[Determination of perfluoroalkyl acids in lamb liver by high performance liquid chromatography- tandem mass spectrometry combined with dispersive solid phase extraction].

A method was developed for the determination of 19 perfluoroalkyl acids (PFAs) in lamb liver by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/ MS) combined with dispersive solid phase extraction. The sample was extracted with acidified acetonitrile, and then cleaned-up by a mixture of N-propylethylenediamine (PSA), C18 and graphitized carbon black (GCB) sorbents. The 19 PFAs were analyzed by HPLC-MS/MS with a C18 chromatographic column, adopting the multiple reaction monitoring (MRM) mode with negative electrospray ionization. The effects of the dosages of hydrochloric acid and the sorbents on the recoveries of the 19 PFAs were studied. For accurate quantitative analysis, the isotope internal standard method was used. The calibration curves were linear with the correlation coefficients over 0.998 in the range of 0.05-20 µg/kg for the 19 PFAs. The limits of detection were 0.004-0.111 µg/kg. The limits of quantification were 0.012-0.370 µg/kg. The mean recoveries of the 19 PFAs at spiked levels of 0.5, 1.0, 2.0 µg/kg were in the range from 80% to 128% with the relative standard deviations of 0.31%-11.1%. The developed method is rapid, simple, accurate. It is suitable for the determination of the 19 PFAs in large quantities of lamb liver samples.

Synthesis and characterization of quaternized beta-chitin.

Water-soluble 2'-O-hydroxypropyltrimethylammoniumchitin chloride (2'-O-HTACCt) was prepared directly from beta-chitin and 3-chloro-2-hydroxypropyltrimethylammonium chloride (CTA) in basic medium. The effect of alkali concentration, reaction temperature, reaction time, and dosage of CTA on yield and degree of substitution (DS) of 2'-O-HTACCt were studied. These quaternized chitin derivatives were characterized by FTIR and (1)H NMR spectroscopy, conductometric titration, and elemental analysis methods. Research results indicate that beta-chitin can react directly with CTA to produce a water-soluble 2'-O-HTACCt derivative with a high DS. The optimal preparation conditions were determined to be 35-40 wt% (aq NaOH), 40 degrees C (reaction temperature), 6h (reaction time), and 4 (molar ratio of CTA to beta-chitin unit).

[Harmful elements removal from Polygonum multiflorum by supercritical CO2 extraction].

OBJECTIVE: To remove harmful elements as copper, lead and arsenic from Polygonum multiflorum, a Chinese traditional medicine, by supercritical carbon dioxide extraction. METHODS: With sodium diethyldithiocarbamate (NaDDC) as a chelating agent and ethanol as a modifier, the effects of extraction style, time, pressure, temperature and amount of chelating agent on chelating extraction process were discussed. RESULTS: The condition was optimized as following: 28 MP as extraction pressure, 60 degrees C as extraction temperature, 1 h as static extraction time, 2 h as dynamic extraction time, m(herb) : m(NaDDC) = 5 : 1, m(herb) : m(ethanol) = 1 : 1. Under this condition, the extraction rate of Cu, Pb and As were up to 60% which achieved US FDA standard, while the physioloically active substance of 2,3,5,4'-tetrahydroxy-silbene-2-O-beta-D-glucoside was not extracted. CONCLUSION: The results show chelating extraction by supercritical CO2 can provide a non-destructive method to decrease the content of harmful elements from Chinese traditional medicines.