Analysis of Pesticides Residues in Fresh Produce Using Buffered Acetonitrile Extraction and Aminopropyl Cleanup with Gas Chromatography/Triple Quadrupole Mass Spectrometry, Liquid Chromatography/Triple Quadrupole Mass Spectrometry, Gas Chromatography/Ion Trap Detector Mass Spectrometry, and GC with a Halogen-Specific Detector

Abstract

A rapid and inexpensive multiresidue method for determining pesticides in fruits and vegetables is presented. Extraction of a 15 g sample with 15 mL acetonitrile was followed by buffering with magnesium sulfate, sodium chloride, sodium citrate dihydrate, and disodium citrate. Acidification with formic acid prior to dispersive cleanup with aminopropyl sorbent and magnesium sulfate was used to stabilize base-sensitive pesticides such as chlorothalonil. Extracts were concentrated to 2 g/mL. Analyses were conducted by GC/ion trap detector MS, GC-halogen-specific detector, and LC/triple quadrupole MS. Accuracy and repeatability for 166 compounds in tomato, potato, and cabbage were 70–120% and <20% CV in 85% of the compounds, respectively. Reproducibility over a 4 month period in multiple commodities and analytical conditions was 62–124%, with CVs better than 30% for 91% of the compounds. Supply cost/sample was reduced 66%, and time to extract a batch of 24 samples was reduced by half compared to the prior method that used a 50 g sample, 100 mL acetonitrile, multiple SPE columns, and additional instrumentation. Additional extraction studies were conducted in tomatoes, oranges, and green beans at 4 g/mL using a GC/MS triple quadrupole system with a programmable temperature vaporization inlet. Recoveries of 70–120% were achieved in 93% of all compounds in green beans, 95% in tomatoes, and 97% in oranges.

Fast pesticide analysis using low‐pressure gas chromatography paired with a triple quadrupole mass spectrometer equipped with short collision cell technology

“…Current methods of analysis for pesticides typically include a sample cleanup step, separation by gas chromatography (GC) or liquid chromatography (LC), and then measurement by a detector. 1 In the case of GC analysis, there are a variety of different detectors available, including the electrolytic conductivity detector (ELCD), 2 halogen specific detector (XSD™), 3 electron capture detector (ECD), 4 and flame photometric detector (FPD). 4 Gas chromatography combined with mass spectrometry (GC–MS) is widely used due to the type of information it provides and its ability to measure complex mixtures.…”

Evaluating gas chromatography with a halogen-specific detector for the determination of disinfection by-products in drinking water

“…The free halogens react with the alkali-sensitized surface of the cathode, which yields an increased thermionic emission that can be measured (Nilsson et al 2001 ; OI Analytical 2017 ). The XSD has successfully been applied for the analysis of chlorinated compounds such as pesticides (Brown et al 2011 ) and halogenated fatty acids (Nilsson et al 2001 ; Zhuang et al 2005 ).…”