Specific detection in gas—liquid chromatographic effluents with on-line high-performance liquid chromatographic optical detector

Abstract

High-performance liquid chromatographic (HPLC) optical detector technology has been adapted for use with gas—liquid chromatography (GLC). Compounds in the effluent of packed GLC columns were scrubbed continuously, with minimal loss of resolution, into a liquid stream flowing at a nominal rate of 1 ml/min. This was done through the use of a capillary tube that simulated an open-tubular GLC column in which the liquid phase was continuously replaced. The liquid stream was then debubbled and drawn through the flow cell of the appropriate HPLC detector. Mixing the liquid effluent with o-phthalaldehyde reagent led to the formation of derivatives of primary amines and ammonia that were detected with high sensitivity and specificity by their fluorescence. Scrubbing the effluent into methanol followed by on-line monitoring of fluorescence or UV absorbance permitted UV absorbing and fluorescent compounds such as aromatic and heterocyclic compounds to be measured in gasoling with minimal interference from other compounds. The results demonstrated the feasibility of using the high specificity and sensitivity of HPLC detector technology with GLC. This should prove useful in trace analyses in which GLC is the preferred separation technique, but there are interfering quantities of compounds with similar chromatographic properties in the mixture.