Determination of low molecular weight aliphatic primary amines in urine as their benzenesulphonyl derivatives by gas chromatography with flame photometric detection.

A selective and sensitive method for the determination of low molecular weight aliphatic primary amines in urine is described. These amines were converted into their benzenesulphonyl derivatives by a modified Hinsberg procedure, and measured by gas chromatography with flame photometric detection (FPD-GC) using a DB-1 capillary column. The derivatives were very stable and provided excellent FPD responses. By FPD-GC, linear calibration curves were obtained in the range 10-200 ng of methylamine, ethylamine, n-propylamine, isobutylamine and n-butylamine using tert-butylamine as an internal standard, and the detection limits of these amines were ca. 6-25 pg as the injection amount. Benzenesulphonamide derived from ammonia was converted into its N-dimethylaminomethylene derivative which has a longer retention time, and separated from benzenesulphonyl derivatives of low molecular weight primary amines on the chromatogram. The recoveries of aliphatic primary amines added to urine samples were 91-107% and the relative standard deviations were 0.2-4.5%. Analytical results of aliphatic primary amine contents in urine samples of normal subjects are presented.