Journal Published Online: 01 July 2000
Volume 45, Issue 4

Formation of an Interfering Substance, 3,4-Dimethyl-5-Phenyl-1,3-Oxazolidine, During a Pseudoephedrine Urinalysis

CODEN: JFSCAS

Abstract

During fatal aviation accident investigations, biosamples from the victims are submitted to the FAA Civil Aeromedical Institute (CAMI) for drug analysis. In the process of one such analysis by CAMI, an unknown substance was found in a urine sample. Simultaneous screening by thin layer chromatography (TLC) and gas chromatography/FID (GC/FID) suggested the presence of pseudoephedrine. A subsequent routine confirmation analysis of a separate urine aliquot by GC Fourier transform infrared (GC/FTIR) and GC mass spectrometry (GC/MS) indicated that the retention times of the unknown substance matched with those of pseudoephedrine. However, its infrared and mass spectra were different—the -OH and-NH groups were missing, a C-O-C group was present, and the molar mass was 12 atomic mass units (amu) more than that of pseudoephedrine. A subsequent literature search suggested that ephedrine-like amines react with aldehydes to form oxazolidines. Therefore, the 12-amu increase could be accounted for by condensation of pseudoephedrine with formaldehyde. Since this aldehyde is present in various grades of methanol and ethyl acetate, and these solvents were used during the solid-phase extraction, 3,4-dimethyl-5-phenyl-1,3-oxazolidine was synthesized by using (+)-pseudoephedrine·HCl and formaldehyde. The analytical findings of the synthesized compound were consistent with those of the unknown interfering substance, confirming that it was the oxazolidine. Aldehyde contaminants in solvents or specimens can transform drugs of interest and may result in misidentification of a compound originally present in specimens. Therefore, chemicals used in analyses should be of the highest available purity, and a multi-analytical approach should be adopted to maintain a high degree of quality assurance.

Author Information

Lewis, RJ
Civil Aeromedical Institute, Federal Aviation Administration, Toxicology and Accident Research Laboratory, AAM-610, Oklahoma City, OK
Huffine, EF
Armed Forces Institute of Pathology, Rockville, MD
Chaturvedi, AK
Civil Aeromedical Institute, Federal Aviation Administration, Toxicology and Accident Research Laboratory, AAM-610, Oklahoma City, OK
Canfield, DV
Civil Aeromedical Institute, Federal Aviation Administration, Toxicology and Accident Research Laboratory, AAM-610, Oklahoma City, OK
Mattson, J
University of Southern Mississippi, Hattiesburg, MS
Pages: 4
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Stock #: JFS14794J
ISSN: 0022-1198
DOI: 10.1520/JFS14794J