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.

Rapid determination of decabromodiphenyl ether in polystyrene by thermal desorption-GC/MS.

A rapid determination of decabromodiphenyl ether (DeBDE) in polystyrene (PS) by thermal desorption (TD)-GC/MS was studied. The TD-GC/MS method using a pyrolysis-GC/MS system allowed the quick quantification of DeBDE in a waste TV back plate composing of a PS flame-retarded with polybrominated diphenyl ethers on the basis of the resulting chromatogram with a ca. 4% relative standard deviation without using any tedious sample pretreatment, such as solvent extraction.

Rapid and sensitive determination of morphine in street opium samples by thermal desorption gas chromatography using a microfurnace pyrolyzer.

Thermal desorption of the alkaloids in opium samples at 300 degrees C using a vertical microfurnace pyrolyzer was followed by their on-line gas chromatographic (GC) analysis on a large-bore glass capillary column. This method permitted rapid and sensitive determination of the content of the main alkaloid, morphine, in the small (ca. 100 microg) opium samples with a relative standard deviation within 4% for 5 runs. The observed morphine contents of about 12 to 15 w/w% in the given opium samples were in fairly good agreement with those estimated by a conventional GC-MS method.

Development of a novel solid-phase extraction element for thermal desorption gas chromatography analysis.

A novel solid-phase extraction element is developed for sorptive enrichment of dilute analytes from liquid samples with high extraction efficiencies due to its larger amounts of polydimethylsiloxane (PDMS) absorbent than the conventional syringe type of solid-phase microextraction (SPME). The extraction element is made of titanium (Ti) open tubular tube (30 mm x 1.2 mm i.d. x 1.6 mm o.d.) coated with a chemically bonded layer of PDMS (500 microm in thickness). The extraction element combined with thermal desorption-gas chromatography-mass spectrometry using a pyrolysis-gas chromatography-mass spectrometry system was used to extract and analyze a typical herbicide, bethrodine in water samples over a concentration range from 2.5 to 2.5 x 10(4) ng/l. Thus obtained calibration curve showed good linearity for the tested whole concentration range with regression coefficient of 0.992. Detection limit of 0.5 ng/l level was achieved and the reproducibility of the measurements for bethrodine at 10 ng/l level was found to be fairly good with relative standard deviation below 7.5%.

Direct analysis of lipids in single zooplankter individuals by matrix-assisted laser desorption/ionization mass spectrometry.

A highly sensitive method to analyze the intact lipids in a single zooplankter individual at the level of a few tenths of a microgram was developed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with a direct sampling technique. The sampling procedure involved (1) putting a zooplankter individual sample onto the MALDI sample plate, (2) cutting the sample into a few pieces by means of tweezers, (3) depositing aliquots of matrix and cationization reagent solutions on the zooplankter sample, and (4) irradiating with a N2 laser to cause MALDI. By using this technique, the mass spectra of the single zooplankter samples showed a series of ions generated from phospholipids with 34 or 36 carbons in the acyl groups and neutral lipids such as triglycerides and diacylglyceryl ethers with 50-54 carbons in their acyl and alkenyl groups. Accordingly, this method enabled us to estimate the relative quantity between "structured lipids" (phospholipids) and "storage lipids" (neutral lipids) in an individual zooplankter, which should give us a good clue to elucidate the roles of each class of lipids in its growth.

Highly sensitive determination of a polymeric hindered amine light stabilizer in polypropylene by reactive thermal desorption-gas chromatography using nitrogen-specific detection.

Highly sensitive and specific determination of trace amounts of a polymeric hindered amine light stabilizer (HALS) in polypropylene (PP) materials could be established by improving reactive thermal desorption-gas chromatography (RTD-GC) in the presence of an organic alkali, tetramethylammonium hydroxide. By using nitrogen-phosphorus detection, highly selective detection of the HALS-related components was attained. In addition, the use of a polar poly(ethylene glycol) separation column alleviated the adsorption of minor specific pyrolysis products. This modified RTD-GC method allowed the determination of the polymeric HALS (Mr 1900) in PP even for trace concentrations between 100 and 500 ppm, through observing selectively the characteristic products containing a tetramethylpiperidine moiety, which had been impossible to detect under the previous RTD-GC conditions using a non-polar separation column and conventional flame ionization detection.

Characterization of oligomeric polypropyleneglycol acrylate by GC, SFC and MALDI-TOF-MS.

Polypropyleneglycol acrylate (PGA), one of the typical acrylic oligomers manufactured industrially, was comprehensively characterized by gas chromatography (GC), supercritical fluid chromatography (SFC) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The homologous series of polypropyleneglycol diacrylate (DA), polypropyleneglycol monoacrylate (MA), and unreacted polypropyleneglycol (PG) were observed as Na adducts in the MALDI-MS spectra of the PGA samples. The relative intensities of these peaks reflect the distributions of the homologues, although their accurate quantification was generally difficult because of change in the ionization efficiency depending on the chemical structure and the molecular weight of the species. On the other hand, the DA and the MA homologues were observed in the chromatograms obtained by SFC in a temperature-programming mode, while the PG homologues were not detected under the given SFC conditions using UV detection. Here, the determination of the degree of polymerization of each component in the chromatograms was accomplished through SFC fractionation for the corresponding peaks, followed again by MALDI-TOF-MS measurement. Furthermore, most of the components in the PGA samples were almost completely separated in the resulting gas chromatograms, and their unequivocal assignments were made also using the retention data on the gas chromatograms of the SFC fractions. As for the quantitative analysis, the relative abundances among DA, MA and PG for lower degrees of polymerization can be easily calculated based on the observed gas chromatograms, whereas the distribution of DA and MA can be estimated from the observed SFC data even for the relatively higher molecular weight fractions, which are generally difficult to determine accurately by GC because of their lower volatility. These results demonstrated that even the complex PGA samples were able to be characterized in detail by using GC, SFC and MALDI-TOF-MS complementarily.