A novel sample preparation method based on polarity grouping for comprehensive determination of 315 pesticides and other contaminants in wolfberry by liquid chromatography-tandem mass spectrometry.

A novel sample preparation method based on polarity grouping was developed for the comprehensive determination of 315 undesirable low-weight organic pollutants ranging from polar to weakly polar in wolfberry. The method involves the swelling of the sample in ammonium acetate buffer, two-phase extraction, three-phase extraction, and dispersive solid phase extraction (D-SPE) with the assistance of low-temperature centrifugation and analysis by ultrahigh performance liquid chromatography coupled with electrospray ionization tandem mass (UHPLC-ESI-MS-MS) by using the multiple reaction monitoring mode. The recoveries of the analytes with wide range of polarity were satisfactory.

A generic and rapid analytical method for comprehensive determination of veterinary drugs and other contaminants in raw honey.

A generic, rapid, simple and low-cost analytical method for simultaneously screening and confirming 400 veterinary drugs and other contaminants in raw honey was developed. The method was based on one-step extraction and ultra-high performance liquid chromatography coupled with electrospray ionization and tandem mass spectrometry. A well-designed extraction method results in the complete precipitation of proteins and separation of analytes from carbohydrates and reduces the time and cost of analysis by covering polar to non-polar analytes.

A novel sample-preparation method for the generic and rapid determination of pesticides and mycotoxins in tea by ultra-performance liquid chromatography-tandem mass spectrometry.

A rapid, simple, and generic analytical method for the simultaneous determination of 140 undesirable low-weight pesticides and mycotoxins from different chemical classes in black tea was developed. The method involved swelling the sample in ammonium acetate buffer, extraction with acetonitrile-dimethyl sulfoxide, cleanup by dual dispersive solid-phase extraction (D-SPE) with the assistance of low-temperature centrifugation, and analysis by ultraperformance liquid chromatography coupled with electrospray ionization tandem mass spectrometry using multiple reaction monitoring mode. The interferences in the extract were eliminated by the combination of dual d-SPE using only C sorbent and anhydrous magnesium sulfate, which maintained the chromatographic column under the ideal condition for a long time and enabled satisfactory recoveries of hydrophobic and hydrophilic analytes simultaneously.

Generic and rapid determination of low molecular weight organic chemical contaminants in protein powder by using ultra-performance liquid chromatography-tandem mass spectrometry.

A rapid, simple, and generic analytical method that could simultaneously determine 291 undesirable low molecular weight chemical contaminants from different drug families in protein powder, such as veterinary drugs and pesticides, etc, had been developed. This method comprised the extraction with acetonitrile-dimethyl sulfoxide (DMSO), clean-up through dispersive solid phase extraction (D-SPE) and low temperature filtration, and analysis by ultra-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry at multiple-reaction monitoring mode. Acetonitrile-DMSO was more generic than acetonitrile or methanol for the extraction of large-scale organic chemical contaminants with different polarities in protein powder.

[Determination of copper, chromium and arsenic in wood and its products by high pressure digest-ICP-AES].

Sample preparation was studied, samples were sawn to be sawdust, screened by a 35 mesh sieve, dryed 4-5 h at 105 degrees C, and its homogeneity was tested by variance analysis. Sample pretreatment methods were investigated with wet decomposition, dry ashing, high pressure digest (including microwave-assisted closed digestion and steel liner PTFE vessel digestion). According to the comparative results, wet decomposition is fit for testing soluble copper, chromium and arsenic.

[The application of variable theoretical alpha influence coefficent to the matrix correction in Cr-Fe-Ni stainless steel].

X-ray fluorescence analysis software Spectra Plus was used to calculate theoretical alpha influence coefficents of other elements to Cr in seven stainless steel standard samples, theoretical alpha influence coefficients of elements, by which Cr signal was enhanced, varied largely with the change of elements content. Variable theoretical alpha influence coefficients, which varied with elements content, were used to correct the matrix effects in stainless steel, the secondary excitation of Cr by other elements were corrected, and Cr (0.3%-20.

[The influence of combined supplementation of glutamine and recombinant human growth hormone on the protein metabolism in severely burned patients].

Objective: To investigate the influence of combined supplementation of glutamine (Gln) and recombinant human growth hormone (rhGH) on the protein metabolism in severely burned patients.

Methods: Sixty severely burned patients were enrolled in the study and were randomly divided into control (C, n = 20) and Gln with rhGH (Gln + rhGH, n = 20) groups. The patients in C group received glycine as the placebo, while those in Gln group took Gln orally in dose of 0.