Repeatability and reproducibility of determinations of vinyl chloride in foodstuffs

In the spring of 1978 and the autumn of 1979, two collaborative investigations were carried out with the aim of determining the variability of measurements of the vinyl chloride (VC) content of foodstuffs. The first investigation was a preliminary test on VC standards in N,N-dimethylacetamide. The results of this test were considered to be satisfactory. In a second test, lemonade and oil samples spiked with VC were investigated. The methods used were based on the headspace gas-chromatographic technique. The amount of VC added was 3 micrograms/kg for the lemonade sample and 20 micrograms/kg for the oil sample. The external standard method yielded a reproducibility of 53 and 39% and a repeatability of 18 and 17% for the lemonade and oil, respectively. The corresponding findings with the addition method were a reproducibility of 119 and 40% and repeatability of 33 and 9%.