Determination of nitrofurazone in fluid milk and dairy powders. Part 1: An international pilot study

An international pilot study involving five laboratories evaluated the performance of a method intended as a joint ISO/IDF international standard for the analysis of fluid milk and powdered dairy products for intact nitrofurazone down to levels of 1 ng g(-1) . After first establishing that nitrofurazone remains stable to heat treatments in excess of pasteurisation conditions, fluid milk samples that were deliberately spiked with nitrofurazone at low ng g(-1) levels were measured by the laboratories, despite the milk containing no preservatives and, in some cases, being stored at ambient temperature for several months. Commercial whole milk powder and milk protein concentrate, deliberately spiked with low ng g(-1) levels of nitrofurazone, were also analysed by the participating laboratories. For both liquid and powdered dairy samples containing nitrofurazone, laboratories could detect and confirm the presence of nitrofurazone. The within-laboratory repeatability and between-laboratory reproducibility estimates were consistent with the Horwitz ratio. (C) 2019 Elsevier Ltd. All rights reserved.