INFLUENCE OF RELATIVE RESPONSE FACTOR IN THE DETERMINATION OF ORGANICMICROCONTAMINANTS WITH ISOTOPICALLY LABELED STANDARDS

The use of isotopically labeled internal standards in the analysis of organic microcontaminants entails the determination of relative respon se factors (RRFs) of the unlabeled with respect to the labeled compoun ds. RRFs were measured daily during 28 replicate polychlorobiphenyl (P CB) analyses on two different sets of samples. Daily RRFs allowed more precise results to be attained than those provided by mean RRFs, the latter being the mean of all the daily RRFs obtained during the same s eries of analyses. Analytical applications to food matrices are presen ted, including the PCB contamination profile of an olive oil and that found in a matrix of Italian national mean diet. Based on the latter s ample, also the polycyclic aromatic hydrocarbon (PAH) daily intake of Italians is assessed. Seven PAHs are determined.