Metalaxyl is frequently used to protect a variety of crops from fungal diseases. This study aims to establish a method for the determination of metalaxyl in Chinese bayberry, fresh Dendrobium officinale (D. officinale), and dried D. officinale by gas chromatography-tandem mass spectrometry (GC-MS/MS) and further assess dietary risk. The samples were extracted with acetonitrile and purified by the dispersed solid phase extraction method. Chinese bayberry, fresh D. officinale, and dried D. officinale samples were collected from Hangzhou and Zhangzhou in 2021 to clarify metalaxyl residue levels. The metalaxyl was quantitated by the external standard method. In the range of 0.001–0.1 mg L⁻¹, there was good linearity under the optimal conditions. The recoveries ranged from 83.90% to 110.47%, with relative standard deviations ranging from 0.86% to 5.81%. The detection rates in Chinese bayberry, fresh D. officinale, and dried D. officinale were 97.92%, 49.29%, and 50.71%, respectively. The dietary risk of metalaxyl residues in Chinese bayberry, fresh D. officinale, and dried D. officinale was acceptable for consumers.

A simple and sensitive method for the simultaneous quantitation of prohexadione-Ca and uniconazole in the field experiment of Oryza sativa L. and Citrus reticulata Blanco was established using solid-phase extraction (SPE) with polymer anion exchange (PAX) and Florisil followed by LC-MS/MS. The method demonstrated excellent linearity (R² > 0.999 0), trueness (recoveries between 95~105%), precision (CVs between 0.8~12%), sensitivity, and repeatability (LOQ of 0.05 and 0.01 mg/kg, respectively). Residue tests were conducted in the field at 12 representative sites in China, revealing final concentrations of prohexadione-Ca and uniconazole in brown rice, rice hull, and rice straw to be below 0.05 mg/kg, while in whole citrus fruit and citrus pulp, they were below 0.01 mg/kg. These were below the maximum residue limits specified in China. The chronic dietary risks of prohexadione-Ca and uniconazole in rice crops and citrus fruits were calculated to be 0.48% and 0.91%, respectively. Our research suggests that the chronic risk associated with the daily consumption of rice crops and citrus fruit at the recommended dosage is acceptable.