DEVELOPMENT OF A REFERENCE MATERIAL FOR RESIDUES OF CHLORFLUAZURON AND FLUAZURON IN BEEF FAT ACSL CRM-3 .1. PREPARATION, HOMOGENEITY AND STABILITY

A beef fat sample was prepared and tested as candidate reference mater ial for the pesticides chlorfluazuron (CFZ) and fluazuron (FZN). An an alytical method employing HPLC with UV absorbance detection was develo ped for homogeneity and stability testing. The material consisted of b eef fat spiked with acetone solutions of CFZ and FZN to achieve concen trations close to 1.0 mg/kg for each compound. The coefficients of var iation of 7 analyses carried out to test between-jar homogeneity were 1.8% and 2.3% for FZN and CFZ, respectively. No instability of CFZ was detected over a three month period. The candidate reference material was found to be suitable for certification by interlaboratory testing.