Determination of 142 pesticides in fruit- and vegetable-based infant foods by liquid chromatography/electrospray ionization-tandem mass spectrometry and estimation of measurement uncertainty.

A liquid chromatographic/electrospray ionization-tandem mass spectrometric method was developed and validated to determine 142 pesticides in fruit- and vegetable-based infant foods, including apples, apples and bananas, pears, bananas, apple juice, peas, sweet potatoes, creamed corn, squash, and carrots. Pesticides were extracted from infant foods by using the procedure known as the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. Quantification was based on matrix-matched standard calibration curves with the use of an isotopically labeled standard or a chemical analogue as the internal standard to obtain method accuracy. The method performance parameters, including overall recovery, intermediate precision, and measurement uncertainty, were evaluated on the basis of a nested design. The performance results were calculated by using a compiled SAS program that provided a semiautomated procedure for handling a large number of calculations in a few seconds. In general, the overall recoveries, for spiking levels of 10, 50, and 80 microg/kg, fell in a range of 81-110%, intermediate precisions were <20%, and measurement uncertainties were <40%. Chlorimuron-ethyl, ethofenprox, haloxyfop, naptalam, primisulfuron-methyl, pyridalyl, pyridate, quizalofop, and tebufenozide were the method problematic pesticides that had large measurement uncertainty (>40%) due to low recovery andlor poor repeatability. The method provided an analytical range of 1-100 microg/kg with the lowest concentration level at 1 microg/kg for all pesticides (signal-to-noise ratio of >10), except for aclonifen at 5 microg/kg.