Meconium The matrix-spiked calibration curves were linear for all parent compounds and metabolites with coefficients of linearity greater than 0.981 (Bielawski et al., 2005). Recovery studies were done on spiked meconium at concentrations of 6.25 mg g1 for parent pesticides and 4.15 mg g1 for pesticide metabolites. Recovery ranged from 82.4% to 109.3% for parent pesticides and 72.3% to 108.0% for pesticide metabolites. The LOD for the parent compounds ranged from 0.098 mg g1 for propoxur to 1.56 mg g1 for lindane. Inter-assay variability was o11.4% for all compounds. LODs for pesticide metabolites ranged from 0.312 mg g1 for most compounds, to 4.15 mg g1 for 3,5,6 trichloro-2-pyridinol. Parent pesticides recovery spiked at 6.25 mg g1 ranged from 82.4% to 109.3% and metabolites, spiked at 4.15 mg g1 from 72.3% to 108.0%. For the GC/MS identification of pesticides in the different matrices, the following criteria were strictly followed to ensure the highest sensitivity and specificity of the test: (1) a distinct peak of the pesticide in the chromatogram at the correct retention time (70.03 min) compared to the positive controls, (2) the target and qualifier mass ions were present in the correct ratio range and (3) there was independent agreement among the analytical investigators regarding the identity of the compound.