Determination of pesticide residues (>0.5 microgram/L) in soft drinks and sports drinks by gas chromatography with mass spectrometry: collaborative study

A collaborative study was conducted on a method for the measurement of 19 low-level pesticide residues in soft drinks and sports drinks by gas chromatography with mass spectrometry (GC/MS). The pesticide residues determined were 2,4'-dichlorodiphenyldichloroethylene (2,4'-DDE); 2,4'-dichlorodiphenyldichloroethane (2,4'-DDD); 4,4'-dichlorodiphenyldichloroethylene (4,4'-DDE); 2,4'-dichlorodiphenyltrichloroethane (2,4'-DDT); 4,4'-dichlorodiphenyltrichloroethane (4,4'-DDT); 4,4'-dichlorodiphenyldichloroethane (4,4'-DDD); alpha-endosulfan; endosulfan-sulfate; dieldrin; aldrin; ethion; chlorpyrifos; beta-endosulfan; malathion; methyl-parathion; alpha-hexachlorocyclohexane (alpha-HCH); beta-HCH; delta-HCH; and gamma-HCH. Blind fortification solutions containing 4 different levels of pesticide residues (0, 0.1, 0.5, and 1.0 microg/L) were provided to 8 collaborating laboratories who used them to create test samples in 6 matrixes (also provided): 2 colas, a diet cola, a clear lemon-lime soft drink, an orange soft drink, and a sports drink. Reproducibility (RSDR) for all 19 pesticide residues in all matrixes ranged from 7 to 151% at the 0.1 microg/L level, 11 to 121% at 0.5 microg/L, and 14 to 67% at 1.0 microg/L. Repeatability (RSDr), applicable to the diet cola and the sports drink, ranged from 1 to 76% for the 19 pesticide residues at the 0.1 microg/L level, 9 to 38% at 0.5 microg/L, and 9 to 38% at 1.0 microg/L. Recoveries for the 19 pesticide residues in all matrixes ranged from 77 to 645% at the 0.1 microg/L level, 60 to 231% at 0.5 microg/L, and 61 to 146% at 1.0 microg/L. It is recommended that the method be accepted by AOAC as Official First Action with a limit of quantification (LOQ) equal to 0.5 microg/L for 4,4'-DDT; 2,4'-DDT; 2,4'-DDD; 4,4'-DDE; 4,4'-DDD; 2,4'-DDE; aldrin; dieldrin; alpha-endosulfan; endosulfan-sulfate; chlorpyrifos; and ethion, and an LOQ equal to 1.0 microg/L for beta-endosulfan; alpha-HCH; beta-HCH; delta-HCH; gamma-HCH; methyl-parathion; and malathion.