Sulfur-Selective Detector for Liquid Chromatography Based on Sulfur Monoxide-Ozone Chemiluminescence

We report here a new detector for HPLC, employing gas-phase chemiluminescence for selective detection of liquid-phase sulfur compounds. This detector operates by converting sulfur-containing compounds in the liquid phase, under pressure and at elevated temperatures, into sulfur monoxide. The SO is allowed to permeate across a membrane, into a helium stream, and is swept into a reaction cell. Ozone is added to the cell, and photoemission resulting from the SO + O-3 reaction is monitored by a photomultiplier tube. The method reported here has been shown to operate effectively at 0.4-9.9 mL/min flow rates, typical of analytical HPLC, ion chromatography, and flow injection analysis. The design and performance of the new liquid-phase sulfur analyzer is described. The parameters most affecting the detector response are the reaction capillary temperature and pressure, the composition of the Liquid mobile phase, and the oxidation state of sulfur in the parent analyte. Application of the detector to reversed-phase HPLC analysis of standards of sulfur-containing pesticides, proteins, and blood thiols and FIA of acid-soluble thiols in rat plasma is presented.