Airborne concentrations of toxaphene congeners at Point Petre (Ontario) using gas-chromatography-electron capture negative ion mass spectrometry (GC-ECNIMS)

A reliable analytical method has been developed using GC-ECNIMS for the det ermination of individual toxaphene congeners in ambient air. To allow a rea sonable comparison with previous data for toxaphene reported by Muir and co -workers using GC-ECD, this method has adopted their approach of focussing upon the identification and quantification of specific peaks or clusters (" T" species) typically observed in environmental samples, with the sum of th ese "T" species then being reported as "total toxaphene". Technical toxaphe ne has been used as the analytical standard, but independent response facto rs have been assigned to the target peaks and clusters. Because of the appr eciable variability in ECNIMS response shown by individual toxaphene congen ers, this is considered to be a reasonable and potentially more accurate pr ocedure than the application of a "single response factor" used by many oth er workers. The methodology has been used for the determination of toxaphene in air sam ples collected over the annual cycle in 1992 and then from October 1995 to September 1997 at Point Petre, Ontario. Of the forty-four calibrated compon ents, only 10 were detected in all of the air samples collected over the la tter 2-year period. Airborne concentrations of toxaphene (defined as the su m of the calibrated components) range from 0.9 pg/m(3) to 10.1 pg/m(3). A c lear seasonality has been observed, with a summer-to-winter concentration r atio of about 6. (C) 1999 Elsevier Science Ltd. All rights reserved.