Development of certified reference materials for organic analysis in KRISS to enhance the food safety

Abstract

The production of certified reference materials (CRMs) for the accurate determination of hazardous organic materials in food has been challenging because of the instability of hazardous materials which are measurands and food matrices. It is crucial to identify all conditions necessary for stable CRMs, including the selection of analytes and matrices, sterilization methods, analytical techniques, and storage conditions. Over the past two decades, KRISS has developed CRMs for the analysis of food additives, pesticides, mycotoxins, and antibiotics in various food matrices. Raw materials that were not naturally contaminated were fortified with target analytes, such as kimchi cabbage powder and strawberry powder for the analysis of pesticides and beef powder and chicken powder for the analysis of antibiotics. In the case of CRMs for the analysis of mycotoxins, the raw materials naturally contaminated were obtained; therefore, CRMs were produced without fortification, such as fermented soybean paste (Doen-jang) powder, corn powder, and coffee powder. The CRMs for the analysis of hazardous organic materials in food were not irradiated by gamma rays for sterilization of food matrices because it would cause the degradation of target analytes. Instead, they were stored at -70 ℃ in a deep freezer and long-term stability has been monitored. A beverage CRM for the analysis of food additives was fortified with target analytes, and propionic acid was added as an anti-fungus because the reference materials could not be stored below 0 ℃ and gamma rays irradiation could not be applied. Bottled beverage CRMs with propionic acid were stored in a cold room at 4 ℃ and monitored for stability. For the certification of these CRMs, isotope dilution mass spectrometry (ID-MS) was used with gas or liquid chromatography. Traceability was established by purity assessment of the high-purity chemicals. Experience in CRM production and certification was adopted in the proficiency testing (PT) program coordinated by the Ministry of Food and Drug Safety (MFDS) and the Asia Pacific Metrology Programe-Asia Pacific Laboratory Accreditation Cooperation (APMP-APLAC). KRISS has contributed to improving the analysis reliability of testing laboratories by providing CRMs and RMs for PT programs.