Development of a new matrix certified reference material for metronidazole in egg powder

Abstract

Due to the potential health risks and hazards associated with the intake of metronidazole, several governments and consumers have become increasingly concerned about the quality and safety of food in the recent years. Since it is not possible to avoid the side effects of metronidazole, immense efforts are being taken to appraise and monitor its concentration in feed in order to ensure the safe consumption of food. However, simple certified reference materials (CRMs) for the quality control and quality assurance of metronidazole are still lacking. Thus, the first matrix CRM for metronidazole was developed from egg powder. This paper presents the complete process of the development of a CRM for metronidazole in egg powder, including sample preparation, homogeneity and stability studies, and the uncertainty assessment. The egg samples were taken from hens that took metronidazole orally. The matrix CRM developed was quantified using isotope dilution high-performance liquid chromatography coupled with tandem mass spectrometry. Concurrently, in order to support the certification study, an interlaboratory contrast study involving eight expert laboratories was implemented. The bulk material was bottled in 4 g portions. While the stability of the CRM was monitored at −20 °C for 13 months, at −4°C, 20 °C, and 40 °C for 9 days. During the monitoring period, the matrix CRM candidate was found to be stable at all temperatures.