Extraction of 3,4,4'-Trichlorocarbanilide from Rat Fecal Samples for Determination by High Pressure Liquid Chromatography-Tandem Mass Spectrometry.

Triclocarban (3,4,4'-Trichlorocarbanilide; TCC) in the environment has been well documented. Methods have been developed to monitor TCC levels from various matrices including water, sediment, biosolids, plants, blood and urine; however, no method has been developed to document the concentration of TCC in fecal content after oral exposure in animal studies. In the present study, we developed and validated a method that uses liquid extraction coupled with HPLC-MS/MS determination to measure TCC in feces.

Transplacental passage of antimicrobial paraben preservatives.

Parabens are widely used preservatives suspected of being endocrine disruptors, with implications for human growth and development. The most common paraben found in consumer products is methylparaben. To date, no study has examined whether these substances cross the human placenta.

Selectivity control in synergistic liquid-liquid anion exchange of univalent anions via structure-specific cooperativity between quaternary ammonium cations and anion receptors.

Two anion receptors enhance liquid-liquid anion exchange when added to quaternary alkylammonium chloride anion exchangers, but with a striking dependence on the structure of the alkylammonium cation that suggests a supramolecular cooperative effect. Two anion receptors were investigated, meso-octamethylcalix[4]pyrrole (C4P) and the bisthiourea tweezer 1,1'-(propane-1,3-diyl)bis(3-(4-sec-butylphenyl)thiourea (BTU). Whereas synergism is comparatively weak when either methyltri(C(8,10))alkylammonium chloride (Aliquat 336) or tetraheptylammonium chloride is used with the BTU receptor, synergism between C4P and Aliquat 336 is so pronounced that anion exchange prefers chloride over more extractable nitrate and trifluoroacetate, effectively overcoming the ubiquitous Hofmeister bias.

Supramolecular organization of calix[4]pyrrole with a methyl-trialkylammonium anion exchanger leads to remarkable reversal of selectivity for sulfate extraction vs. nitrate.

meso-Octamethylcalix[4]pyrrole (C4P) enhances sulfate selectivity in solvent extraction by Aliquat® 336N, an effect ascribed to the supramolecular preorganization and thermodynamic stability imparted by insertion of the methyl group of the Aliquat cation into the cup of C4P in its cone conformation.

The use of flow-injection analysis with chemiluminescence detection of aqueous ferrous iron in waters containing high concentrations of organic compounds.

An evaluation of flow-injection analysis with chemiluminescence detection (FIA-CL) to quantify Fe(2+) ((aq)) in freshwaters was performed. Iron-coordinating and/or iron-reducing compounds, dissolved organic matter (DOM), and samples from two natural water systems were used to amend standard solutions of Fe(2+) ((aq)). Slopes of the response curves from ferrous iron standards (1 - 100 nM) were compared to the response curves of iron standards containing the amendments.