Methods of the Determination of Selected PCB congeners in Food
B. Szafran, J. Lulek, K. Szyrwińska, A. Pachcińska, E. Nowak, K. Jaraczewska
Department of Inorganic and Analytical Chemistry
Karol Marcinkowski University of Medical Sciences
6 Grunwaldzka St., 60 – 780 Poznań, Poland
A combination of stability and propensity to form gas under appropriate environmental
conditions means that polychlorinated biphenyls (PCBs) are subject to long-range
atmospheric transportation. A combination of their resistance to metabolism and lipophilicity
means that they will accumulate in food chains (1).
In order to accurately determine whether or not the modest PCB exposure experienced
with the declining global load involves a real health risk, it is necessary to examine the
exposure more accurately and in more detail.
Due to the toxicity of certain PCB congeners the determination of their concentrations in
alimentary chain is of major concern.
Taking into the consideration the PCB levels, recently detected in Polish environment (soil,
air, water, sediments) (2,3) and the fact that water presents 3.4% and air 0.04% (4) of the total
daily intake of 23 PCBs congeners, it can be supposed that food chain could be a primary
pathway of human exposure to PCBs in Poland.
Over almost 40 years of continuous determination of polychlorinated biphenyls (PCBs)
in environmental and food samples, the analytical procedures have been changed according to
the world trends in the analysis of trace substances. The validity of a specific analytical
method used for PCBs monitoring should be demonstrated in laboratory experiment.
The aim of our presentation is to show two analytical procedures of the determination of
15 PCB congeners in food products (milk, fish).
The methods of the determination of specific PCB congeners (IUPAC Nos: 28, 52, 74,
101, 105, 114, 118, 128, 138, 149, 153, 156, 170, 180 and 187) selected on the basis of their
toxicity and levels found in environmental, in food matrices were optimized and validated in
our laboratory (5,6).
Determination of analytes in cow or human milk includes: acetone:hexane extraction,
clean-up of extracts by sulfuric acid concentrated and solid phase extraction (SPE) on Florisil.
Extraction of PCB from vegetable oil and fish tissues is preceded by KOH/EtOH
saponification,
The identification and quantification of analytes in purified extracts are carried out by high
resolution gas chromatography (HRGC) on low polarity column (60 m, 0.25 mm, 0.25 m)
with electron capture detection (ECD) and/or low resolution mass spectrometry (LRMS).
The detection and quantification limits of examined analytes depend of the sample amount
( 20 g of milk and 2 g of oil or wet fish tissue) and congener type ( detection limit for PCB No
170 – 0,02 ng/g of milk and 0,14 ng/g oil and detection limit for PCB No 153 – 0,03 ng/g
milk and 0,25 ng/g oil).
The accuracy of the determination of specified congeners in milk (between 87.3% and
94,1% ) is better than in oil and fish (between 66,4% and 77,6%).
In the determination of the linearity of the method increased amounts of each congener
were used for spiking in order to obtain concentration around 50, 100, 150 and 200 % of these
found in milk and fish samples. The correlation coefficients of calibration equations of
particular congeners ranged between 0,9878 (PCB No 105 in milk) and 0,9994 (PCB No 128
in oil).
Accuracy and precision of both analytical procedures were confirmed by the results of
analysis of certified powered milk (CRM-450) and herring tissue from Stockholm University.
References
1. Jones, K.C., P. de Voogt (1999) Persistent Organic Pollutants: State of the Science.
Environ. Pollut. 100, 209-221.
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Persistent, Bioaccumulative and Toxic Chemicals I – Fate and Exposure (Editors:
Lipnick R.L., Hermens J.L.M., Jones K.C. and Muir D.C.) ACS Symposium Series:
772; American Chemical Society, Washington DC., pp. 85-98
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the southern Baltic Sea – Trends and Fate. Sci. Total Environ. 280, 1-15
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the Method of Polychlorinated Biphenyls Determination in Milk Samples in Fifth
International Symposium and Exhibition on Environmental Contamination in Central
and Eastern Europe –Symposium Program Prague 2000, Abstract 521, 206-207.
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