Our current GC/MS protocol can not distinguish between metamizole and 4-methylaminoantipyrine. 4-Methylaminoantipyrine is a metabolite of metamizole. Their mass spectra are indistinguishable because metamizole undergoes thermal decomposition to 4-methylaminoantipyrine and aminopyrine during GC-MS analysis. The chemical identified in this sample could be either Metamizole or 4-Methylaminoantipyrine, or a combination of the two.
Jul 7, 2021: Identification of Metamizole changed to Metamizole OR 4-Methylaminoantipyrine.
Dec 11 2019: We're ordering the standard for 4-methylaminoantipyrine so we can be more certain about the identification.
Dec 9, 2019: Now with the metamizole standard in-hand at the lab, the spectrum and compound originally identified in this sample as 4-methylaminoantipyrine has been revised to metamizole.4-methylaminoantipyrine is a metabolite of metamizole and has a very similar mass spectrum. Although it is theoretically possible the chemical in this sample could be the compound 4-methylaminoantipyrine, it's less likely to be that since it's the metabolite and our main analytical toxicologist believes the new identification is correct.
Dec 4, 2019: A reference standard is available for metamizole, and has been ordered for the lab to test it and see how it behaves in their GC, and whether it shows up like this sample did.
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Our current GC/MS protocol can not distinguish between metamizole and 4-methylaminoantipyrine. 4-Methylaminoantipyrine is a metabolite of metamizole. Their mass spectra are indistinguishable because metamizole undergoes thermal decomposition to 4-methylaminoantipyrine and aminopyrine during GC-MS analysis. The chemical identified in this sample could be either Metamizole or 4-Methylaminoantipyrine, or a combination of the two.
Dec 11 2019: We're ordering the standard for 4-methylaminoantipyrine so we can be more certain about the identification.
Dec 9, 2019: Now with the metamizole standard in-hand at the lab, the spectrum and compound originally identified in this sample as 4-methylaminoantipyrine has been revised to metamizole.4-methylaminoantipyrine is a metabolite of metamizole and has a very similar mass spectrum. Although it is theoretically possible the chemical in this sample could be the compound 4-methylaminoantipyrine, it's less likely to be that since it's the metabolite and our main analytical toxicologist believes the new identification is correct.
Dec 4, 2019: A reference standard is available for metamizole, and has been ordered for the lab to test it and see how it behaves in their GC, and whether it shows up like this sample did.