In this study, a rough, cheap, easy-made wooden-tip-based solid-phase microextraction (SPME) probe was first developed for simultaneous determination of 4 nitrofuran metabolite derivatives in complex food matrices via LC-MS/MS. A simple dip-coating method was used to coat wooden tips with biocompatible polyacrylonitrile (PAN) and N-vinylpyrrolidone-co-divinylbenzene, also known as HLB particles, which served as the extractive substrate in the proposed device. Compared with the traditional solid-phase extraction (SPE) method, the proposed device shortens sample clean-up time, reduces solvent consumption, and decreases testing costs. In addition, the main parameters affecting the SPME procedure efficiency were investigated in detail and the optimal conditions were found. The method was validated using three different food matrixes (pork, croaker, and honey) by spiking with the four metabolites at 0.5, 1.0, and 5.0 μg/kg, as well as their internal standards. The average recovery of all nitrofuran metabolite derivatives ranges from 97.4–109.5% (pork), 87.5–112.7% (croaker), and 98.6–109.0% (honey). Relative standard deviations were all <10% for intraday and interday precision. The values of limit of detection and limit of quantification were, respectively, ranging from 0.011 to 0.123 and 0.033 to 0.369 μg/kg (pork), 0.009 to 0.112 and 0.027 to 0.339 μg/kg (croaker), and 0.010 to 0.131 and 0.030 to 0.293 μg/kg (honey). The presented method was applied to the analysis of real positive samples.

A rapid, effective, and reliable method for the simultaneous detection of 20 neonicotinoids and their metabolites in infant foods has been developed using liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). To improve the accuracy and precision of the method, different extraction solvents, extraction methods, and adsorbents were evaluated to achieve a better recovery and clean-up effect. Under optimized conditions, the samples were extracted with acetic acid acidified acetonitrile/ethyl acetate by ultrasonication, and then were cleaned with reduced graphene oxide@Fe3O4 (rGO@Fe3O4) and primary and secondary amine (PSA) through a QuEChERS step. A matrix-matched calibration method was applied for quantification. Relative standard deviations were all <15% for intraday and interday precision. The values of limit of detection and limit of quantification were ranging from 0.02–0.35 μg·kg−1 and 0.1–1.0 μg·kg−1, respectively. The presented method was applied to the analysis of real samples.