Interlaboratory calibration results of polychlorinated biphenyl analyses in herring

Twenty-three laboratories from 13 countries in continental Europe, Scandinavia, the British Isles, and North America participated in a polychlorinated biphenyl (PCB) Check Sample Program conducted under the auspices of the International Council for Exploration of the Sea (ICES). PCBs were determined in unspiked and spiked (1.00 mg Aroclor 1254/kg oil) herring (Clupea harengus harengus) oil by the participants, each of which used his or her own cleanup and quantitation techniques; a common Aroclor 1254 mixture was used as a standard and a common quantitation technique was used for comparative purposes. Results for the unspiked oil ranged from 0.48 to 3.416 mg PCB/kg oil, while spiked oil results ranged from 0.70 to 3.891 mg/kg. Calculated spike recoveries ranged from 22 to 136%. Serious deficiencies were found in most steps in the procedures. No evidence was found to support the use of a common PCB standard or a common method of calculation using packed column chromatography. The chromatographic stationary phase used appeared to affect the PCB levels obtained. Florisil cleanup adsorbent yielded higher mean results for both unspiked and spiked oils than did alumina. Large coefficients of variation were found (25-50%), the principal source of which was systematic error (interlaboratory).