Identification of chlorinated methoxybiphenyls as contaminants in fish and as potential interferences in the determination of chlorinated dibenzo-p-dioxins

Determination of part-per-trillion levels of polychlorinated dibenzofurans and dioxins in environmental samples

“…Determinations of PCDDs, PCDFs, and nonortho PCBs in environmental samples at levels below 1 pptr are particularly susceptible to interferences and possible false-positive results as a consequence of the likely occurrence of a large variety of polychlorinated aromatic cocontaminants and because full-scan mass spectrometric analyses are usually unattainable. More than a dozen families of such compounds are recognized as potential interferences in these types of analyses (35,58), including DDE and DDT and polychlorinated members of the following compounds: biphenyl (59), methoxybiphenyls (60), hydroxybiphenyls, diphenyl ether (61), methoxydiphenyl ethers, hydroxydiphenyl ethers (62), benzyl phenyl ether (63), naphthalene, biphenylene, phenylbenzoquinone (64), xanthene, and bis(phenoxy)methane (65). Most of these families of compounds have the potential to interfere with and produce false-positive results in determinations of PCDDs and PCDFs even in HRMS (35).…”

Isomer-selective determination of tetrachlorodibenzo-p-dioxins using hydroxyl negative ion chemical ionization mass spectrometry combined with high-resolution gas chromatography

“…The determination of 2,3,7,8-TCDD by OH" NICI is then only negligibly interfered with by large excesses of PCB which represents the worst case (no or insufficient cleanup). Chlorinated methoxybiphenyls and benzyl phenyl ethers are also described as possible interferences (34,35). Since these compounds are not commercially available, no further investigations could be carried out to investigate their OH" NICI mass spectra.…”

Analysis of fish for 2,3,7,8-tetrachlorodibenzo-p-dioxin by electron capture capillary gas chromatography

“…A 50-cm column was obtained by connecting two 25-em columns in series. The columns were eluted at 45 "C under these mobile phase conditions: PSM-GOS, hexane/methanol/methylene chloride (93/5/2, v/v/v) at 1.0 mL/min flow rate; (2-8, acetonitrile/water (75/25, v/v) at 2.4 mL/min flow rate; (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18), 100% acetonitrile at 1.2 mL/min flow rate. Each mobile phase was vacuum degassed while being stirred magnetically at room temperature before use.…”

“…The monitored ions (m/z) included 257, 259, and 261 of the TCDD fragment ion cluster (loss of COCI•); 320, 321, 322, 324, and 326 of the TCDD molecular ion cluster; and 332 and 334 for the [13C]-2378-TCDD internal standard. In addition, m/z 305 and 307 ions were monitored to detect the presence of methoxytetrachlorobiphenyls, which have been found in fish, and which could interfere with the TCDD molecular ion region (10).…”