A method for the determination of Mirex (1, 1a, 2, 2, 3, 3a, 4, 5, 5a, 5b, 6-dodecachlorooctahydro-1, 3, 4-metheno-1H-cyclobuta [cd] pentalene) and 1, 2, 4, 5-tetrabromobenzene (TBB) in human milk samples was developed. The extracts from these samples with hexaneether-ethanol solvent were partitioned with hexane-acetonitrile, cleaned-up by Florisil column chromatography, and determined by selected ion monitoring (SIM). The SIM analyses were carried out under the following conditions: TBB, m/z 392, 394 on 2.5% Bentone 34+2.5% DC 200 (210°C), or 2% OV-1 (190°C) column; Mirex, m/z 272, 274 and 546 on 2% OV-1 column (240°C). Recoveries of TBB and Mirex added to cow's milk (10g) were as follows: TBB 79.4% (10ng added), 83.4% (100ng added); Mirex 74.6% (10ng added), 72.5% (100ng added).
Human milk samples were collected from women living in the vicinity of Tokyo Metropolitan area. The residue levels of Mirex and TBB in these samples were ca. 1ng/g and 3ng/g, respectively, on a milk fat basis.