engleski

Analysis of polychlorinated biphenyls in human milk collected in Zagreb, Croatia

Analytical determination of PCBs in human milk includes three phases: extraction of fat and compounds from milk samples, clean up and qualitative and quantitative determination. Milk fat and investigated compounds are extracted from milk samples by organic solvents (n-hexane, chloroform, etc.) or solvent mixtures (diethyl- ether/ethanol, acetone/ n-hexane, etc.). Clean up of extracts could be done with sulphuric acid, but also with solid phase extraction and gel permeability chromatography. Gas chromatography with electron capture detector is used for qualitative and quantitative determination of PCBs. The method previously used for determination of organochlorine pesticides and total PCBs was developed for the analysis of twenty PCB congeners in human milk. The analysed compounds were: PCB-28, PCB-52, PCB-60, PCB-74, PCB-77, PCB-101, PCB-105, PCB-114, PCB-118, PCB-123, PCB-126, PCB-138, PCB-153, PCB-156, PCB-157, PCB-167, PCB-169, PCB-170, PCB-180 and PCB-189. The PCB congeners were extracted from milk with a mixture of chloroform and methanol (1:1). The extracts were cleaned up with sulphuric acid. PCB congeners were determined by gas chromatography with electron capture detection (^63Ni). Two columns of 60 m length with stationary phase SPB-5 and one of 30 m length with stationary phase SPB-1701 were used. The best recoveries were obtained for PCB-153 (109%), PCB-138 (102%), PCB-180 (93%) and PCB-77 (85%). The recoveries for PCB-74, PCB-105, PCB-114, PCB-118, PCB-123, PCB-126, PCB-156, PCB-157, PCB-167, PCB-169, PCB-170, and PCB-189 ranged from 60% to 80%, and for PCB-28, PCB-52, PCB-60, and PCB-101 from 56% to 58%. The method was applied for the analysis of 28 human milk samples collected in Zagreb in 1998./99. Milk samples were collected from mothers living in Zagreb who were not occupationally exposed to investigated compounds. Mother’s age were in range 19 – 44 years and they were nursing their first to eight child. Samples were collected 1.5 – 38 weeks after delivery. All samples contained PCB-74, PCB-138, PCB-153, and PCB-180. The concentrations of PCB-28, PCB-52, PCB-101, PCB-138, PCB-153, and PCB-180 were in the range of 0 - 346 microgram/kg milk fat. The most toxic congeners PCB-77, PCB-126, and PCB-169 were in the range of 0 - 35 microgram/kg milk fat, while the concentration range of other PCBs was 0 - 82 microgram/kg milk fat. Levels of PCB congeners determined in samples collected in Zagreb are within the range determined in the other European countries. Levels of dioxin-like PCB congeners in human milk collected in Zagreb are within the lower level of European range.

Polychlorinated biphenyls; human milk; gas chromatography

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