SELECTIVE DETERMINATION OF SECONDARY-AMINES AS THEIR N-DIETHYLTHIOPHOSPHORYL DERIVATIVES BY GAS-CHROMATOGRAPHY WITH FLAME PHOTOMETRIC DETECTION

A selective and sensitive method has been developed for the determinat ion of secondary amines by gas chromatography (GC). After removal of p rimary amines by the reaction with o-phthaldialdehyde, secondary amine s were converted into their N-diethylthiophosphoryl derivatives and th en measured by GC with flame photometric detection using a DB-1701 cap illary column. The derivatives were sufficiently volatile and stable t o give single symmetrical peaks. The detection limits of secondary ami nes were ca. 0.05-0.2 pmol per injection. N-Methylcyclohexylamine was used as an internal standard. The calibration curves for secondary ami nes in the range 1-20 nmol were linear and sufficiently reproducible f or quantitative determination. This method was successfully applied to small urine samples without prior clean-up. Overall recoveries of sec ondary amines added to urine samples were 91-105%. By using this metho d, secondary amines in urine samples could be analysed without any inf luence from primary amines and other coexisting substances. The analyt ical results of secondary amine content in urine samples of normal sub jects are presented.