Partial conversion of methanol to formaldehyde in the gas chromatography injection port and reactivity with amines.
The partial conversion of methanol (MeOH) to formaldehyde (HCHO) in the gas chromatograph (GC) injection port was studied. The presence of formaldehyde in the injection port can result in reaction with injected analytes, especially primary and secondary amines. A systematic study of this problem was undertaken using norephedrine and ephedrine as probe analytes, and experiments involving varying inlet temperature, comparisons among solvents and solvent mixtures, isotopic labeling, and formaldehyde spiking. These experiments showed a direct correlation between inlet temperature and formation of the amine-formaldehyde condensation products. The mass spectra of the norephedrine and ephedrine condensation products were consistent with addition of the methylene group derived from formaldehyde across the amine and alcohol moieties to form the corresponding oxazolidine-ring compounds. Results for the imine condensation product of didesmethylsibutramine formed in the injection port are also presented.
Pharmaceutical Laboratory, Applied Sciences Group, Health Sciences Authority, 11 Outram Road, Singapore 169078, Singapore. Kee_Chee_Leong@hsa.gov.sg
Chee Leong
CL
Kee
Chian Sing
CS
Lai
Xiaowei
X
Ge
Min Yong
MY
Low
Laura A
LA
Ciolino
D000588:Amines / Q000737:chemistry*; D003503:Cyclobutanes / Q000737:chemistry; D004809:Ephedrine / Q000737:chemistry; D005557:Formaldehyde / Q000032:analysis / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D007097:Imines / Q000737:chemistry; D000432:Methanol / Q000032:analysis / Q000737:chemistry*; D010080:Oxazoles / Q000737:chemistry; D010665:Phenylpropanolamine / Q000737:chemistry; D012997:Solvents / Q000032:analysis / Q000737:chemistry; D013696:Temperature
D000588:Amines; D003503:Cyclobutanes; D007097:Imines; D010080:Oxazoles; D012997:Solvents; C064210:oxazolidine; D005557:Formaldehyde; D010665:Phenylpropanolamine; D004809:Ephedrine; C058254:sibutramine; D000432:Methanol