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Ensemble Partial Least Squares Algorithm Based on Variable Clustering for Quantitative Infrared Spectrometric Analysis

Yiming BI ; Guohai CHU ; Jizhong WU ; Kailong YUAN ; Jian WU ; Fu LIAO ; Jun XIA ; Guangxin ZHANG ; Guojun ZHOU

Chinese Journal of Analytical Chemistry.2015;(7):1086-1091. doi:10.11895/j.issn.0253-3820.150205

Due to the ability of overcoming both the dimensionality and the collinear problems of the spectral data, partial least squares ( PLS ) is in ever increasingly used for quantitative spectrometric analysis, especially for near-infrared spectrum, mid-infrared spectrum and Raman spectrum. In this work, an improved PLS algorithm is proposed for efficient information extraction and noise reduction. The spectral variables are clustering to several subsets, and several sub-models are built for each subset. Then, the sub-models are re-weighted and ensemble to the final model. Experiments on two near-infrared datasets ( octane number prediction in gasoline and nicotine prediction in tobacco leafs ) demonstrate that the new method provides superior prediction performance and outperformed the conventional PLS algorithm, and the root mean square error of prediction ( RMSEP) is reduced by 32% and 22%, respectively.

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Redox-Responsive Vesicles Prepared from Supramolecular 2-Hydroxypropyl-β-Cyclodextrin and Ferrocene Derivative for Drug Delivery

Xueni LI ; Longzhen ZHENG ; Yimin WANG ; Leyan XIONG ; Yan LOU ; Ting XIAO

Chinese Journal of Analytical Chemistry.2015;(7):1080-1085. doi:10.11895/j.issn.0253-3820.150258

A novel hydrophobic ferrocene polymer ( P-Fc) was synthesized successfully. Taken the advantage of 2-hydroxypropyl-β-cyclodextrin ( HP-β-CD ) with hydrophilic outside and hydrophobic inside, P-Fc was successfully enveloped in the cavity of HP-β-CD to form macromolecular vesicle by a self-assembly process. The structure and morphology of the macromolecular vesicle was characterized by FTIR, 1HNMR, SEM and CV. Rhodamine 6G (R6G) and doxorubicin hydrochloride (DOX) was used as target drugs and loaded in the vesicles successfully. After added the oxidant, ferrocene was oxidized to dicyclopentadienyl iron, which destroyed the vesicles successfully. The rapid directional release of the drugs was realized. The maximum loading values of R6G and DOX were 6. 89 and 39. 06 μg/mg, respectively. The release rates were 73. 7%and 88. 2%, respectively. It would increase the utilization level of the drugs and enhance their efficiency.

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Determination of Four Aflatoxins by Pressurized Capillary Electrochromatography-Laser Induced Fluorescence Detection

Qingyun WAN ; Xin RU ; Xiaoxi WANG ; Yan WANG ; Chao YAN

Chinese Journal of Analytical Chemistry.2015;(7):1063-1068. doi:10.11895/j.issn.0253-3820.150050

A rapid, reliable and sensitive pressurized capillary electrochromatography-Laser induced fluorescence ( pCEC/LIF ) method with trifluoroacetic acid ( TFA ) pre-column derivation for simultaneous determination of four aflatoxin ( AFB1 , AFB2 , AFG1 , AFG2 ) was developed. This method included separation on a capillary column packed with 1. 8μm C18 particles using 0. 05% FA aqueous solution/methanol (55:45, V/V) as mobile phase at a pump flow rate of 0. 05 mL/min when the split ratio was 1:300. Under the optimum conditions including running voltage of 15 kV, excitation wavelength of 375 nm and emission wavelength of 450 nm, the baseline separation of four aflatoxins was achieved within 10 minutes. The limits of detection (LODs) were 0. 02, 0. 016, 0. 008 and 0. 01 μg/L for AFG1, AFB1, AFG2, AFB2(S/N=3), respectively. The linear detection ranges of AFG1 , AFB1 , AFG2 , AFB2 were 0. 1-10, 0. 1-10, 0. 1-3 and 0. 1-3 μg/L with correlation coefficients (R2) of 0. 9999, 1. 0000, 0. 9995 and 0. 9997, respectively. The established method was applied to analyze the peanut butter, and the recoveries of standard addition experiment were between 90 . 0% and 112 . 0% for all analytes ( RSDs=0 . 5%-1 . 9%) .

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Analysis of Small Molecule Compounds by Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry with ZnO, CuO and NiO Nanoparticles as Matrix

Mengrui YANG ; Min WANG ; Xiaoyan TANG ; Jian ZHOU ; Xuefei MAO

Chinese Journal of Analytical Chemistry.2015;(7):1058-1062. doi:10.11895/j.issn.0253-3820.150191

Transition metal oxide ZnO nanoparticles as inorganic matrix was adopted in the matrix assisted laser desorption ionization time-of-flight mass spectrometry ( MALDI-TOF-MS ) analysis of small molecule compounds including sugars and stearic acid and its performances were investigated. In addition, the feasibility of metal ion selective ionization of L-arginine by using NiO and CuO nanoparticles as matrix directly was explored initially. In the experiment, the analyte and nanoparticle suspension were mixed on the sample plate. The crystal of analyte and matrix was excited by 337 nm laser after the solvent was evaporated, and then detected under reflection mode of TOF-MS. The results indicated that ZnO nanoparticles with high UV absorption could eliminate the interference of conventional matrix, simplify the mass spectra, and enhance the peak intensity of stearic acid under negative mode. Moreover, Cu+ ion selective ionization of L-arginine was achieved in comparison of CuO and NiO as matrix for MALDI-TOF-MS analysis of L-arginine.

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Determination of Bifenthrin in Tea by Ultra Performance Convergence Chromatography and Gas Chromatography-Mass Spectrometry

Liting WANG ; Bo WANG ; Wei ZHOU ; Qianqian LIU ; Shengxin YANG ; Yaheng ZHANG

Chinese Journal of Analytical Chemistry.2015;(7):1047-1052. doi:10.11895/j.issn.0253-3820.150096

A method was developed for the determination of bifenthrin in tea by ultra performance convergence chromatography ( UPC2 ) . The samples were extracted with petroleum ether and cleaned up with Waters Sep-Pak:Carbon NH2 , and then detected by UPC2 . The mobile phase was the mixture of supercritical CO2 and acetonitrile at a flow rate of 1. 5 mL/min. The separation was conducted on a column of ACQUITY UPC2 TM BEH (100 mmí3. 0 mm,1. 7 μm). The UV detector was set at a wavelength of 220 nm. The detection limit was 20 μg/L. The linear range of bifenthrin was 0. 32-10. 30 mg/L. The recoveries ranged from 88. 7% to 98. 2%. The relative standard deviations (RSD) were from 1. 4% to 2. 8%. The result showed that the UPC2 was more efficient, rapid and low-cost than GC-MS. The method can meet the testing requirements of bifenthrin in tea. The efficacy of UPC2 on testing the concentration of bifenthrin in tea was compared with GC-MS based on National Proficiency Testing and the results were satisfactory.

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Determination of Organophosphate Esters in Human Serum Using Gel Permeation Chromatograph and Solid Phase Extraction Coupled with GC-MS

Peng LI ; Qiuxu LI ; Yulong MA ; Jun JIN ; Ying WANG ; Yang TIAN

Chinese Journal of Analytical Chemistry.2015;(7):1033-1039. doi:10.11895/j.issn.0253-3820.150085

A gel permeation chromatography ( GPC ) coupled with solid phase extraction and gas chromatography-mass spectrometric ( GPC-SPE-GC/MS ) method was developed to analyze seven kinds of organophosphate esters ( OPEs ) , including tri-n-butylphosphate, tri ( 2-chloroethyl ) phosphate, triphenyl phosphate, tris ( 2-butoxyethyl ) phosphate, tri-o-tolylphosphate, tri-m-tolylphosphate, and tri-p-tolylphosphate) in human serum. The recoveries of cleanup methods between GPC-silica/alumina column and H2 SO4-silica/sulfuric acid gel column were compared. The purification method with the GPC-silica/alumina column didn’t destroy the structure of organophosphate esters ( OPEs ) and could effectively remove some protein and lipid matrix influence in serum. The developed method was verified using the spiked blank and the spiked serum, the good recoveries and reproducibilities were achieved. The recoveries of all of OPEs in spiked blank (n=3) were all more than 75%. The recoveries of d12-TCEP and d15-TPhP in human serum samples (n=9) were 86. 3%±21. 6% and 103. 1%±16. 5%, respectively. In human serum samples (n=9), the detection ratios for TnBP, TCEP, TPhP, TBEP and m-TTP were more than 90% in all of the serum samples, p-TTP was only 30%, o-TTP was not detectable. The concentrations of TnBP, TCEP, TPhP, TBEP and m-TTP in serum were 3. 4-46. 5 ng/g lipid, 248. 6-958. 2 ng/g lipid, n. d. -4. 2 ng/g lipid, n. d. -49. 9 ng/g lipid and n. d.-23. 1 ng/g lipid, respectively.

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Indirect Competitive Chemiluminescent Enzyme Immunoassay Method for Determination of Dimethyl Phthalate in Soy Sauce and Liquor

Bin ZHU ; Fan ZHU ; Zhenlin XU ; Jinyi YANG ; Chunhong LIU ; Yuanming SUN ; Hong WANG ; Hongtao LEI ; Yudong SHEN

Chinese Journal of Analytical Chemistry.2015;(7):1027-1032. doi:10.11895/j.issn.0253-3820.150153

4-Amino dimethyl phthalate as the hapten was coupled to carrier protein and then used to immunize New Zealand rabbits. Polyclonal antibody which showed specific binding to dimethyl phthalate ( DMP) was thus obtained, and on the basis of this, an indirect competitive chemiluminescent enzyme-linked immunoassay ( icCLEIA ) was developed. The experimental parameters of icCLEIA were optimized as follows: the concentration of coating antigen was 50 μg/L, the primary antibody concentration was 92. 5 μg/L, the secondary antibody concentration was 1μg/mL, distilled water (pH 6. 0) was used as diluent solution and the competitive reaction time was 40 min. Under the optimal conditions, the icCLEIA exhibited a linear working range from 0. 74μg/L to 30. 32μg/L with the limit of detection of 0. 29μg/L. The cross-reactivity of thirteen structural analogues was lower than 5%. The recovery of DMP from spiked liquor and soy sauce samples ranged from 80 . 2% to 116 . 0% and the average RSD was less than 3 . 6%. The detection results of the spiked liquor and soy sauce samples were consistent with those by standard gas chromatography-mass spectrometry method. The developed icCLEIA method exhibited a practical potential for detecting DMP residue in food samples.

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Preparation and Application of Molecular Imprinting Polymer Based Zero Current Potential Sensor for Benzidine

Mingming MA ; Chenglong LIU ; Xinke SU ; Fengqiu AN ; Wei ZHANG

Chinese Journal of Analytical Chemistry.2015;(7):1021-1026. doi:10.11895/j.issn.0253-3820.150052

The effects of polymerization conditions including scan potential range, scan cycles, the concentration ratio of template molecules to functional monomer, pH of the buffer, and washing time for removing the template molecule from the imprinted polymer on the difference of zero current potential of benzidine ( BZ) interaction with BZ-MIP were investigated. The optimum preparations were obtained. The imprinted capacity of benzidine, 4-chloroaniline, and 4-aminobiphenyl and carmine was calculated as 0. 632, 0. 1123, 0. 1123, 0. 0847 and 0. 0725, respectively. This indicated that BZ-MIP had good specific recognition and selectivity to benzidine, and other substances did not interfere with the binding of BZ-MIP with BZ. The zero current potential variation was linear with the lorgarithm of BZ concentration in the range of 4í10-8-1í10-5 mol/Lwith detection limitation of 1. 89í10-8 mol/L. The sensor was used to detect BZ in waste water sample with recoveries of 95 . 7%-104 . 2%.

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Determination of Chlorinated Anilines Residues in Soil by Gas Chromatography-Triple Quadrupole Mass Spectrometry Coupled with Solid Phase Microextraction

Ye CHEN ; Xiuyan XU ; Chao WANG ; Yibing LV

Chinese Journal of Analytical Chemistry.2015;(7):1009-1015. doi:10.11895/j.issn.0253-3820.150010

A gas chromatography-triple quadrupole mass spectrometry coupled with solid phase microextraction method ( SPME-GC/QQQ) was developed for the determination of chlorinated anilines ( CAs) residues in soil. The multi-reaction monitoring ( MRM ) parameters were optimized. The SPME conditions such as amount of soil sample, volume of added water, extraction temperature and absorption time were investigated. Optimum SPME conditions including 8 g of soil sample, 4 mL of water, 80℃ of extraction temperature and 40 min of absorption time were employed in the experiment. Method detection limits were within the range of 1-10 pg/g, while linearities were within the range of 5-1000 pg/g. Under the optimized conditions, the soil samples spiked with 200 pg/g targets were determined with recoveries of 96. 8%-144. 2%and relative standard deviations of 13 . 4%-27 . 8% ( n=5 ) . The proposed method combines simplicity and rapidity of SPME and high selectivity of MRM. It is especially suitable for the quick screening and determination of trace amounts of chlorinated anilines residues in soil.

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A Microfluidic Chip with Titanium Dioxide Membrane Enhanced Pseudo Valve Used for the Two-Dimensional Electrophoresis

Jianjia SU ; Hong CHEN

Chinese Journal of Analytical Chemistry.2015;(7):989-993. doi:10.11895/j.issn.0253-3820.150007

Two-dimensional electrophoresis performed on a microfluidic chip could reduce the consumption of sample and reagents, realizing high-throughput analysis in a very short time. During the isoelectric focusing ( IEF) separation, the buffer for the two different separation methods should be kept from being mixed. After the IEF, the protein was transferred from the IEF channel into the second dimension channels. Based on the pseudo valve structure, this paper reported a method to deposit a titanium dioxide membrane at the interface of two dimensional channels, which enhanced the performance of the pseudo valve. The IEF electrophoresis and SDS-polyacrylamide gel electrophoresis ( SDS-PAGE ) procedures were characterized respectively. The total separation took 10-15 min, and the protein's migration rate was linear with the migration time, and inversely proportional to the logarithm of protein molecular weight. Based on the above results, the differential two-dimensional electrophoresis was performed to test the deviation between different measurements.

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