甲醇／丙烷在ZSM－5分子筛上偶合转化过程的研究

考察了甲醇／低碳烷烃在ＺＳＭ－５分子筛上偶合转化为芳烃和低碳烯烃的反应过程。对特定的催化体系，存在一最佳原料配比，使反应的热效应近似为零。偶合转化时甲醇完全转化，低碳烷烃的转化率低；不同催化剂上偶合转化产物分布差别极大，与ＨＺＳＭ－５相比，Ｇａ改性后可获得较高的芳烃和低碳烯烃收率。     

Comparison of copper labeling followed by liquid chromatography-inductively coupled plasma mass spectrometry and immunochemical assays for serum hepcidin-25 determination

Hepcidin-25 has been defined as the key biomarker in iron metabolism. This peptide binds to the iron transporter ferroportin to cause its degradation. Therefore, the need for specific, accurate and precise methods for the quantification of hepcidin-25 in biological fluids is dramatically increasing. In this regard, the use of rapid immunochemical methods that provide low limit of quantification is desired for routine clinical use. However, such fast methodologies should be first analytically evaluated and compared with alternative strategies to check for their advantages and limitations. Here we compare the use of a commercial immunochemical assay for hepcidin determination with a novel analytical approach based on Cu-labeling of the peptide followed by Cu determination using liquid chromatography (HPLC) and plasma mass spectrometry (ICP-MS). The figures of merit of both systems reveal similar analytical characteristics and both seem to be adequate for the determination of the peptide at biologically relevant concentrations in human serum samples. The analysis of a larger number of samples (n = 50) by both techniques showed a good agreement in the concentrations found. Such finding permits to address the hepcidin recovery in the sample preparation procedure necessary for the HPLC-ICP-MS analysis in human serum that turn out to be 76–85%. Additionally, limitations due to cross-reactivity issues of the ELISA method could be addressed in some of the samples by using LC-ICP-MS and were confirmed by LC-Electrospray-MS.     

Development and validation of HPLC coupled with triple quadrupole MS for the simultaneous determination of six phenolic acids,six flavonoids,and a lignan in Polygonum capitatum

Polygonum capitatum, a traditional Miao medicinal plant, has significant effects on the treatment of urinary system infections and pyelonephritis. However, no study about the comprehensive quality evaluation of P. capitatum has been reported. In this contribution, a rapid and validated method based on HPLC coupled with triple quadrupole MS was established for the simultaneous determination of six active flavonoids, six phenolic acids, and a lignan in extracts of P. capitatum. These compounds were separated within 10 min on a C₁₈ analytical column with gradient elution. All analyses were performed on an Agilent XDB C₁₈ column (2.1 × 100 mm, 3.5 μm) with a linear gradient elution of acetonitrile/water. The proposed method was applied to analyze 15 batches of samples with acceptable linearity (r², 0.9923–0.9992), precisions (RSD, 1.0–3.0%), repeatability (RSD, 2.0–3.2%), stability (RSD, 2.2–3.2%), and recovery (RSD, 2.1–3.6%) of the 13 compounds. These results demonstrated that this presented method was effective and reliable for the comprehensive quality evaluation of P. capitatum. Moreover, our study can provide chemical evidence to reveal the material basis of its therapeutic effects.     

The use of 1-phenyl-3-methyl-4-benzoyl-5-pyrazone as chemical modifier for low-temperature electrothermal vaporization for separation and determination of Cr(III) and Cr(VI) by ICP-MS

Based on thermal stability and volatility of 1-phenyl-3-methyl-4-benzoyl-5-pyrazone (PMBP) chelate, a novel method was described for the determination of Cr(III) and Cr(VI) by low-temperature electrothermal vaporization (LETV) combined with inductively coupled plasma mass spectrometry (ICP-MS). It was found that Cr(III) could be rapidly formed in a graphite furnace, and quantitatively vaporized into ICP at a relatively low temperature of 1000 °C with the use of PMBP as a chemical modifier, while Cr(VI) was retained in the graphite tube. Thus, the separation of Cr(III) and Cr(VI) could be realized. The main factors affecting the formation and vaporization of Cr(III)-PMBP chelate were investigated in detail. Under the optimized conditions, the detection limit of Cr(III) for this method was 0.031 ng mL⁻¹ and the relative standard deviation (RSD) for 1.0 ng mL⁻¹ Cr(III) was 5.3% (n = 9, v = 10 μL). The linear range of calibration curve spanned three orders of magnitude. The proposed method was applied to the determination of Cr(III) and Cr(VI) in water samples with satisfactory results.     

Sample preparation procedure for the determination of sulphur and trace metals in oil products by the ICP with a minitorch using emulsions

A quick sample preparation method was used for the determination of sulphur and trace metals in oil and oily products by the ICP with a minitorch. Stable aqueous emulsions of oils and oil products were made by using two kinds of emulsifiers (one with low sulphur content, the other sulfonated). Aqueous standard solutions can be used for the preparation of calibration solutions. The contents of S, Al, Cr, Cu, Fe, Mg, Ni and Pb in aqueous emulsions were determined and the results were in good agreement with the composition of oil standard solutions used for control analysis procedure.     

微型柱在线分离-ICP-MS法测定高纯氧化铕中的14个稀土杂质

研究了微型柱在线分离-电感耦合等离子质谱法（ICP-MS）测定高纯Eu2O3中痕量Tm的方法，研制了Cyanex272负载树脂微型分离柱，优化了分离Eu2O3基体的实验条件，在线分离测定时间为25min。建立了在线柱分离测定Tm，内标补偿法直接测定其余稀土杂质的高纯Eu2O3中14个稀土杂质的ICP-MS分析方法。方法检出限为0.01μg/g-0.15μg/g，加标回收率为91.5%-110%,相对标准偏差为1.7%-4.9%。可满足快速测定99.999%Eu2O3中14个稀土杂质的要求。     

ICP—AES法测定玩具材料中痕量砷,硒,锑

用电感耦合等离子体原子发射光谱法（ＩＣＰ－ＡＥＳ０测定了玩具材料中的痕量砷，硒和锑。方法简便快速，回收率为９７．５％－１０２．７％，相对标准偏差小于３％。     

鲨鱼软骨质量的聚类分析法

用电感耦合等离子体原子发射光谱法（ＩＣＰ－ＡＥＳ）测定了１８个鲨鱼软骨真品中１３个元素含量，对测定结果进行分析和变量聚类分析，抽提５个特征指标，并以谱系数聚类建立了鉴别鲨鱼软骨真伪的数学模式，用３个假冒产品和一个鲨鱼软骨胶囊对其进行检验，结果表明，用无机元素所建立的数学模式不仅能鉴别鲨鱼软骨的真伪，还能区分鲨鱼软骨的部分及不同部位的混合物。     

Preconcentration and atomic spectrometric determination of rare earth elements (REEs) in natural water samples by inductively coupled plasma atomic emission spectrometry

The usage of a variety of sorbents has been shown as promising matrix removal/preconcentration strategies for the determination of rare earth elements (REEs) in various natural water samples by inductively coupled plasma atomic emission spectrometry (ICP-AES). The sorption efficiency of various zeolites (clinoptilolite, mordenite, zeolite Y, zeolite Beta), ion-exchangers (Amberlite CG-120, Amberlite IR-120, Rexyn 101, Dowex 50W X18) and chelating resins (Muromac, Chelex 100, Amberlite IRC-718) towards REEs was investigated in terms of solution pH, shaking time and sorbent amount. The results have shown that most of the materials can take up REEs at a wide pH range. The experiments were continued with clinoptilolite, zeolite Y and Chelex 100 and it was demonstrated that all three materials displayed very fast kinetics for REE sorption (higher than 96% in 1 min). Desorption from the sorbents was realized with 2.0 M HNO₃ for clinoptilolite and 0.1 M HNO₃ for zeolite Y and Chelex 100. Only the lower concentration range (0.01-2.0 mg l⁻¹) of matrix-matched standards were used in quantitation although the calibration graphs were linear at least up to 10.0 mg l⁻¹ for all REEs studied. The limit of detection (3 s) without preconcentration was 0.1, 1.0, and 0.2 μg l⁻¹ for Eu, La, and Yb, respectively. The validity of the method with the selected sorbents was checked through spike recovery experiments.