Novel Coffee Certified Reference Material for Ochratoxin A, B, and C

A coffee-certified reference material (CRM) for ochratoxin A, B, and C (OTA, OTB, and OTC) was created to improve the precision and reliability of these toxins. A collection of 100 bottles (each containing 10 g) of the CRM candidate for OTA, OTB, and OTC was produced by applying a mixed standard solution of OTA, OTB, and OTC to moderately roasted beans that subsequently ground and homogenized. Moreover, considering the intricate matrix interference in coffee, a rapid and sensitive method for OTA, OTB, and OTC in coffee was developed with minimal matrix effects. This approach employed liquid chromatography–tandem mass spectrometry and mixed purification materials (C18 and hydroxylated multi-walled carbon nanotubes (MWCNTs), OH-MWCNTs) for the analysis. Based on the standards GB/T 15000.3-2008/ISO Guide 35: 2017, the CRM demonstrated robust uniformity and stability when stored for 14 d at 4, 20, and 40 °C, and 12 months at −20 °C. Eight laboratories were employed to characterize the CRM. The certified values for OTA, OTB, and OTC in coffee were established to be 15.2 ± 0.4, 12.8 ± 0.4, and 3.4 ± 0.1 μg/kg (with a coverage factor k = 2, representing an approximate 95% confidence interval).