Miniaturised sample preparation of fatty foodstuffs for the determination of polychlorinated biphenyls

Abstract

A miniaturised analytical method allowing the exhaustive extraction of environmentally relevant polychlorinated biphenyls (PCBs) from fatty foodstuffs and the purification of the extracts in a single step has been developed. After dispersion of the freeze dried sample on silica modified with 44% (w/w) of sulphuric acid, the mixture was packed in a glass column on top of a multilayer silica column used for removal of the lipids and biogenic co-extracted material. Using this arrangement, a complete sample preparation can be accomplished by two successive 10 min static extractions with hexane followed by a brief dynamic step to ensure purging of the sample and sorbents. The analytical method showed a satisfactory performance, with recoveries of the endogenous PCBs studied in the 81-134% range of those found using a more conventional off-line procedure, even though as small an amount of sample as 0.1 g was used. Detection limits by gas chromatography with micro-electron capture detection (GC-ECD) were in all cases lower than 0.3 ng/g sample (freeze dried basis) and the repeatability of the complete analytical procedure better than 14% (except for PCB 167). When combined with GC and ion trap detection in the tandem mass spectrometry mode, the miniaturised method has been proved to be a valuable alternative to the more expensive high resolution mass spectrometry for fast screening of PCBs 77, 126, and 169, even if these congeners were not isolated from the bulk of PCBs.

Feasibility of gas chromatography – ion trap tandem mass spectrometry for the determination of polychlorinated biphenyls in food

“…Accomplishing the new challenges deriving from these new legal actions requires to adapt the traditional analytical methods used for PCB determination while still fulfilling the quality criteria demanded for these analyses. Thereby, during the last years significant efforts have been made to both increase the sample throughput of the sample preparation protocols in use [2,6,7] and test the feasibility of different GC detectors as alternative to the most sophisticated and expensive HRMS [8][9][10]. Tandem spec-trometric methods have been proved to be a valuable alternative to HRMS for the analysis of non-ortho [9] and the (more abundant) indicator PCBs [8,10].…”

Novel pressurized solvent extraction vessels for the analysis of polychlorinated biphenyl congeners in avian whole blood

“…Surrogate standard 13 C 12 -PCB32 was used for PCB77, 13 C 12 -PCB101 was used for the pentachlorinated PCBs, 13 C 12 -PCB153 was used for the hexaand heptachlorinated PCB compounds and 13 C 12 -PCB194 was used to correct for the non-13 C-labeled PCB194. This procedure produced results that compared favourably with a study looking at the extraction of PCBs in 0.1 g samples of fatty foodstuffs [44]. More importantly, recoveries were in the range of those achieved for serum samples using SPE or other methods that use significantly larger sample sizes [30][31][32]35,42,44].…”

“…This procedure produced results that compared favourably with a study looking at the extraction of PCBs in 0.1 g samples of fatty foodstuffs [44]. More importantly, recoveries were in the range of those achieved for serum samples using SPE or other methods that use significantly larger sample sizes [30][31][32]35,42,44]. Thus, whilst SPE provides an acceptable extraction method for serum, the methodology used in the present work is equally applicable to whole blood, and if necessary, could be adapted to tissue analysis.…”

Modern Methods of Sample Preparation for GC Analysis

“…There are, on the other hand, also several papers which feature miniaturized MSPD of, typically, some 25-100 mg of sample [131,136,137]. To quote an example, Ramos et al [136] analysed PCBs in freeze-dried meat, where only 0.1 g meat was dispersed with 0.1 g of acid silica. The recoveries were 80-130% and the LODs for ECD detection were below 0.3 ng g -1 .…”