QUALITY ASSURANCE OF ISOMER-SPECIFIC ANALYSIS OF PCBS IN SERUM

The Biomonitoring Laboratory of the Finnish Institute of Occupational Health has analysed PCB's in serum isomer-specifically for more than t en years for the purpose of biomonitoring PCB exposure from different sources: environmental, accidental (short-term occupational exposure) and occupational exposure (condensator manufacture and hazardous waste disposal). Internal quality control, in which the analytical performa nce for each isomer was separately followed from spiked control specim ens in each analytical series, demonstrated an imprecision that is in average 15% for less chlorinated isomers and 28% for more chlorinated individual PCB isomers at a concentration level of aprox 2.5 mu g/L Th e internal quality control scheme reveeled an important contribution t o the analytical error, The external quality assurance for the verific ation of analytical trueness demonstrated that >85% of the analytical results were within the target range specified by the organiser of the scheme. (C) 1997 Elsevier Science Ltd.