Determination of gold fineness by laser induced breakdown spectroscopy with the simultaneous use of CW-CO2 and Q-SW Nd:YAG lasers

In this work, the gold fineness is precisely determined using the dual beam arrangement including simultaneous irradiation of CW-CO₂ and Q-SW Nd:YAG lasers. It was shown that the enhancement of the characteristic emission lines occurs at higher temperatures with minimal surface distortion of the target respect to that of single beam exposure. The accuracy of gold concentration was determined to be as low as 0.7% using calibration-free (CF) method.     

Voltammetric Behavior of p‐Nitrophenol and Its Trace Determination in Human Urine by Liquid Chromatography with a Dual Reductive Mode Electrochemical Detection System

The determination of trace p-nitrophenol (PNP) concentrations in human urine has been successfully achieved by high performance liquid chromatography dual electrode detection (LC-DED) in the reduction-reduction mode. Initial cyclic voltammetric studies were undertaken to investigate the electrochemical behavior of PNP at a glassy carbon electrode over a wide pH range; the redox processes giving rise to the signals have been deduced. Further, deductions regarding the behavior in the flow cells were made from hydrodynamic voltammetric data. PNP eluting from the analytical LC column is first reduced to p-hydroxylaminophenol, at the first generator electrochemical cell. This species then undergoes chemical oxidation to give a quinoneimine species which is then detected at the downstream detector electrode using an applied potential of −0.1 V. The optimum chromatographic mobile phase consisted of 40% acetonitrile, 60% water, containing 25 mM o-phosphoric acid, at a flow rate of 0.5 mL/min; this was used in conjunction with a Hypersil C₁₈ column. Hydrodynamic voltammetric studies were undertaken to investigate the dual electrode behavior of PNP, and an applied potential of −2.0 V at the generator cell and −0.10 V at the detector cell were found to be optimum. The response was found to be linear over the range 7.0 ng to 500 ng on column, with an associated R² value of 0.9981; the limit of detection was found to be 1.0 ng PNP on column. No interferences were seen for a number of common drugs or for the principal electrochemically active components of human urine or serum. The developed assay was successfully applied to the determination of trace concentrations of PNP in human urine samples, exhibiting coefficients of variation of 7.1% (n=7), with a mean recovery of 94.7% for urine fortified at 522 ng mL⁻¹.     

环境水样中镍的微型柱现场预富集流动注射火焰原子吸收测定

以负载8-羟基喹啉(Oxine)、二乙基二硫代氨基甲酸钠(DDTC)和吡咯啶二硫代氨基甲酸铵(APDC)3种螯合剂的活性炭(AC)为微型柱的吸附材料,采用微型柱现场采样(MFS)分析技术实现了连续现场富集环境水样中的痕量Ni,并在实验室中采用流动注射(FI)-火焰原子吸收(FAAS)联用技术对吸附柱中富集的Ni进行了测定。该方法用于环境水样中Ni的测定获得了满意的结果。10 mL水富集Ni的检出限(3δ)为2.62μg.L-1,相对标准偏差为1.02%。     

Removal of Disperse Dyes from Water Using Surfactant Treated Alumina

An alumina surface was modified by adsorption of an anionic surfactant, sodium dodecyl sulfate (SDS). Typical S‐shaped isotherm of surfactant on alumina was observed. The adsorption of Disperse Red‐11, Disperse Blue‐26 and Disperse Red‐156 on alumina and surfactant treated alumina has been investigated. The enhancement in adsorption of these disperse dyes on surfactant treated alumina is observed, which may be attributed to their solubilization in surfactant aggregates formed at the solid/liquid interface. The effect of pH on adsorption has been studied. The adsorption is greatly influenced by pH of the medium. The applicability of the Langmuir model and the Dual‐Mode sorption model (DSM) were tested for equilibrium data.     

双波长光度法配合物组成和稳定常数的测定

利用双波长光度法的选择性这一特点，消除体系中有关物种的干扰，直接测定配体的平衡浓度，基于此结合溶液中物种的分布系数，建立了测定配合物组成和稳定常数的方法，手续简便可靠，试用于Ｃｕ（Ⅱ）－５－Ｂｒ－ＰＡＤＡＰ体系获得了满意的结果。     

Simultaneous electrochemical detection of multiple tumor markers based on dual catalysis amplification of multi-functionalized onion-like mesoporous graphene sheets

In this work, a sandwich-type electrochemical immunosensor for simultaneous sensitive detection of prostate specific antigen (PSA) and free prostate specific antigen (fPSA) is fabricated. Gold nanoparticles (AuNPs) modified Prussian blue and nickel hexacyanoferrates nanoparticles were firstly prepared, respectively, and then decorated onion-like mesoporous graphene sheets (denoted as Au@PBNPs/O-GS and Au@NiNPs/O-GS) as distinguishable signal tags to label different detection antibodies. Subsequently, streptavidin and biotinylated alkaline phosphatase (bio-AP) were employed to block the possible remaining active sites. With the employment of the as prepared nanohybrids, the dual catalysis amplification can be achieved by catalysis of the ascorbic acid 2-phosphate to in situ produce AA in the presence of bio-AP, and then AA was further catalyzed by Au@PBNPs/O-GS and Au@NiNPs/O-GS nanohybrids, respectively, to obtain the higher signal responses. The experiment results show that the linear range of the proposed immunosensor for simultaneous determination of fPSA is from 0.02 to 10 ng mL⁻¹ with a detection limit of 6.7 pg mL⁻¹ and PSA is from 0.01 to 50 ng mL⁻¹ with a detection limit of 3.4 pg mL⁻¹ (S/N = 3). Importantly, the proposed method offers promise for rapid, simple and cost-effective analysis of biological samples.     

Determination of Nitidine Chloride in Toothpaste by Dual Gradient Two-Dimensional High-Performance Liquid Chromatography

Nitidine chloride in toothpaste was determined by two-dimensional high-performance liquid chromatography. One gradient pump was used to enrich and purify the sample. The analyte was passed into the analytical column by switching a valve following the removal of the sample matrix. The samples were extracted by ultrasonic extraction. A C₁₈ (2.1 mm × 100 mm, 5 µm) column was used in one dimension, and a second C₁₈ (4.6 mm × 250 mm, 5 µm) column was used in the other dimension. The mobile phase was 0.02 mol/L monobasic potassium phosphate and acetonitrile with double isocratic elution. The wavelength of the ultraviolet-visible detector was 328 nm. The linear range for nitidine chloride was between 0.01 and 2 mg/L, with a correlation coefficient greater than 0.9998. The limit of detection for nitidine chloride was 0.01 mg/kg. The mean recoveries were 88.7% to 91.0%, and the relative standard deviation was less than 2.81%. This method is simple, sensitive, and accurate for the determination of nitidine chloride in toothpaste.     

Dual‐templates molecularly imprinted monolithic columns for the evaluation of serotonin and histamine in CEC

To extend the application of molecularly imprinted polymers, the dual‐templates molecularly imprinted monolithic columns were developed in a capillary format. Two templates serotonin and histamine were simultaneously imprinted using two different functional monomers such as methacrylic acid (MAA) and methylenesuccinic acid (MSA) in a mixture of ethylene glycol dimethacrylate (EDMA) as a cross‐linker and AIBN as polymerization initiator dissolved in DMF as porogen. The resulting molecular imprinted polymers (MIPs) were characterized based on their performance in the CEC separation of two imprinted templates. The optimization parameters such as pH, ACN composition, and concentration of the eluent were varied to achieve best resolution and efficiency for CEC separation of templates with each MIP column. It was found that the MIP monolith column fabricated using MSA offered better resolution and separation efficiency compared to column fabricated with MAA. This work utilized the dual‐templates imprinting approach successfully and broadens the scope of multi‐templates imprinting capabilities in capillary format in CEC application.     

分子内电荷转移双重荧光体识别阴离子研究

设计合成阴离子受体是近年来超分子化学中一个颇为活跃的研究领域[1～ 7] .其中荧光法以其高灵敏度和高选择性等特点使发光受体的设计合成备受关注 [6 ,7] .分子内电荷转移 (Intramolecular charge transfer,ICT)原理已被成功地用于构筑阳离子荧光传感体系[8] ,但将其应用于阴离子识别的研究尚鲜见报道[9～ 12 ] .本文设计合成了 ICT荧光体对二甲氨Scheme 1　 The structures of anion receptors基苯甲酰肼 (DMABH,结构见 Scheme 1 ) ,研究了 DMABH与阴离子如 HSO- 4,Ac O- ,H2 PO- 4,Cl O- 4,NO- 3,Cl- 和 Br- 等结合后的光…