[Determination of five coumarins in toys by high performance liquid chromatography-tandem mass spectrometry].

A rapid analytical method for the determination of five coumarins (coumarin, 7-methoxycoumarin, dihydrocoumarin, 7-methyl coumarin and 7-ethoxy-4-methyl coumarin) in toys by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has been developed. After ultrasonic extraction in tetrahydrofuran, the samples were analyzed by HPLC-MS/MS in multi-reaction monitoring (MRM) mode. Acetonitrile and 0.1% acetic acid were used as the mobile phases with gradient elution. The linear ranges of calibration curves were 10 - 1 000 microg/L, and the limits of quantification (LOQ) (S/N > 10) were 2.0 microg/L for all the analytes, except that the LOQ for dihydrocoumarin was 5.0 microg/L. The recoveries of the five coumarins spiked in three types of samples were in the ranges of 93.2% - 105.8%, 97.3% - 103.2% and 96.8% - 102.9%, with the relative standard deviations in the ranges of 4.35% - 8.27%, 3.65% - 6.73% and 4.03% - 6.45%, respectively. The method was applied in the determination of 12 toy samples. The five analytes were found in 9 samples, and in some cases, the presence of quite high concentrations of these coumarins in the toys should be a matter of concern.

[Determination of 3 isothiazolinone preservatives in toys using liquid chromatography-tandem mass spectrometry].

A rapid analytical method for the determination of 3 isothiazolinone preservatives (2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one and 1,2-benzylisothiazolin-3-one) in toys using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. After ultrasonic extraction with water, the analytes in the sample were separated and analyzed by LC-MS/MS under the isocratic elution of methanol and water (15:85, v/v) and in selected-reaction monitoring (SRM) mode. The linear ranges of calibration curves for the 3 analytes were 2.0 - 1 000 microg/L. The limit of quantification was 0.04 mg/kg for all the 3 analytes, which was lower than that of the method recommended by the European Toy Safety Directive in EN71-11-2005. The recoveries of the spiked standards in the two toy samples were 95.9% - 105.2% and 94.7% - 102.8% with the relative standard deviation ranges from 3.04% to 4.96% and from 2.36% to 4.79%, respectively. The method was applied in the determination of 10 toy samples, and the results can meet the requirements of the European Toy Safety Directive in EN71-9-2005 for the determination of isothiazolinones in toys.

Infrared spectra of the sulfenic ester CH3SOCH3 and its photodissociation products in solid argon.

UV light irradiation of dimethyl sulfoxide (DMSO) in low temperature solid argon matrix produces sulfenic ester, CH 3SOCH 3, a high energy structural isomer of DMSO. The sulfenic ester molecule further dissociates to the CH 2O-CH 3SH complex under 266 nm laser irradiation. The CH 2S-CH 3OH complex is also formed upon UV light irradiation. The infrared spectra of the aforementioned species are assigned on the basis of isotopic substitutions ( (13)C and deuterium) as well as density functional frequency calculations.

Reaction of vinyl radical with oxygen: a matrix isolation infrared spectroscopic and theoretical study.

The reaction of vinyl radical with molecular oxygen in solid argon has been studied using matrix isolation infrared absorption spectroscopy. The vinyl radical was produced through high frequency discharge of ethylene. The vinyl radical reacted with oxygen spontaneously on annealing to form the vinylperoxy radical C(2)H(3)OO with the O-O bond in a trans position relative to the C-C bond, which is characterized by O-O stretching and out-of-plane CH(2) bending vibrations at 1140.7 and 875.5 cm(-1). The vinylperoxy radical underwent visible photon-induced dissociation to the CH(2)OH(CO) complex or CH(2)OH+CO, which has never been considered in previous studies. The CH(2)OH(CO) product was predicted to be more thermodynamically accessible than the previously reported major HCO+H(2)CO channel, and is most likely produced by hydrogen atom transfer from the first-formed H(2)CO-HCO pair in solid argon.

Infrared spectra of phenyl nitrite and phenoxyl radical-nitric oxide complex in solid argon.

Infrared spectra and frequency assignment of two isomers of nitrobenzene, namely the phenyl nitrite C6H(5-)ONO molecule and the phenoxyl radical-nitric oxide complex C6H5O-NO, in solid argon are presented. The phenoxyl radical-nitric oxide complex was produced through UV light irradiation of nitrobenzene in low-temperature solid argon matrix. The complex rearranged to the more stable phenyl nitrite molecule on sample annealing. The aforementioned species were identified on the basis of isotopic IR studies with C6H(5-)(15)NO2 and C6D5NO2, as well as density functional theory calculations.

Infrared spectra of the OH+ and H2O+ cations solvated in solid argon.

Infrared spectra of various OH+ and H2O+ isotopomers solvated in solid argon are presented. The OH+ and H2O+ cations were produced by co-deposition of H2O/Ar mixture with high-frequency discharged Ar at 4 K. Detailed isotopic substitution studies confirm the assignments of absorptions at 3054.9 and 3040.0 cm(-1) to the antisymmetric and symmetric H-O-H stretching vibrations of H2O+ and 2979.6 cm(-1) to the O-H stretching vibration of OH+. The frequencies of H2O+ solvated in solid argon are red-shifted, whereas the frequency of OH+ is blue-shifted with respect to the gas-phase fundamentals. On the basis of previous gas-phase studies and quantum chemical calculations, the OH+ and H2O+ cations solvated in solid argon may be regarded as the OH+-Ar5 and H2O+-Ar4 complexes isolated in the argon matrix.