Vitamin D is the name given to a series of compounds with antirachitic activity. In this study, we developed a method for quantification of the common Vitamin D, ergocalciferol (vitamin D₂), and cholecalciferol (vitamin D₃), in edible fungus by reversed-phase two-dimensional liquid chromatography. The sample was saponified by KOH ethanol solution and extracted with ethyl acetate and n-hexane. After reconcentration, the sample was directly injected for instrumental analysis. The results showed that the spiking recoveries of vitamin D₂ and vitamin D₃ were 80.4–93.8% and 82.3–92.0%, respectively. The relative standard deviations (RSDs) were all less than 5%. Comparing to the results of isotope dilution liquid chromatography tandem mass spectrometry, there were no significant differences ( ). The method was applied for testing vitamin D₂ and D₃ in 9 kinds of edible mushrooms. It showed that vitamin D₃ was not detected. The content of vitamin D₂ ranged from 0.11 μg/100 g to 123 μg/100 g. The content of vitamin D₂ in dried mushroom was the highest, while that in fresh mushroom was the lowest. The limit of quantification was 0.025 μg/100 g.

An isotope-dilution liquid chromatography tandem mass spectrometry method was established for the determination of vitamin B₁₂ in milk and dairy products. The samples were spiked with stable isotope-labeled vitamin B₁₂ and digested by pepsin and amylase. The various forms of cobalamin were transformed to cyanocobalamin by potassium cyanide after they were released from the enzymatically digested samples. Cyanocobalamin was extracted and purified by an immunoaffinity SPE cartridge and then measured in multiple reaction monitoring mode (MRM). The linear correlation coefficient (R²) of this method was greater than 0.999 in the range of 2100ng/mL. The detection limit and the quantification limit were 0.5μg/kg and 1.0μg/kg, respectively. The spiked recoveries ranged from 92.0 to 99.4 at the three spiked levels with the relative standard deviation (RSD) between 1.89 and 4.51. The measured results of NIST SRM1849a and NIST SRM1869a by the current method are all within the reference value range. The Z value was 0.8 during participating in the FAPAS proficiency test using the developed method in 2021. The method is simple, rapid, accurate, and sensitive, and it is suitable for the determination of vitamin B₁₂ in different types of milk and dairy products such as whey powder, whole milk powder, pure milk, fermented milk, infant formula, and prescription food for special medical purposes.

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.