Practical steps to improve the quality control of the chromatography for chlorobiphenyl and organochlorine pesticide analysis

A study of the variability of the final determination of chlorinated biphenyls (CBs) and organochlorine pesticides (OCPs) using a gas chromatograph with an electron capture detector (GC-ECD) was carried out using both archived data, and data obtained following the optimization and validation of the GC-ECD. The precision and bias of the laboratory's historical data lay outside the recommended limits of the ICES and QUASIMEME intercomparison exercises, and for those following GC optimization the repeatability was greatly improved. New control limits were set to international guidelines. The steps taken to achieve greater precision and accuracy from a determination are detailed.