Determination of 107 Pesticide Residues in Wolfberry with Acetate-buffered Salt Extraction and Sin-QuEChERS Nano Column Purification Coupled with Ultra Performance Liquid Chromatography Tandem Mass Spectrometry.

A multi-residue method for the determination of 107 pesticide residues in wolfberry has been developed and validated. Similar pretreatment approaches were compared, and the linearity, matrix effect, analysis limits, precision, stability and accuracy were validated, which verifies the satisfactory performance of this new method. The LODs and LOQs were in the range of 0.14-1.91 µg/kg and 0.46-6.37 µg/kg, respectively. The recovery of analytes at three fortification levels (10 µg/kg, 50 µg/kg, 100 µg/kg) ranged from 63.3-123.0%, 72.0-118.6% and 67.0-118.3%, respectively, with relative standard deviations (RSDs) below 15.0%. The proposed method was applied to the analysis of fifty wolfberry samples collected from supermarkets, pharmacies and farmers' markets in different cities of Shandong Province. One hundred percent of the samples analyzed included at least one pesticide, and a total of 26 pesticide residues was detected in fifty samples, which mainly were insecticides and bactericide. Several pesticides with higher detection rates were 96% for acetamiprid, 82% for imidacloprid, 54% for thiophanate-methyl, 50% for blasticidin-S, 42% for carbendazim, 42% for tebuconazole and 36% for difenoconazole in wolfberry samples. This study proved the adaptability of the developed method to the detection of multiple pesticide residues in wolfberry and provided basis for the research on the risks to wolfberry health.

Determination of residual levels of naloxone, yohimbine, thiophanate, and altrenogest in porcine muscle using QuEChERS with liquid chromatography and triple quadrupole mass spectrometry.

A quick, easy, cheap, effective, rugged, and safe QuEChERS (method) was used for the simultaneous detection of four veterinary drug residues, namely naloxone, yohimbine, thiophanate, and altrenogest, in porcine muscle, using liquid chromatography with electrospray ionization triple quadrupole tandem mass spectrometry. Because of the unavailability of a suitable internal standard, matrix-matched calibrations were used for quantification, with determination coefficients ≥ 0.9542. The accuracy (expressed as recovery %) ranged from 60.53 to 83.25%, and the intra- and interday precisions (expressed as relative standard deviations) were <12%. The limits of quantification were 5, 0.5, 2, and 5 ng/g for naloxone, yohimbine, thiophanate, and altrenogest, respectively. Samples purchased from local markets in Seoul, Republic of Korea, revealed no traces of the target analytes. The developed method described herein is sensitive and reliable and can be applied to quantify the tested veterinary drugs in animal tissues.