HIGH-PRECISION SAMPLING OF TRACE GAS-BORNE VOLATILES BY THE DYNAMIC SOLVENT EFFECT WITH A COMPARATIVE REVIEW OF ALTERNATIVE TECHNIQUES

The precise determination of traces of organic volatiles is particularly challenging in semiochemistry and clinical chemistry, where specimen sizes are intrinsically limited and amounts of trace components correspondingly very small. This demands a sampling technique that is fully compatible with the ability of capillary columns and gas chromatographic detectors to separate and quantify nanogram and sub-nanogram amounts from complex mixtures. The quantitative precision of dynamic solvent-effect sampling of low parts per billion (109) aqueous carbonyl compounds, high ppb and low parts per million aqueous phenols, low ppb and high parts per trillion (1012) airborne hydrocarbons and the volatiles from wine, human urine and a slow-release pesticide was tested with specimen sizes that yielded amounts of volatiles down to the sub-nanogram level. Provided that sources of variability, such as temperature changes, adsorption on containers, incomplete peak resolution and changes in the specimens themselves, were adequately controlled, dynamic solvent-effect sampling consistently provided coefficients of variation in peak areas, peak percentage areas and peak-area ratios of less than 10% at nanogram and sub-nanogram levels. The literature was surveyed for data on the performance of other sampling systems. None of them have been demonstrated to match the precision of the dynamic solvent effect with such small amounts from such a wide range of materials. © 1990.