CHROMATOGRAPHIC BEHAVIOR OF UNDERIVATIZED LIDOCAINE AND METABOLITES IN CGC

The chromatographic behavior in underivatized form of lidocaine and si x of its metabolites was investigated using capillary gas chromatograp hy (CGC). Ten fused silica capillary columns from different manufactur ers covering a wide range of polarity were tested. On most of the used columns separation of the analytes was obtained; however, the perform ance with respect to peak symmetry varied extensively. An improvement in peak symmetry and resolution was observed using HP1 and Rtx-1 colum ns compared to HT5, despite the fact that all column types were nonpol ar. The highly polar column (BPX70) could separate only five of seven compounds. Generally, the intermediate polar columns (DB17, HP50, and BPX35) showed the best performance with respect to peak symmetry, and at optimal conditions it took only 10 min to separate all the metaboli tes. The effect of different injector temperatures (200-350 degrees C) on the stability of the compounds studied was also investigated. The minimum detectable quantities for lidocaine and its metabolites were b etween 30 and 400 fmol using nitrogen phosphorus detection. (C) 1998 J ohn Wiley & Sons, Inc.