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The hexavalent chromium (Cr(VI)) ion adsorption properties were conferred to porous silica beads by introducing alkylamine chains through functionalization with an aminosilane coupling agent, [3-(2-aminoethylamino)propyl]triethoxysilane (AEAPTES), or with an epoxysilane coupling agent, (3-glycidyloxypropyl)triethoxysilane (GOPTES), and polyfunctional amine compounds or poly-ethylenimines (PEIs). The presence of amino groups on the silica beads was confirmed by XPS and the amount of amino groups increased to 0.270 mmol/g by increasing the AEAPTES concentration and/or reaction time. The adsorption capacity of the silica beads functionalized with AEAPTES was the maximum at the initial pH value of 3.0 and the initial adsorption rate increased with an increase in the temperature. The adsorption capacity increased with an increase in the amount of amino groups at pH 3.0 and 30 °C. The adsorption behavior obeyed the pseudo-second order kinetic model and was well expressed by the Langmuir isotherm. These results support that Cr(VI) ion adsorption is accomplished through the electrostatic interaction between protonated amino groups and HCrO4− ions. In addition, the adsorption capacity further increased to 0.192–0.320 mmol/g by treating the GOPTES-treated silica beads with triethylenetetramine, pentaethylenehexamine, or PEI. These empirical, equilibria, and kinetic aspects obtained in this study support that the porous silica-based adsorbents prepared in this study can be applied to the removal of Cr(VI) ions.

A polymeric adsorbent for removal of hexavalent chromium (Cr(VI)) ions was developed by the photografting of 2-(dimethylamino)ethyl methacrylate (DMAEMA) to a polyethylene (PE) mesh and subsequent quaternization with iodoalkanes of different alkyl chain lengths. The grafting of DMAEMA and subsequent quaternization were verified by the FT-IR and XPS measurements. The Cr(VI) ion adsorption capacity of the DMAEMA-grafted PE meshes had the maximum value at the grafted amount of 2.6 mmol/g in a 0.20 mM K2Cr2O7 solution at pH 3.0 and 30°C. The adsorption behaviour obeyed the pseudo-second order kinetic model and well expressed by Langmuir isotherm. These results suggest that the Cr(VI) ion adsorption occurs through the electrostatic interaction mainly between protonated dimethylamino groups and hydrochromate (HCrO4-) ions. The adsorption capacity of the quaternized PE-g-PDMAEMA meshes increased with an increase in the degree of quaternization and/or the alkyl chain length of the iodoalkanes used and the maximum adsorption ratio was obtained at the degree of quaternization of 54.2% for the iodoheptane-quaternized PE-g-PDMAEMA (PE-g-QC7PDMAEMA) mesh. This value was about 1.86 times higher than that of the PE-g-PDAMEMA mesh. Cr(VI) ions were successfully desorbed from the PE-g-PDMAEMA and PE-g-QC7PDMAEMA meshes in eluents such as NaOH, NaCl, and NH4Cl. In 0.50 M NaCl, 0.10 M NH4Cl, and 0.50 mM NaOH, the adsorption and desorption process was repeatedly performed without any considerable decrease and the desorption behaviour obeyed the pseudo-second order kinetic model. These results emphasise that the PE-g-PDMAEMA meshes and their quaternized products can be applied as an adsorbent for Cr(VI) ions.

A new polymeric adsorbent for Cr(VI) ions based on an expanded poly(tetrafluoroethylene) (ePTFE) film was prepared by the combined use of the pretreatment with oxygen plasma and photografting of 2-(dimethylamino)ethyl methacrylate (DMAEMA). The grafting of DMAEMA was characterized by XPS and FT-IR spectroscopic measurements. The adsorption behaviour of DMAEMA-grafted ePTFE (ePTFE-g-PDMAEMA) films was investigated as a function of the experimental parameters, such as the initial pH value, temperature, and grafted amount. The adsorption capacity and initial adsorption rate had the maximum values at the initial pH value of 3.0. On the other hand, the adsorption capacity became almost constant at temperatures higher than 30°C, although the adsorption rate increased over the temperature. The adsorption behaviour obeyed the pseudo-second-order kinetic model and well expressed by the Langmuir isotherm equation with higher correlation coefficients. These results indicate that the adsorption of Cr(VI) ions occurs through the electrostatic interaction between protonated dimethylamino groups on a grafted PDMAEMA chain and

We developed a flow injection analysis (FIA) method based on tris(2,2'-bipyridine)ruthenium(III) [Ru(bpy)3 3+] electrogenerated chemiluminescence for assessment of antioxidant property. The hydroxyl radical (∙OH) were generated by H2O photolysis using an ultraviolet/H2O photoreactor. The reactor comprised a polytetrafluoroethylene tube, a quartz container, and a low-pressure mercury lamp that predominantly emitted radiation at around 185 nm. When the hydroxyl radical and Ru(bpy)3 3+ were in contact, chemiluminescence was generated as background emission. The background emission decreased when antioxidant samples were injected to the system. The antioxidant property of the naturally occurring antioxidants tested are listed herein, starting with the highest: gallic acid>ascorbic acid>quercetin. Moreover, our method allowed a sample throughput of approximately 100 samples/h. The proposed high throughput method can be used to assess the antioxidant property of the naturally occurring antioxidants.

We developed a flow injection analysis (FIA) method based on tris(2,2'-bipyridine)ruthenium(III) [Ru(bpy)

We have developed a highly sensitive, simple method for the quantitative determination of miglitol in standard serum samples using column-switching ion-pair HPLC with tris(2,2'-bipyridine)ruthenium(II)-electrogenerated chemiluminescence detection. The serum samples were directly injected into a column-switching HPLC system with a Shim-pack MAYI-SCX precolumn to remove the serum matrix. Chromatographic separation of miglitol was achieved on a TSKgel ODS 100-V column using a mobile phase containing sodium 1-octanesulfonate as an ion-pair reagent. The detection and quantification limits of miglitol were 3 and 10 ng/mL, respectively. The calibration curve for miglitol in the serum samples showed good linearity (r(2)=0.9997) in the range of 10-2500 ng/mL. The recovery rate of miglitol from the serum samples was more than 94% as calculated from blank serum samples spiked with miglitol 50, 100, 500, 1000, and 2000 ng/mL. Therefore, this method can be applied to routine therapeutic monitoring of miglitol in serum samples.

Polyethylene (PE) plates grafted with a neutral monomer, 2-hydroxyethyl methacrylate (HEMA), and a cationic monomer, 2-(dimethylamino)ethyl methacrylate (DMAEMA), (PE-g-PHEMA)-g-PDMAEMA plates were prepared by the two-step photografting. The Cr(VI) ion adsorption behavior of the (PE-g-PHEMA)-g-PDMAEMA plates was investigated as a function of the amounts of grafted HEMA, amount of grafted DMAEMA, initial pH value, and temperature. The adsorption capacity of the DMAEMA-grafted PE (PE-g-PDMAEMA) and (PE-g-PHEMA)-g-PDMAEMA plates had the maximum value at the initial pH value of 3.0, independent of the temperature. The adsorption capacity of (PE-g-PHEMA)-g-PDMAEMA plates increased with the amount of grafted HEMA (G

To identify age-related proteins in small regions of mouse brain, we improved a proteomics approach, fluorogenic derivatization-liquid chromatography-tandem mass spectrometry (FD-LC-MS/MS), and applied the method to the differential proteome analysis of aging in cerebral cortex, hippocampus and brainstem. The method showed good accuracy with RSDs10% for between-day protein peak heights, and much better sensitivity for the detection of proteins compared to other proteomics approaches. The existence of 28 regionally specific age-related proteins in mouse brain was demonstrated. These results verified that the small brain regions could be the targets for proteome analysis by the FD-LC-MS/MS method.

A new polymeric adsorbent material based on polyethylene (PE) was prepared by photografting of 2-(dimethylamino)ethyl methacrylate (DMAEMA) as a positively chargeable monomer to a PE film. The effects of the experimental parameters, such as the pH value, temperature, and grafted amount on adsorption of chromium(VI) (Cr(VI)) ions were investigated for the DMAEMA-grafted PE (PE-g-PDAMEMA) films. The maximum adsorption capacity was obtained at the initial pH value of 3.0 for a PE-g-PDMAEMA film with 1.8 mmol/g and the maximum adsorption capacity obtained was higher than or compatible to those of many of the other polymeric adsorbents prepared for Cr(VI) ions. The adsorption kinetics obeyed the mechanism of the pseudo-second order kinetic model and adsorption of Cr(VI) ions on PE-g-PDMAEMA films was well expressed by the Langmuir isotherm model. A high Langmuir adsorption constant suggests that the adsorption of Cr(VI) ions occurs between protonated dimethylamino groups and HCrO4− ions mainly through the electrostatic interaction. Cr(VI) ions adsorbed were successfully desorbed from a PE-g-PDMAEMA film in solutions of NaCl, NH4Cl, NH4Cl containing NaOH, and NaOH and a PE-g-PDMAEMA film was regenerated and repeatedly used for adsorption of Cr(VI) ions without appreciable loss in the adsorption capacity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43360.

A highly sensitive and simple method using HPLC-fluorescence detection with 7-chloro-N-[2-(dimethylamino)ethyl]-2,1,3-benzoxadiazole-4-sulfonamide (DAABD-Cl) as a fluorogenic reagent demonstrated the existence of the low-molecular-weight thiols in the extract of Caenorhabditis elegans (C. elegans). The method includes derivatization of the thiols with DAABD-Cl at 40°C for 10 min in borate buffer (pH 9.0) containing TCEP, CHAPS and EDTA, separation of the derivatives on an ODS column and fluorometric determination of the derivatives at 510 ± 15 nm with excitation at 400 ± 15 nm. The identification of the thiols was made by HPLC-electrospray ionization mass spectrometry (LC-MS) following isolation of the derivatives using HPLC-fluorescence detection. Low-molecular-weight thiols were found to exist in the extract of C. elegans, such as cysteine, cysteinylglycine, γ-glutamylcysteine, reduced glutathione and two other unidentified thiol compounds, confirming the existence of the ‘glutathione cycle’ in C. elegans similar to the mammalian body. Copyright © 2007 John Wiley & Sons, Ltd.