GAS-CHROMATOGRAPHIC PROFILING ANALYSIS OF URINARY ORGANIC-ACIDS FROM NONSMOKERS AND SMOKERS

A rapid profiling and screening procedure is described for the compara tive analysis of urinary organic acids among the groups of nonsmokers and smokers. The procedure involves solid-phase extraction of organic acids using Chromosorb P in normal-phase partition mode, with subseque nt single-step conversion to tert.-butyldimethylsilyl derivatives, fol lowed by direct gas chromatographic (GC) analysis on dual-capillary co lumns. A total of forty-two organic acids were positively identified b y retention index (I) matching in urine samples (0.25 ml) from eleven nonsmokers and fifteen smokers studied. When the GC profiles were simp lified to their corresponding organic acid I spectra in bar graphical form, characteristic patterns were obtained for each individual as wel l as for each average of nonsmoking and smoking groups. When stepwise discriminant analysis was performed on GC data after omitting hippuric acid, seven acids were selected as the variables most discriminating between smokers and nonsmokers. The star symbol plots drawn based on t hese discriminants were characteristic of each individual and group av erage, enabling to distinguish smokers from nonsmokers. And canonical plot produced by canonical discriminant analysis using the same variab les as the data vectors displayed two separate clusters representing e ach group. (C) 1997 Elsevier Science B.V.