March 13, 2013
Kevin Clark, Morse Laboratories
Over the last decade, analytical method requirements for agrochemicals in a range of environmental matrices have become increasingly-more demanding in terms of ruggedness, breadth of applicability, and sensitivity, with methods for pyrethroid insecticides being a notable example of this trend. The Pyrethroid Working Group (PWG) has developed methodology that monitors for eight different pyrethroids at low (ca. 0.5 – 5.0 ng/L) concentrations in difficult aquatic based matrices. The current approach utilizes negative chemical ionization gas chromatography with mass selective detection (NCI-GC-MSD), which provides embedded confirmatory information via the capability of the GC to provide separation of characteristic pyrethroid stereoisomers (and thus a fingerprint) and by the monitoring of confirmatory ions. The presentation will highlight the benefits of employing stable isotope internal standards in conjunction with a multi-analyte method for analysis of surface waters, sediments, and other matrices of interest, such as wastewater treatment influent/effluent water and biosolids. It will also discuss other key learnings on practical constraints that make quantifying this class of chemistry a challenge.