GAS-CHROMATOGRAPHIC SCREENING FOR NEOSTIGMINE AND PHYSOSTIGMINE USINGTEMPERATURE-PROGRAMMED RETENTION INDEXES

Temperature-programmed gas chromatographic retention indices, relative to n-alkane (C standard) and n-alkylbis(trifluoromethyl)phosphine sul phide (M standard) homologous series, were determined for two low-vola tile, highly toxic carbamates. neostigmine and physostigmine on SE-54 fused-silica capillary columns. The influence of temperature programme and sample concentration on the absolute values of the indices were e valuated. Reproducibility of the indices was good in both linear and m ultistep temperature programmes, but the reproducibility and peak shap es were better in the multistep temperature programme. When the compou nds were present in high concentration, C standards and a flame ioniza tion detector were used successfully, but multidetector M standards, w hich also can be seen with the selective alkali thermoionization detec tor, were superior when concentrations were low. Similarly M standards which can be seen also with other selective detectors (electron-captu re, flame photometric and photoionization) could be a suitable index s tandard series for screening of different types of compounds containin g heteroatoms.