Packed-capillary supercritical fluid chromatography of pesticides using phosphorus-selective detection

Abstract

SummaryPacked-capillary, supercritical fluid chromatography using carbon dioxide modified with methanol or 2-propanol as mobile phase, was coupled with a thermionic detector for Phosphorus-selective detection. Optimum conditions for thermionic detection were established for a number of hydrogen flow rates by adjusting the air flow rate and bead Position. Using the mentioned modifiers, a series of organOphosphorus pesticides of varying polarity could be separated within 8 min. An optimum sensitivity of 55-128 fg P/ s and linearity over four ordcrs of magnitude were obtained. The detector showed good selectivity for phosphorus Over carbon and nitrogen, viz., 9 9 104 g C/g P and 75 g N/ g P, respectively. This was demonstrated by determining pesticides such as phoxim, dimethoatc and azinphos-methyl In onion and tomato extracts.

Applications of Supercritical Fluids in Industrial Analysis

“…Recently, however, Mol et al (1991) showed that by adjusting the hydrogen flow, the air flow and the bead position, very promising results were obtained in phosphorus-selective determination of pesticides. With packed capillary columns and modifiers added to carbon dioxide, the minimum detectable quantity was 15-65 pg of pesticides.…”