SIMULTANEOUS DETERMINATION OF SUB-MG/1 LEVELS OF SULFUR AND CHLORINE IN LIQUID HYDROCARBONS BY A COUPLED COMBUSTION-ION CHROMATOGRAPHY TECHNIQUE

A method for elemental analysis that employs a novel coupled combustion-ion chromatography (C-IC) apparatus is described in detail. The samples are combusted and the products collected in a dilute peroxide solution. This solution is loaded onto a concentrator column which is then introduced into the injection position of a suppressed conductivity anion chromatography system. The method is rapid, reliable, free from interferences and has the capacity for simultaneous determination of sulphur and chlorine in organic liquids at concentrations down to 0.03 mg/l. Provided that the capacity of the concentrator column is not exceeded, the recovery for organic standards of both chlorine and sulphur in a variety of organic solvents is greater than 93%, irrespective of the solvent and the sample volume and concentration. Repeatability is only slightly worse than that observed for conventional direct IC analysis of aqueous solutions. At concentrations of 0.4 mg/l Cl and 0.5 mg/l S, the % standard deviations (n = 10) were found to be 2.9 and 3.5% respectively. The results obtained with the C-IC analyser for both standards and petroleum-based samples are in good agreement with those obtained by microcoulometry.