Establishment of certified reference material for pesticides using mass balance and differential scanning calorimetry: acynonapyr, flometoquin, bifenazate, and metabolite bifenazate diazene
Pesticides play a crucial role in modern agriculture as crop protectants for safeguarding crops and enhancing productivity. However, pesticide residues in food can be exposed to the human body and present a potential threat. Governments have implemented regulations on pesticide use and maximum residual levels in each agrifood to address this concern. In this study, certified reference materials (CRMs) of four candidate materials, namely acynonapyr, flometoquin, bifenazate, and bifenazate diazene were established by the interlaboratory collaboration with three institutions following ISO Guideline 35:2017. The CRMs were characterized using both mass balance (MB) and differential scanning calorimetry (DSC). Using both approaches can complement the limitations of a single method and result in highly accurate and reliable data. Homogeneity tests were conducted to evaluate the uniformity of the CRMs between bottles and within bottle. Furthermore, long- and short-term stability studies were performed at -20 ℃ for 12 months, and at 4 ℃, 25 ℃/60% relative humidity (RH), and 40 ℃/75% RH for 3 months. The test results confirmed that candidate CRMs are homogeneous and stable at the tested conditions and durations. Given the involving multiple laboratories, the pooled uncertainty was accounted for while estimating the expanded uncertainty. The accomplished CRMs offer the following purities and expanded uncertainties: acynonapyr 99.3% ± 0.6% (𝑘=2.262), flometoquin 98.9% ± 0.1% (𝑘=2.306), bifenazate 99.7% ± 1.2% (𝑘=4.303), bifenazate diazene 99.9% ± 0.7% (𝑘=2.776), respectively. The four CRMs were successfully established and can be reliable references for pesticide residue analysis in national testing agencies.
