Rapid and simple determination of phthalates in plastic toys by a thermal desorption-GC/MS method.

A thermal desorption (TD)-GC/MS method was applied for the determination of phthalates in plastic children's toys. The method, which does not need any cumbersome sample pretreatment such as solvent extraction, filtration and derivatization, has been proved to be useful not only as a sensitive analytical method to evaluate phthalate concentration in the toys, but also as a rapid and practical screening method to check whether the concentration exceeds the regulatory limit.

Rapid estimation of trace organophosphonate used as a scale inhibitor in aqueous systems by reactive pyrolysis-gas chromatography/mass spectrometry.

The determination of trace organophosphonates which are used in cooling towers as a scale inhibitor usually involves extraction and/or concentration of the target components prior to analysis. The extracts are analyzed using chromatographic or spectroscopic methods. This methodology is not only cumbersome but also results in poor data quality. This work presents a novel approach for the rapid and sensitive determination of trace amounts of an organophosphonate: 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) in aqueous solution. This method is based upon reactive pyrolysis-GC/MS in the presence of tetramethyl ammonium hydroxide (TMAH). Approximately 10 microL of the aqueous sample containing a trace amount of HEDP and 1 microL of 25% a methanol TMAH solution was placed in the sample cup. The cup was then dropped into the furnace which was at 350 degrees C. The heat initiated the hydrolysis of the organophosphonate followed by the methylation of the hydrolysates. Trimethylphosphate (TMP) was detected by GC/MS. The level of TMP is related to the level of the phosphonate, HEDP in the aqueous sample. Using an external standard calibration curve, it was possible to make a rapid estimation of mg/L levels of organophosphate.

Evaluation of the thermal desorption-GC/MS method for the determination of decabromodiphenyl ether (DeBDE) in order of a few hundred ppm contained in a certified standard polystyrene sample.

Thermal desorption (TD)-GC/MS, recently developed for the determination of DeBDE in a polystyrene (PS) sample to an order of a few %, was evaluated in detail by using a certified standard PS sample containing 317 ppm of DeBDE. Not only the accuracy and precision of the results, but also the linearity of the working calibration curve were discussed in terms of the catalytic decomposition of DeBDE induced by the degrading macro-radical of the matrix polymer.

Photosensitized hydrogen evolution from water using conjugated polymers wrapped in dendrimeric electrolytes.

High-efficiency light-driven hydrogen evolution from water was demonstrated by using poly(phenyleneethynylene) bearing negatively charged, [G3] poly(benzyl ether) dendrimeric side groups 3(L4) as photosensitizer. Three-dimensional wrapping of the conjugated backbone suppressed self-quenching of the photoexcited state, while methyl viologen (MV(2+)), a positively charged electron acceptor, was trapped on its negatively charged surface, to form a spatially separated donor-acceptor supramolecular complex. Studies with time-resolved fluorescence spectroscopy showed that the quenching rate constant (k(q) = 1.2 x 10(15) M(-1) s(-1)) is much greater than diffusion control rate constants. Upon excitation of 3(L4) in the presence of a mixture of MV(2+), triethanolamine (TEOA; sacrificial electron donor), and a colloidal PVA-Pt, hydrogen evolution took place with an overall efficiency of 13%, 1 order of magnitude better than precedent examples. Comparative studies with several reference sensitizers showed that spatial isolation of the conjugated backbone and its long-range pi-electronic conjugation, along with electrostatic interactions on the exterior surface, play important roles in achieving the efficient photosensitized water reduction.