Identification of toxaphene congeners in bird eggs by combining quadrupole NICI-mS and ion trap EI-MS/MS

Abstract

Quadrupole negative ion chemical ionisation (NICI) mass spectrometry (MS) and ion trap electron ionisation (EI) tandem mass spectrometry (MS/MS) were applied to the identification of toxaphene congeners in eggs from different species of Norwegian predatory birds. Identification criteria were retention time, degree of chlorination (NICI), and the abundance ratio between two daughter ions (m/z 269 and m/z 233) selected from the full scan daughter ion spectrum after collision induced dissociation of m/z 305 (EI-MS/MS). In this way the following congeners could be unequivocally detected: Parlar #26, #32, #38, #40, #41, #42, #44, #50, #51, #58, and #63 as well as the recently described toxaphenes B7-1453 and B8-1412. Furthermore, a number of hitherto unreported toxaphenes were found. Compared to NICI-MS, ion trap EI-MS/MS suppressed interferences from sample matrix and other polychlorinated compounds more efficiently. The advantages of the proposed approach were demonstrated by analysing the congener pattern present in seven eggs from Norwegian birds of prey. Levels of toxaphenes (80–740 ng/g wet weight) were two to twenty times lower than for chlordanes (170–1 600 ng/g wet weight) and polychlorinated biphenyls (2900–8000 ng/g wet weight). Parlar #26, B8-1412, #40, #41, #50 contributed about 80–90% to the quantified toxaphene burden.