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A prototype multiresidue method based on fast extraction and dilution of samples followed by flow injection mass spectrometric analysis is proposed here for high-throughput chemical screening in complex matrices. The method was tested for sulfonylurea herbicides (triflusulfuron methyl, azimsulfuron, chlorimuron ethyl, sulfometuron methyl, chlorsulfuron, and flupyrsulfuron methyl), carbamate insecticides (oxamyl and methomyl), pyrimidine carboxylic acid herbicides (aminocyclopyrachlor and aminocyclopyrachlor methyl), and anthranilic diamide insecticides (chlorantraniliprole and cyantraniliprole). Lemon and pecan were used as representative high-water and low-water content matrices, respectively, and a sample extraction procedure was designed for each commodity type. Matrix-matched external standards were used for calibration, yielding linear responses with correlation coefficients (r) consistently >0.99. The limits of detection (LOD) were estimated to be between 0.01 and 0.03 mg/kg for all analytes, allowing execution of recovery tests with samples fortified at ≥0.05 mg/kg. Average analyte recoveries obtained during method validation for lemon and pecan ranged from 75 to 118% with standard deviations between 3 and 21%. Representative food processed fractions were also tested, that is, soybean oil and corn meal, yielding individual analyte average recoveries ranging from 62 to 114% with standard deviations between 4 and 18%. An intralaboratory blind test was also performed; the method excelled with 0 false positives and 0 false negatives in 240 residue measurements (20 samples × 12 analytes). The daily throughput of the fast extraction and dilution (FED) procedure is estimated at 72 samples/chemist, whereas the flow injection mass spectrometry (FI-MS) throughput could be as high as 4.3 sample injections/min, making very efficient use of mass spectrometers with negligible instrumental analysis time compared to the sample homogenization, preparation, and data processing steps.

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The gas-phase ion-molecule chemistry of doubly charged fullerene cations (Cn2+ where n = 46,48, ..., 60 and 70) with neutral oxygen molecules were investigated using a triple quadrupole mass spectrometer. In this paper, we report additions to the fullerene cage structure which result in the formation of GO2+, Cn022+, and CnOj2+ product ions from the Cn2+ reagent ion. In addition, we also report charge-transfer reactions resulting in the production of Cn+ and 0 2 + ions, as well as reactive charge-transfer reactions generating C,O+ and 03+. All of these processes are a result of low energy ion-molecule collisions ( 0 . 1 4 9 eVhb). The normalized intensity of the fullerene products exhibit little dependence on size of fullerene clusters examined. However, the reactivities of the fullerenes are found to be highly dependent on the collision energy and the oxygen pressure within the collision cell.