Determination of 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin in Human Milk at the 0.1-10 Parts-per-Trillion Level: Method Validation and Survey Results

Capillary column high-resolution gas chromatography/highresolution mass spectrometry (HRGC/HRMS) and packed column gas chromatography/high-resolution mass spectrometry (LRGC/HRMS) were evaluated for the analysis of 0.1-10 parts-per-trillion (pptr or pg/g) of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) In 10-g samples of human milk. This was done as a blind study In two laboratories. The regression equations representing the results are y-0.79x + 0.34 and y = 0.65x + 0.06 for the HRGC/HRMS and LRGC/HRMS methods, respectively, where x Is the amount of TCDD added (parts per trillion) and y Is the amount reported (parts per trillion). The limits of detection range between 0.1 and 0.6 pptr and 0.5 and 6.0 pptr for the HRGC/ and LRGC/HRMS methods, respectively. No false positive and only two false negative reports were made for a total of 38 analyses of spiked milk and three analyses of standard solutions. The methods were applied to the analysis of 103 samples of human milk from mothers residing In areas where herbicides containing 2,3,7,8-TCDD had been used. No 2,3,7,8-TCDD could be detected at an overall median detection limit of 2 pptr and a range of 0.1-6 pptr.