and gives a diffrent product, hence the two small peaks, one methamphetamine and the other methamphetamine+formaldehyd (could someone explain the reacion between methamphetamine and formaldehyd + maybe give me the mass of the product?).
We suspekt that the metal that catalyses the reaction with methanol comes from the inlet/liner.
It is not an option to dissolve samples in other then methanol.
And it is not an option to lower the liner/inlet temp (220C).
The collum temp is 50C and rises to 70C.

Does anyone have any idea what we could do?
Could we add something that would prevent the formation of formaldehyd but not ruin the rest of the analysis?
Also can u recommend any other forums that i could possible use?
Best regards

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