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Gao R.,Nanjing Normal University | Gao R.,Nanjing Institute of Product Quality Inspection | Zhang N.,Nanjing Normal University
Atomic Spectroscopy | Year: 2015

A different analytical line pair is required when the Pd 340.45-nm line, as recommended by ISO regulation 11495:2008, is not available on an inductively coupled plasma optical emission spectrometer (ICP-OES) for the determination of Pd in palladium jewellery alloys. This work selected Pd 342.124 nm and Y 371.030 nm as the optimal analytical line pair from 21 spectral lines of palladium and 7 spectral lines of yttrium based on recoveries, relative standard deviations (RSD), spectral interferences, simultaneous detection principle of the analyte and the internal standard signals. The recoveries of the line pair were in the range of 101.6∼101.9% and the RSD was 0.2% (n=10). This method is complementary to the ISO 11495:2008 regulation. Source

Su X.-M.,Guangxi University for Nationalities | Su X.-M.,Nanjing Institute of Product Quality Inspection | Li X.-Y.,Guangxi University for Nationalities | Liu M.,Guangxi University for Nationalities | And 3 more authors.
Gongneng Cailiao/Journal of Functional Materials | Year: 2014

Fe3O4 magnetic nanoparticles were synthesized by the chemical co-precipitation method. With (3-aminopropyl)triethoxysilane (APTES) on the surface modification, Fe3O4@SiO2-NH2 nanoparticles were formed. Core-shell magnetic molecularly imprinted polymers (Fe3O4@MIPs) were prepared by using Rhodamine 6G as template molecule, acrylamide (AM) as functional monomer, trimethylolpropane trimethacrylate (TRIM) as cross-linking agent, and amino-modified Fe3O4 magnetic nanoparticles as the magnetic core. The Fe3O4@MIPs were characterized using a Fourier transform infrared spectrometer(FT-IR), field emission scanning electron microscope (FESEM), vibrating sample magnetometer(VSM), and thermogravimetric analysis (TGA). The Fe3O4@MIPs showed a highly improved imprinting capacity and significant selective; they could be used as solid-phase extraction material and applied to the safety detection of illegal add Rhodamine 6G in foods. ©, 2014, Journal of Functional Materials. All right reserved. Source

Gao R.-F.,Nanjing Normal University | Gao R.-F.,Nanjing Institute of Product Quality Inspection | Gao M.-C.,Nanjing Institute for Food and Drug Control | Ling R.,Nanjing Institute for Food and Drug Control | Zhang N.,Nanjing Normal University
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2016

The measurement uncertainty is a non-negative parameter associated with the result of a measurement that characterizes the dispersion of the quantity values that could reasonably be attributed to the measurand. In the present study measurement uncertainty is estimated using the GUM (ISO/IEC Guide 98: 1993 Guide to the expression of uncertainty in measurement) bottom-up approach. The steps were followed: specifying the measurand; identifying all the associated sources of uncertainty; quantifying the uncertainty components; combining the uncertainty components; determining the extended combined standard uncertainty; reviewing the estimates and reporting the measurement uncertainty. In this process, the major uncertainty components with greater impact were identified; try to eliminate or to reduce the impact of these components can improve measurement methods. Examples were the determination of aluminum in starch and bread crumbs by inductively coupled plasma-mass spectrometry (ICP-MS). The uncertainties of aluminum contents were from measurement repeatability, variability of calibration curve, standard stock solution, dilution, solution volume and sample weighing. The data indicated that the major contributions to the uncertainty budget originating from urel(cAl)1 (the relative standard uncertainty of aluminum content derived from linear least squares calibration), urel(cAl)3 (the relative standard uncertainty of aluminum content derived from the dilution of the standard stock solutions) and urel(rep) (the relative standard uncertainty derived from the repeatability). Based on the analysis of the main individual contributions of each uncertainty source to the total uncertainty value, several modifications were proposed. Firstly helium collision mode was replaced by no gas mode to improve the sensitivity of mass spectrometry. Secondly the number of measurements was increased. Thirdly let the mean of data points in the calibration closer the measurand. Finally the relative error smaller gauges were used. After these modifications, urel(cAl)1, urel(cAl)3 and urel(rep) were from (0.0358, 0.0132, 0.0085) down to (0.0060, 0.0105, 0.0033), respectively; the combined relative standard uncertainty of aluminum was from 0.039 down to 0.013; the expanded uncertainty from 1.8 down to 0.4 mg·kg-1 (coverage factor k=2). The improvement effect was significant. © 2016, Peking University Press. All right reserved. Source

Wang R.-H.,Nanjing Forestry University | Wang R.-H.,CAS Nanjing Institute of Soil Science | Zhu X.-F.,Nanjing Forestry University | Zhu X.-F.,Nanjing Institute of Product Quality Inspection | And 5 more authors.
Environmental Science and Pollution Research | Year: 2016

Batch experiments were conducted to investigate cadmium(II) (Cd(II)) adsorption by two variable-charge soils (an Oxisol and an Ultisol) as influenced by the presence of pectin. When pectin dosage was less than 30 g kg−1, the increase in Cd(II) adsorption with the increasing dose of pectin was greater than that when the pectin dosage was >30 g kg−1. Although both Langmuir and Freundlich equations fitted the adsorption isotherms of Cd(II) and electrostatic adsorption data of Cd(II) by the two soils well, the Langmuir equation showed a better fit. The increase in the maximum total adsorption of Cd(II) induced by pectin was almost equal in both the soils, whereas the increase in the maximum electrostatic adsorption of Cd(II) was greater in the Oxisol than in the Ultisol because the former contained greater amounts of free Fe/Al oxides than the latter, which, in turn, led to a greater increase in the negative charge on the Oxisol. Therefore, the presence of pectin induced the increase in Cd(II) adsorption by the variable-charge soils mainly through the electrostatic mechanism. Pectin increased the adsorption of Cd(II) by the variable-charge soils and thus decreased the activity and mobility of Cd(II) in these soils. © 2016 Springer-Verlag Berlin Heidelberg Source

Yue K.,Nanjing University of Technology | Cheng X.,Nanjing Institute of Product Quality Inspection | Xia J.,Nanjing University of Technology | Lu W.,Nanjing University of Technology | And 3 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2015

The mechanical performance of common wood plastic composites was poor and couldnot be used as structural member. Structural wood-plastic laminated timber was prepared with domestic fast-growing poplar wood veneer and thermoplastic plastic alloy by the flat-pressed method. The plastic alloy was composed with polyethylene and polypropylene film with the weight ratio of 1:1 and acting as adhesive in laminated timber. The hot pressing temperature, ranging from the melting temperature of plastic alloy measured by differential scanning calorimeter to the pyrolysis temperature of wood materials, could be determined preliminarily. Secondly the effects of the hot pressing temperature, the wood-plastic ratio and the concentration of maleic anhydride on the bonding strength of wood-plastic laminated timber were studied. Then the tests on the effects of the above 3 factors on the bending behavior of wood-plastic laminated timber were carried out. The results showed that, the interfacial damage mode of wood-plastic laminated timber with coupling agent under tension and shear forces was wood failure, while that of controlled specimens was interfacial delamination between wood and plastic. Compared with controlled specimens, the bonding strength of wood-plastic laminated timber pretreated with coupling agent was the highest, and increased by 16.7% at 180℃, wood-plastic ratio of 3/2 and maleic anhydride concentration of 4%. Wood-plastic laminated timber exhibited better mechanical properties with the flat pressing preparation method, and could be used as a structural wooden member. Bending strength was negatively correlated with modulus of elasticity for wood-plastic laminated timber. In the experiment, bending strength of wood-plastic laminated timber increased with the increasing of the wood density and the ratio of wood to plastic at the density of 0.6 and 0.8 g/cm3, while modulus of elasticity decreased, and the microstructure of wood kept integrated. Compared with the densities of 0.6 and 0.8 g/cm3, wood-plastic laminated timber was stronger at a density of 1.0 g/cm3. Bending strength decreased with the increasing of wood-plastic ratio at the density of 1.0 g/cm3. The resistance of wood-plastic laminated timber increased with the density and the wood-plastic ratio. There was much discontinuous crack at the direction of cross grain of wood veneer, so the structural integrity of wood decreased at a wood-plastic ratio of 3/3. The bending properties of wood-plastic laminated timber met the demands and reached the 100E level according to the national standard of China when the hot-pressing temperature was 190℃, the wood-plastic ratio was 3/2 and 3/3, the concentration of maleic anhydride was 4%, and the density was 0.8 g/cm3. The study may provide valuable information for the structural applications of wood-plastic laminated timber. © 2015, Chinese Society of Agricultural Engineering. All right reserved. Source

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