Comparison of Laboratory Techniques for the Determination of Pesticide Residues in Milk

Of the techniques available for specific pesticide residues, fly bioassay is non-specific and not very sensitive; total organic chloride determination also lacks specificity; the AOAC colorimetric method produces variable results, lacks sensitivity for low levels of residues, and does not cover the range of residues likely to be present in milk. Chromatographic tests are most satisfactory. Microcoulometric gas chromatography has many advantages but requires a skilled analyst. Electron-capture gas chromatography is promising but has not been fully developed. The Mills test, which combines column cleanup with identification by paper chromatography, is a rapid, practical screening test. In a collaborative comparison of the chromatographic procedures, microcoulometry tended to give higher results than the Mills test; electron-capture gave lower results than the other two methods. Details of all tests must be followed closely for good results.