Tetrodotoxin (TTX) is an extremely potent marine biotoxin. An analytical method was developed for both trace contamination and extremely high levels of TTX in gastropods by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with clean-up of cation exchange solid phase extraction (SPE) in this study. The limit of detection (LOD) in the sample matrix was 0.5 μg/kg. With the calibration of a screened internal standard (validamycin, IS), the linear range was 0.1–100 ng/mL (1.5–1500 μg/kg in sample matrix) with a correlation coefficient of r² > 0.999. The average recoveries at three spiking levels (1.5 μg/kg, 44 μg/kg, and 1500 μg/kg) were 82.6–94.4% with relative standard deviations (RSDs) less than 8.4%. TTX levels in seven gastropods (741 samples) were studied. The contamination and analogues in Neverita didyma (N. didyma, 565 samples collected in Zhejiang province, China, from 2016 to 2022) were first reported. The detection rate of TTX in N. didyma was 34.2%. The average concentration was 23.1 μg/kg, and the maximum value was 2327 μg/kg. The time distribution study indicated that high contaminations of TTX occurred from May to August for N. didyma.

A certified reference material (CRM) for aflatoxins (AFTB1, AFTB2, AFTG1, AFTG2) and zearalenone (ZEN) in corn/peanut blended vegetable oil (GBW(E)100863) was developed to address the critical need for matrix-specific reference materials in mycotoxin analysis. The CRM was prepared by blending naturally contaminated corn and peanut oils, followed by homogenization, sterilization, and sub-packing. Homogeneity and stability studies were conducted using high-performance liquid chromatography isotope-dilution tandem mass spectrometry with a dilute-and-shoot pretreatment process. The CRM demonstrated excellent homogeneity and stability, with no significant degradation observed under either short-term (65 °C for 14 days) or long-term (25 °C for 12 months) storage conditions. An inter-laboratory comparison involving six authoritative laboratories confirmed the CRM’s accuracy and reliability, with recovery rates ranging from 90.3% to 97.3% and low relative standard deviations (RSDs) of 3.79% to 7.99%. The CRM provided a robust metrological tool for mycotoxin analysis in complex oil matrices. This study not only enriches the national reference materials library but also supports food safety initiatives by facilitating accurate and reliable mycotoxin detection in vegetable oils, thereby enhancing regulatory compliance and public health protection.

The separation and simultaneous quantitation of diastereomers of DL-α-tocopherol, eight tocol forms, and retinols (trans and cis) have been conducted by reversed-phase liquid chromatography followed by solid-phase extraction. A chiral silica stationary phase modified with polysaccharide derivative on the monodisperse macroporous silica gel (Unichiral OD-5H column, 150mm×4.6mm, 5μm, NanoMicro Technology Co., Ltd.) was employed for eluting each target compound. Instead of conventional solvent extract, a green and eco-friendly solid-phase extraction column, packing with nonpolar polystyrene divinylbenzene, was optimized in terms of capacity and solvent used in steps. Validation of the method was examined and confirmed to be satisfactory, with excellent linearity regression (r>0.9999), acceptable accuracy (74.66112.92), and precision (0.2010.52) results. Limit of detection ranged from 0.05mg·kg⁻¹ (retinols) to 0.4mg·kg⁻¹ (tocols). The method was checked by infant formula reference material SRM 1849a as well, which illustrated good agreement of mass fraction with certified value and enriched the important isomer data.