Gas-Liquid Chromatographic Determination of Technical Chlordane Residues in Food Crops: Interpretation of Analytical Data

Abstract

An interlaboratory investigation of technical chlordane residues in food crops was carried out to determine the most practical and consistent method of reporting results. Using a technical chlordane reference standard, 8 gas chromatographic stationary phases were studied for their resolution capabilities. The best separations were obtained with SE-30 and its OV-1 equivalent. Using these columns and electron capture detection, potatoes and carrots from supervised field experiments were analyzed in duplicate and quantitated by using 4 methods of calculation. The data were statistically treated to determine the precision and bias for each method. Also, 1 sample was analyzed in duplicate on 2 different occasions by 6 laboratories to substantiate the initial conclusions. Based on the criterion of high precision it is suggested that a comparison of total area under the chromatogram of the sample with total area of a standard technical chlordane be the method of quantitation. Only peaks which are common to both standard and sample have any significance in this type of calculation.

Analysis of technical chlordane by gas chromatography/mass spectrometry

“…These isomers are commonly Considered to be the two major components of the mixture and are each reported by the manufacturer to be present in the amount of about 20% of the total weight (19). (including eis-nonachlor and compound "K" However, recent studies indicate that they may constitute only half this amount (20,21). Among the other significant components which have been identified (19,(22)(23)(24) in technical chlordane are cis-and trans-nonachlor (structures V and VI), which logically derive from chlorination of the 2-3 double bond of heptachlor (II).…”