Increasing the accuracy of determination of nC/nH ratios by gas chromatography–atomic emission detection

The influence of oxygen content in helium on the accuracy of nC/nH ratio determination for model mixtures of aliphatic and polyaromatic hydrocarbons and polychlorinated biphenyls was studied. The best accuracy was achieved at the oxygen content ca. 9%, which was the maximal possible oxygen content in helium for this GC–atomic emission detection (helium flow rate was 25 ml min−1). Using the maximal oxygen flow in plasma the nC/nH ratio determination accuracy improvement was accompanied by 10-fold increase in detection limit.