UHPLC-MS/HRMS method for the quantitation of pyrithione metabolites in human urine.

Pyrithione glucuronide (PTG) and 2-thiopyridine glucuronide (ThPG) have been reported to be the major urinary metabolites in multiple animal species following administration of zinc pyrithione (ZnPT). However, the formation of these metabolites has never been confirmed in humans. A simple and rugged ultra-high-performance liquid chromatography high resolution mass spectrometry (UHPLC-MS/HRMS) method was developed and validated for the quantification of PTG and ThPG to investigate human metabolism of pyrithione following topical application of ZnPT as a shampoo. A UHPLC-MS/HRMS method was required due to the matrix interferences that were observed with the typical industry standard HPLC/tandem mass spectrometry (LC-MS/MS) methodology based on nominal mass triple quadrupole (QQQ) platform approach. Using UPLC-MS/HRMS, both PTG and ThPG were identified in human urine following topical application of ZnPT. The presence of these human urinary metabolites of pyrithione are consistent with findings from earlier studies in multiple animal species and suggest the metabolism of pyrithione is similar amongst those mammalian species studied.

Phase transformation induced mechanochromism in a platinum salt: a tale of two polymorphs.

Red crystals of [Pt(tpy)Cl]NO3·HNO3 show mechanochromic behaviour turning yellow when pressure is applied. The electronic character and spectroscopic signature of the red and yellow polymorphs change as a result of slipping of the molecular stacking planes in the solid state. The slippage alters the PtPt intermolecular distances from a linear stacked motif with <3.5 Å separations in the red polymorph to a less stacked motif of alternating short intradimer and long interdimer interactions in the yellow polymorph.

Probabilistic determination of the ecological risk from OTNE in aquatic and terrestrial compartments based on US-wide monitoring data.

OTNE [1-(1,2,3,4,5,6,7,8-octahydro-2,3,8,8-tetramethyl-2-naphthyl)ethan-1-one; trade name Iso E Super] is a fragrance ingredient commonly used in consumer products which are disposed down the drain. This research measured effluent and sludge concentrations of OTNE at 44 US wastewater treatment plants (WWTP). The mean effluent and sludge concentrations were 0.69 ± 0.65 µg/L and 20.6 ± 33.8 mg/kg dw respectively. Distribution of OTNE effluent concentrations and dilution factors were used to predict surface water and sediment concentrations and distributions of OTNE sludge concentrations and loading rates were used to predict terrestrial concentrations. The 90th percentile concentration of OTNE in US WWTP mixing zones was predicted to be 0.04 and 0.85 µg/L under mean and 7Q10 low flow (lowest river flow occurring over a 7 day period every 10 years) conditions respectively. The 90th percentile sediment concentrations under mean and 7Q10 low flow conditions were predicted to be 0.081 and 1.6 mg/kg dw respectively. Based on current US sludge application practices, the 90th percentile OTNE terrestrial concentration was 1.38 mg/kg dw. The probability of OTNE concentrations being below the predicted no effect concentration (PNEC) for the aquatic and sediment compartments was greater than 99%. For the terrestrial compartment, the probability of OTNE concentrations being lower than the PNEC was 97% for current US sludge application practices. Based on the results of this study, OTNE concentrations in US WWTP effluent and sludge do not pose an ecological risk to aquatic, sediment and terrestrial organisms.

Aquatic toxicity structure-activity relationships for the zwitterionic surfactant alkyl dimethyl amine oxide to several aquatic species and a resulting species sensitivity distribution.

Amine oxide (AO) is a cationically charged surfactant at environmental pH and has previously been assessed in the OECD (Organization for Economic Cooperation and Development) High Production Volume (HPV) chemicals program. Typical of cationic chemicals, AO is highly aquatically toxic. In this study we vastly improve the knowledge of AO toxicity by developing acute Quantitative Structure Activity Relationships (QSARs) for an alga (Desmodesmus subspicatus), an invertebrate (Daphnia magna) and a fish (Danio rerio) using the appropriate array of OECD Test Guidelines. A chronic toxicity QSAR was also determined for the most sensitive taxon, Desmodesmus. Pure AO spanning the chain lengths of C8 to C16 were tested individually with trace analytical confirmation of exposures in all tests. The QSARs were all of high quality (R2 0.92-0.98) with slopes ranging from -0.338 to -0.484. QSARs were then used to normalize toxicity outcomes for a larger, previously published data set used in HPV, European REACH (Registration, Evaluation, and Authorization of Chemicals), and peer reviewed publications. Two additional species, Lemna gibba (macrophyte) and Ankistrodesmus falcatus (alga) were studied in exposures to dodecyl (C12) AO to provide sufficient taxonomic diversity to conduct a Species Sensitivity Distribution (SSD) analysis. The SSD 5th percentile hazardous concentration (HC5) to C12 AO was found to be 0.052mg/L which is similar to an existing AO 28-d, 3-community periphyton community bioassay normalized to C12 AO (No-observed-effect-concentration or NOEC=0.152mg/L). The statistical properties of the SSD was probed suggesting that new studies of additional taxa would be required that were at least 10-fold more sensitive than the most sensitive taxon to move the HC5 lower by a factor of 3. The overall AO hazard assessment suggests a large margin of safety relative to published environmental exposure data.