Determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin in goat milk and tissues by glass capillary gas chromatography and medium resolution mass fragmentography

Abstract

An analytical method has been developed for the study of the elimination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) by lactation and its determination in various tissues of goat. The method is based on the alkaline hydrolysis of milk, liver, fat, muscle, blood, faeces and urine samples, extraction with n-hexane, treatment with sulphuric acid-saturated silica gel, chromatographic clean-up on silica gel and alumina micro-columns, and glass capillary gas chromatography-medium resolution mass fragmentography (resolution 2000). 1,2,3,4-Tetrachlorodibenzo-p-dioxin is used as the internal standard, the concentration of TCDD being determined from the calibration curve calculated from the peak heights of TCDD and the internal standard in the mass fragmentogram of the ion m/e 321.9. The minimum detectable level of TCDD varied from 0.5 to 1 ppt in milk (20 g), 1 ppt in muscle (10 g), 1 to 2 ppt in liver (10 g) and 2 to 5 ppt in fat (1 g). The TCDD level in the control animals was below the detection limit. The recovery of TCDD varied between 73 and 100%. The reproducibility of the analyses expressed as the relative standard deviation, was 5.1% at the 500-ppt level and 3.6% at the 20-ppt level. The reproducibility of the gas chromatographic-mass fragmentographic analysis was 2.4% (50-100 pg).