Optimization and validation of a gas chromatographic method for analysis of (RS,SR)-diastereoisomeric impurity in formoterol fumarate

The levels of 2-amino-9H-pyrido2,3-b]indole (AalphaC or 2-amino-alpha-carboline), 2-amino-3-methyl-9H-pyrido2,3-b]indole (MeAalphaC or 2-amino-3-methyl-alpha-carboline), 9H-pyrido3,4-b]indole (norharman), and 1-methyl-pyrido3,4-b]indole (harman) have been determined in the mainstream smoke condensate from three reference cigarettes, namely Kentucky reference 1R5F, Kentucky reference 2R4F, and CORESTA CM4. The amino-alpha-carbolines, and norharman and harman (beta-carbolines) can be classified as heterocyclic aromatic amines (HAAs) and are listed as biologically active agents in the mainstream smoke of cigarettes. For the analysis, the mainstream smoke condensate from cigarettes was collected on a filter pad, the analytes were isolated using solid-phase extraction (SPE), and quantified without derivatization on a GC-MS. Total amounts of carbolines found in the condensate increased from ultralight 1R5F to full-flavor CM4 cigarettes. The level of harman was about 250 ng/cigarette for the 1R5F cigarette and about 1025 ng/cigarette for the CM4 cigarette. Norharman was typically three times more abundant than harman. The AalphaC was found at about 10 times lower level compared to harman, and MeAalphaC was about 50 times lower than harman. The use of reference cigarettes can provide a common measure for laboratories to assess carboline amounts among cigarette brands.