Challenges in the Analyses of Organophosphate Esters

Organophosphate esters (OPEs) have been subject to considerable scientific and public scrutiny in recent years. The combination of their physicochemical characteristics and lack of standard analytical methods has resulted in growing concerns with respect to the validity of OPE concentrations reported in the literature. The goal of this study was to address the analytical challenges in analyses of OPEs by comparing the precision and accuracy of data generated for individual target analytes by different laboratories. Eleven international research laboratories were recruited in this study, and a total of 16 OPEs, chosen among the most frequently reported ones, were targeted. Results demonstrate the participating laboratories had generally good to very good consistency for the suite of OPEs analyzed, but accuracy was found to be a problem for several OPEs and laboratories. Methods utilized for the quantification of tri-<i>m</i>-tolyl phosphate, tri-<i>p</i>-tolyl phosphate, and tris­(2-butoxyethyl) phosphate performed worst overall, as highlighted by their zeta-scores, suggesting that interpretation and comparison of results for these OPEs should be made with caution and that current analytical methods may need to be improved. Liquid chromatography and tandem mass spectrometry performed best for both precision and accuracy

Dechlorinated Analogues of Dechlorane Plus

Degradation products of the chlorinated additive flame retardant Dechlorane Plus (DP) have been discovered globally. However, the identity of many of these species remains unknown due to a lack of available analytical standards, hindering the ability to quantitatively measure the amounts of these compounds in the environment. In the present study, synthetic routes to possible dechlorinated DP derivatives were investigated in an effort to identify the environmentally significant degradation products. The methano-bridge chlorines of <i>anti</i>- and <i>syn</i>-DP were selectively replaced by hydrogen atoms to give six new hydrodechlorinated DP analogues. The identity and absolute configuration of all of these compounds were confirmed by GC-MS, NMR spectroscopy, and X-ray diffraction studies. These compounds were observed in sediment samples from streams and rivers in relatively rural areas of Ontario and are thus environmentally relevant

Characterization and Biological Potency of Mono- to Tetra-Halogenated Carbazoles

This paper deals with the characterization and aryl hydrocarbon receptor (AhR) agonist activities of a series of chlorinated, brominated, and mixed bromo/chlorocarbazoles, some of which have been identified in various environmental samples. Attention is directed here to the possibility that halogenated carbazoles may currently be emitted into the environment as a result of the production of carbazole-containing polymers present in a wide variety of electronic devices. We have found that any carbazole that is not substituted in the 1,3,6,8 positions may be lost during cleanup of environmental extracts if a multilayer column is utilized, as is common practice for polychlorinated dibenzo-<i>p</i>-dioxin (dioxin) and related compounds. In the present study, ¹H NMR spectral shift data for 11 relevant halogenated carbazoles are reported, along with their gas chromatographic separation and analysis by mass spectrometry. These characterization data allow for confident structural assignments and the derivation of possible correlations between structure and toxicity based on the halogenation patterns of the isomers investigated. Some halogenated carbazoles exhibit characteristics of persistent organic pollutants and their potential dioxin-like activity was further investigated. The structure-dependent induction of CYP1A1 and CYP1B1 gene expression in Ah-responsive MDA-MB-468 breast cancer cells by these carbazoles was similar to that observed for other dioxin-like compounds, and the magnitude of the fold induction responses for the most active halogenated carbazoles was similar to that observed for 2,3,7,8-tetrachlorodibenzo<i>-p-</i>dioxin (TCDD). 2,3,6,7-Tetrachlorocarbazole was one of the most active halogenated carbazoles and, like TCDD, contains 4 lateral substituents; however, the estimated relative effect potency for this compound (compared to TCDD) was 0.0001 and 0.0032, based on induction of CYP1A1 and CYP1B1 mRNA, respectively