Analytical methods - PCBs

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EN 1528-1:1996 Fatty food – Determination of pesticides and polychlorinated biphenyls (PCBs) – Part 1: General

EN 1528-2:1996 Fatty food – Determination of pesticides and polychlorinated biphenyls (PCBs) – Part 2: Extraction of fat, pesticides and PCBs, and determination of fat content

EN 1528-3:1996 Fatty food – Determination of pesticides and polychlorinated biphenyls (PCBs) – Part 3: Clean-up methods

EN 1528-4:1996 Fatty food – Determination of pesticides and polychlorinated biphenyls (PCBs) – Part 4: Determination, confirmatory tests, miscellaneous

 

Other methods available

 

ISO 8260:2008 – Milk and milk products – Determination of organochlorine pesticides and polychlorobiphenyls – Method using capillary gas-liquid chromatography with electron-capture detection

 

US EPA Method 1668B: Chlorinated biphenyl congeners in water, soil, sediment, biosolids and tissue by HRGC/HRMS – determination of dioxin-like and non-dioxin like PCBs in fish tissue.

 

 

Alternative methods from literature

 

-          Baeyens et al. PCBs and PCDD/Fs in fish and fish products and their impact on the human body burden in Belgium. Arch. Environ. Contam. Toxicol. 2007, 52, 563-571.

Method for the chemical analysis of the non-dioxin like PCBs (28, 52, 101, 118, 138, 153, 180) is based on the normalized CEN method EN 1528-1:1996.

The following key steps can be identified:

 

-          Homogenization of the food sample;

-          Extraction of fat with a mixture of hexane/acetone (1:1) in presence of 25 g anhydrous Na2SO4. An ASE extraction was performed;

-          Removal of acetone with aqueous Na2SO4 solution (2 %)

-          Addition of 13C-internal standards, i.e. isotopically labelled non-dioxin like PCBs

-          Purification of fat (0.4 g) on silica acid column (6 g of silica/H2SO4 60/40, 1 g of Al2O3, 10 % water and 0.5 g of anhydrous Na2SO4).

-          Elution of the PCBs of interest with hexane

-          Measurement of the non-dioxin like PCB congeners on an Ion Trap in MS/MS mode.

-          Quantification of the PCBs based on 13C-PCB/12C-PCB ratios (isotopic dilution) using a 5-point linear calibration.

 

-          Pirard, C., Focant, J.-F., De Pauw, E. An improved clean-up strategy for simultaneous analysis of polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), and polychlorinated biphenyls (PCB) in fatty food samples. Anal. Bioanal. Chem. 2002, 372, 373-381.

 

The dioxin-like mono-ortho PCBs are analysed together with the non-dioxin like PCBs.

The following key steps can be identified in the analytical method:

 

-          Sample preparation for high-fat content food samples

  • Homogenization of the samples
  • Freezing of the samples under liquid nitrogen
  • Freeze-drying of the samples
  • Fat extraction by means of Pressurized Liquid Extraction (PLE)
    • Hexane as solvent
  • Drying of fat extracts over Na2SO4
  • Determination of the lipid content by gravimetric analysis

-          Clean-up of the fat extract

  • Use of an open chromatographic multi-layer glass column freshly packed with:
    • 6 g of acid silica
    • 1 g of deactivated alumina
    • 0.5 g Na2SO4
  • Dilution of the fat extract (0.5 g) with 2 mL hexane
  • Elution of the column with 20 mL of hexane
  • Evaporation of the solution containing PCBs
  • Addition of dodecane as keeper

-          Analysis by GC-MS/MS