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. The matrix-fortified standard calibration curves were compared for quantification. The results of linearity were satisfactory with linear regression coefficients (R) ranging from 0.9901 to 1.000. The limits of quantification ranged from 1 µg/kg to 10.0 µg/kg, indicating the compliance of products with legal tolerances. The average recoveries for spiked wolfberry were in the range of 69.3 %-145.2 % with RSD values of 0.2 %-28.6 %. The inter-day precision was in the range of 0.2 %-27.0 %. For over 90 % of the analytes, the recoveries were 70 %-120 % with RSD values below 20 %. The application of this method in routine monitoring programs would imply a drastic reduction of both effort and time.

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. Optimized pretreatment processes lead to no significant interference on analysis from complicated sample matrix. Competent linearity was found for all of target compounds with linear regression coefficients (R) higher than 0.99. Detection limits ranged from 0.05 µg/kg to 10 µg/kg. Average recovery rates spiked in raw honey and ranged from 57.3% to 139.8%, and associated relative standard deviation values ranged from 0.4% to 25.2% under selected conditions. The extraction sensitivity, linearity, recovery, and precision of the method were validated. The results clearly demonstrated the feasibility of using this approach in raw honey purchase. The application of this method, which improved efficiency and the coverage of residues, may considerably reduce effort and time in routine monitoring programs.

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 C18 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. Matrix-matched calibration curves were obtained for most target compounds with linear regression coefficients above 0.9900. The limits of quantification (LOQs) ranged within 0.5-10.0 µg/kg, which were usually sufficient to verify the compliance of products with legal tolerances. Satisfactory recoveries of 64.5%-138.1% were obtained in black ta samples with the relative standard deviation (RSD) values between 1.8 and 25.9%. The inter-day precision ranged within 2.2%-24.9%. For over 90% of the analytes, the recoveries were between 70% and 120%, with RSD values below 15.0%. The application of this method in routine monitoring programs can drastically reduce effort and time.

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. Most interferences in the extract were eliminated by the combination of D-SPE and low temperature filtration, which simultaneously provided satisfactory recoveries of both hydrophobic and hydrophilic analytes. In particular, besides the purification function, the sorbent of D-SPE also played an important role in grinding samples to improve extraction efficiency during homogenization. This streamlined approach allowed the processes of extraction and the main purification were carried out in one-step, and dramatically reduced sample preparation turnaround times and solvent consumption. For quantification, matrix-fortified calibration curves showed competent linearity for most of the target compounds with linear regression coefficients (r) higher than 0.9900, except for two analytes. The limits of quantification ranged from 0.1 µg/kg to 50 µg/kg, which was usually sufficient to verify the compliance of products with legal tolerances. The average recoveries for spiked protein powder ranged from 65.6% to 142.2% with associated RSD values between 0.5% and 28.5%. For over 90% of the analytes, the recoveries were between 70% and 120% with RSD values in the range of 1%-15%. Applying this method in routine monitoring programs would drastically reduce both effort and time.

[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. Dry ashing and high pressure digest are fit for testing total copper, chromium and arsenic, but arsenic is easy to lose in dry ashing. Acidity effect and matrix effect were discussed. A method was proposed for the determination of total copper, chromium and arsenic in wood and its products by high pressure digest-ICP-AES. The detection limit of copper, chromium and arsenic was 1.2, 0.2 and 7.1 mg x kg(-1), respectively, RSDs were in the range of 0.2%-1.5%, and recoveries were between 92% and 106%. Using this method, more reasonable results will be given for controlling toxic substances from wood and its products and their wastes. This method has been applied to practical sample analysis.

[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 0.5 g kg(-1) d(-1) during 1-14 postburn days (PBDs). For the patients in Gln + rhGH group rhGH was administered subcutaneously in dose of 0.2 U kg(-1) d(-1) in addition to glutamine in same dosage beginning on the 7 PBD for 7 days. The plasma Gln concentration in the 3 groups of patients was determined on the 1st, 7th and 14th PBD and the plasma albumin level was determined on 14th and 21st PBD. The wound healing rate of the patients within 30 PBSs and the total hospital stay days were recorded. RESULTS: The plasma Gln concentration in Gln + rhGH group of patients was evidently higher than that in C group after 7 PBD[(452.28 +/- 21.72) micromol/L vs(325.12 +/- 25.34) micromol/L, P < 0.05]. The plasma albumin level in Gln + rhGH group was obviously higher than that in C and Gln groups on the 21st PBD (P < 0.05). The wound healing rate in Gln + rhGH group was evidently higher than that in Gln and C groups on the 30th PBD (P < 0.05). The total hospital stay days in Gln + rhGH group were obviously less than that in C and Gln groups (P < 0.05 or 0.01). CONCLUSION: Combined administration of Gln and rhGH could be beneficial to the elevation of plasma Gln level in severely burned patients and the systemic protein synthesis was therefore enhanced and the wound healing rate was improved.

[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%-20.8%) in stainless steel and low alloy steel could be analysed in accordance with one calibration curve. The matrix effects in samples can be corrected by variable theoretical alpha influence coefficients, so the measurable content range of calibration curve was enlarged. The contents of fifteen elements Al, Si, P, S, Ti, Cr, Mn, Co, Ni, Cu, As, Mo, Sn, W and Pb in stainless steel were measured by X-ray fluorescence spectrometer, variable theoretical alpha influence coefficients were used to correct the matrix effects, and the analysis results are comparable to those obtained by wet chemical method.