Analysis of organochlorines in harbor seal (Phoca vitulina) tissue samples from Alaska using gas chromatography/ion trap mass spectrometry by an isotopic dilution technique

Abstract

A gas chromatography/ion trap mass spectrometry (GC/ITMS) method was developed for the determination of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) in harbor seal (Phoca vitulina) tissues. Tissue samples were homogenized, lyophilized and fortified with (13)C-PCBs 28, 123, 169 and 170, and then extracted with an accelerated solvent extractor with a mixture of hexane and methylene chloride (1:1, v/v). After lipid removal using a 40% H(2)SO(4)-modified silica gel column, all organochlorines were collected in one fraction and further fractionated with an activated carbon/silica gel (1:20) column into a first fraction containing OCPs, non-coplanar PCBs and (13)C-PCBs 28, 123 and 170, and a second containing PCNs, coplanar PCBs and (13)C-PCB 169. Prior to GC/MS/MS analysis, (13)C-PCB 169 was added into the first fraction as an injection standard and (13)C-PCB 170 into the second fraction to calibrate the recoveries of the fortified internal standards. This method can effectively eliminate matrix interferences, and has high selectivity and sensitivity. Recoveries averaged 45-86% for OCPs with relative standard deviations (RSDs) of 2-14%, 52-137% for PCBs with RSDs of 3-29% and 36-152% for PCNs with RSDs of 7-29% from lard and chicken heart samples, which were used as alternative matrices to harbor seal samples in recovery studies. The limits of detection for OCPs, PCBs and PCNs were 0.7-1.9, 1.5-8.9 and 0.5-10 pg/g dry weight, respectively. This method can be used to analyze OCPs, PCBs and PCNs in harbor seal blubber, liver and kidney samples.

Synthesis of some deuterated dialkylaminoethyls as possible standards for the mass spectrometric monitoring of chemical warfare agents

“…Firstly, the benefits of direct integration into the analytical procedure are appreciated and quite typically the use of labelled compounds in the methods based on mass spectrometrylabelled compounds serve as perfect internal standards 3 (i.e. confirmation of recovery of sample preparation, 4 correction of suppression/enhancement during the ionization process, 5 quantification using the isotopic dilution method 6 and so on). Secondly, labelled compounds facilitate the study on the CWA transformation processes and allow their products to be traced in the environment.…”

Analytical methods applied to the determination of pesticide residues in foods of animal origin. A review of the past two decades

“…However, some authors [1,3,8,[11][12][13]15,26,27,29,31,37,41,43,54,71] utilised sodium sulphate from the grinding step during the extraction procedure to further disintegrate the sample. Sodium sulphate was also used at the early partitioning step of the analytical procedure for pesticide extraction from milk [10,73].…”

“…Indeed, SFE techniques have not tended to be widely used for pesticide analysis in food from animal origin. Recently, accelerated solvent extraction (ASE) using a pressurised liquid extraction system (Dionex ® ), was applied to organochlorine pesticide extraction from animal internal organs, muscles, adipose tissue, eggs and milk [37,39,54,83] as well as from fish liver and flesh [13,84] and shellfish [85]. The main advantages of ASE are low solvent consumption and the short time needed for performing the extraction step, but the purchase cost of the equipment is higher than that of the standard Soxhlet method [13].…”

“…Alternatively, MS/MS, by decreasing such matrix influence, may achieve a higher selectivity level and lower detection limit [18,36]. GC-MS/MS has been used for analysing pesticide residues on fatty food with either triple quadrupole [36][37][38] or ion trap mass spectrometers [54,99]. Both the multiple reaction monitoring (MRM) [36] and the selected reaction monitoring (SRM) [37] acquisition methods have been applied to the GC-MS/MS analysis of pesticide residues in foods of animal origin.…”

“…In aquaculture farms, fish feed, contaminated by pesticides, is a potential source of direct introduction into fish [53]. Consequently, fish are a major source of contamination for both top marine predators [54] and human consumers [48].…”