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.

Sodium hexametaphosphate-treated halloysite based solid-phase extraction of biguanides from dietary supplements.

Raw halloysite was purified by using sodium hexametaphosphate and utilized as the solid-phase extraction sorbent for the determination of biguanides from dietary supplements. The purified halloysite was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The purified halloysite interacted with biguanides through hydrophilic interaction and ion exchange on account of its abundant hydroxyl groups and negative charge. Compared with traditional extraction methods based on hydrophobic interaction and/or ion exchange, the purified halloysite adsorbed more biguanides due to hydrophilicity and ion exchange, with a sample loading volume of up to 100 mL at least. Excellent reproducibility of halloysite purification was achieved, with within-batch (n = 3) and batch-to-batch (n = 3) relative standard deviations in the ranges of 1.5-4.2% and 5.6-8.8%, respectively. Coupled with reversed-phase liquid chromatography-tandem mass spectrometry, a low limit of detection of 0.3 µg kg-1 was obtained. The intra- and inter-day mean recoveries of the biguanides spiked at three levels in dietary supplements were within the ranges of 88.5-107.2% and 86.4-102.0%, respectively. The intra- and inter-day precisions were within the ranges of 1.5-6.4% and 5.4-9.9%, respectively. These results indicated that the developed method is efficient for the determination of trace biguanides in dietary supplements.

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.

Correction: Assessment of the toxicity and inflammatory effects of different-sized zinc oxide nanoparticles in 2D and 3D cell cultures.

[This corrects the article DOI: 10.1039/C6RA27334C.].

Antioxidant and Antiproliferative Activities of Cyanidin-3-O-Glucoside (C3G) Liposome in Caco-2 Cells Cultivated in 2D and 3D Cell Culture Models.

The aim of this study was to obtain adequate and detailed information about the antioxidant and antiproliferative activities of C3G and C3G liposomes in different cell culture models. The Caco-2 cells were cultured in 2D and 3D cell culture models, the H2 O2 was used to construct the cell damage model and then the cells treated with C3G and C3G liposomes. The antioxidant activity and antiproliferative activities of C3G liposomes on Caco-2 cells were investigated. We observed the morphology of cells and measured the cell viability, the activity of glutathione (GSH), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and the content of malondialdehyde (MDA) in Caco-2 cells treated with H2 O2 , C3G, and C3G liposomes. The results showed that the Caco-2 cells cultured in the 3D culture model formed a 3D structure and tight spheroids and showed the increase of cell activity in 3D cell culture model, compared with the 2D cell culture model. The C3G and C3G liposomes can enhance the activities of GSH, SOD, and T-AOC but decrease the MDA content after H2 O2 treatment, while the changes were different in 2D and 3D cells culture models. This study revealed that the results obtained from the 2D cell model may be inaccurate compared with the results obtained from the 3D cell model. PRACTICAL APPLICATION: The results of this study showed that the results obtained from the 2D cell model may be inaccurate compared with the results obtained from the 3D cell model. Our work provides a method for evaluating antioxidant activity of C3G liposomes in different cell models and provided certain theoretical basis for the follow-up research.

Enhanced Antibacterial and Food Simulant Activities of Silver Nanoparticles/Polypropylene Nanocomposite Films.

In this work, we synthesize dodecyl mercaptan-functionalized silver nanoparticles integrated with polypropylene nanocomposite (DM-AgNPs/PP) substrates by a simple in situ melt blending method. The formation and distribution of AgNPs are confirmed by UV-visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and thermogravimetric analysis. The existence of DM-AgNPs in PP film substrate enhances the thermal degradation and crystallization properties. Further, the antimicrobial activity of as-synthesized DM-AgNPs/PP film substrate is studied using Gram-negative ( Escherichia coli) and Gram-positive ( Staphylococcus aureus) bacteria as model microbes, which displayed significantly enhanced bacteriostatic activities under optimized composition and experimental conditions. Interestingly, PP substrate with 0.4% DM-AgNPs exhibits drastically improved antibacterial property via the release of oxygen reactive species and Ag ion diffusion processes; thus, the inhibition rates of E. coli and S. aureus are obtained as 100 and 84.6%, respectively, which is higher than the conventional AgNPs. Finally, we demonstrate the migration study of Ag ions from the DM-AgNPs/PP film using different food simulant solutions by inductively coupled plasma-mass spectrometry analysis and the dissolved Ag ion content is estimated, which is a key prospect for the toxicity analysis. The overall Ag ion migration value is estimated between 1.8 and 24.5 µg/cm2 and displayed a lowest limit of Ag ion migration as 0.36 µg/cm2. Our work highlights the development of high performance nanocomposites as promising antibacterial and food simulant materials for biomedical and industrial applications.

Antioxidant and Antimicrobial Effects of Catechin Liposomes on Chinese Dried Pork.

In this study, catechin (CT), catechin liposome (CTL), and α-tocopherol (TP) were added to Chinese dried pork to achieve a healthy lipid composition. Their effectiveness in prevention of lipid oxidation was determined by measuring the values of thiobarbituric acid-reactive substances and peroxides. The total viable count in samples was used to identify the antimicrobial activities of CT, CTL, and TP, and the pH values of the samples were determined. Chinese dried pork with antioxidants added at 600 mg/kg was subjected to sensory evaluation. Thiobarbituric acid-reactive substance values, peroxide values, and total viable counts indicated that CTL significantly enhanced the antioxidant and antibacterial effects of CT on Chinese dried pork, especially after storage at room temperature for 25 days. Compared with the two other antioxidants, CTL could better maintain the pH stability of Chinese dried pork at room temperature. Sensory evaluation revealed that the scores of CTL were better than those of CT and TP in terms of preserving the color, flavor, tenderness, and overall acceptability of Chinese dried pork. Use of CTL in Chinese dried pork had good antioxidant and antibacterial effects and maintained color, flavor, and tenderness at a relatively stable level, suggesting that CTL could be used as an antioxidant in Chinese dried pork to enhance oxidative stability and prolong shelf life.

[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.