巯基棉分离吸附溶出伏安法测定茶叶及茶汤中痕量砷

本文研究了巯基棉纤维（ＳＣＦ）对Ａｓ（Ⅲ）和Ａｓ（Ⅴ）的吸附性能，建立了ＳＣＦ分离Ａｓ（Ⅲ）和Ａｓ（Ⅴ）吸附溶出伏安法测定生物样品中痕量砷的方法。结果表明：在１ｍｏｌ／Ｌ盐酸介质中，ＳＣＦ可定量吸附Ａｓ（Ⅲ），Ａｓ（Ⅴ）不被吸附；用ＫＩ－（ＮＨ２）２ＣＳ预先还原Ａｓ（Ⅴ），通过ＳＣＦ分离，可消除干扰离子对测定砷的影响。方法用于测定桃叶、煤飞灰及番茄叶标样中的砷，其结果与标准值相符；应用此法还测定了几种茶叶及茶汤中的痕量砷和不同价态的砷，结果令人满意。     

氧化态Co／γ—Al2O3催化剂的结构与反应性能研究：Ⅱ.钴物种微观结？…

采用Ｘ－射线吸收近边结构（ＸＡＮＥＳ）和扩展Ｘ－射线吸收精细结构（ＥＸＡＦＳ）技术,对用不同原料盐和不同焙烧温度制得的Ｃｏ／γ－Ａｌ２Ｏ３催化剂中钴的微观结构进行了详细的表征。ＸＡＮＥＳ结果表明,以硝酸盐为原料盐于５００℃焙烧的样品Ｃｏ（Ｎ）－５００,其Ｃｏ－Ｋ边的近边结构与标样Ｃｏ３Ｏ４相似,而其它样品的近边结构则与标样ＣｏＡｌ２Ｏ４相似,随焙烧温度提高,在吸收边前的弱吸收峰（ｌｓ→３ｄ）逐渐增     

聚丙烯酰胺存在下Mohr法直接滴定碘、银等离子和硫氰酸根

1引言　　　　经典莫尔法对于　０．０１　ｍｏｌ／Ｌ的Ｃｌ－滴定误差达十０．６％需要进行指示剂的空白校正．且因　Ａｇｌ、ＡｇＳＣＮ沉淀强烈吸附Ｉ－和ＳＣＮ－、Ａｇ２ＣｒＯ４。沉淀凝聚后再转化成ＡｇＣｌ极慢，故不适于直接滴定Ｉ－、ＳＣＮ－、Ａｇ－。作者以聚丙烯酰胺（ＰＡＭ）化学修饰ＡｇＸ（ｘ－＝Ｉ－、ＳＣＮ－、Ｂｒ－、Ｃｌ－）及Ａｇ２ＣｒＯ４沉淀的结构，减小Ａｇｘ对Ｘ－的吸附与促进Ａｇ２ＣｒＯ４的转化，用莫尔法直接测定Ｉ－、ＳＣＮ－、Ａｇ＋及不需空白校正能准确滴定　０．０１　ｍｏｌ／ＬＣｌ－未见报道…     

STUDIES ON SYNTHESIS AND PROPERTIES OF BIS（β－ALKOXYCARBONYALKYL）TIN POLYTHIOETHERS

ＳＴＵＤＩＥＳＯＮＳＹＮＴＨＥＳＩＳＡＮＤＰＲＯＰＥＲＴＩＥＳＯＦＢＩＳ（β－ＡＬＫＯＸＹＣＡＲＢＯＮＹＡＬＫＹＬ）ＴＩＮＰＯＬＹＴＨＩＯＥＴＨＥＲＳＣｈｅＲｏｎｇｒｕｉ（ＩｎｓｔｉｔｕｔｅｏｆｔｈｅＰｏｌｙｍｅｒＣｈｅｍｉｓｔｒｙ，ＮａｎｋａｉＵｎ...     

煤焦油沥青基纤维状活性炭的吸附性能

煤焦油沥青基炭纤维（ＣＰＣＦ）价格低廉含炭量高、易于活化,是制备纤维状活性炭（ＣＰＡＣＦ）的优良原料。本文讨论了ＣＰＣＦ的抗拉强度和活化条件对ＣＰＡＣＦ比表面积的影响。并同石油系沥青基炭纤维（ＰＰＣＦ）进行了比较。考察了不同比表面积的ＣＰＡＣＦ、ＰＰＡＣＦ和商品用颗粒活性炭（ＡＣ）对０．１ｍｏｌ／Ｌ碘溶液、０．００５ｍｏｌ／Ｌ亚早兰溶液和２９３Ｋ下三氯甲烷饱和蒸汽的吸附性能,及以上三样品在２９３Ｋ     

ASYMMETRIC MICHAEL－TYPE ALKYLATION OF CHIRAL IMINES DIASTEREOSELECTIVE SYNTHESIS OF（＋）－α－CYPERONE AND （－）－10－EPI－α－CYPERONE

ＡＳＹＭＭＥＴＲＩＣ　ＭＩＣＨＡＥＬ－ＴＹＰＥ　ＡＬＫＹＬＡＴＩＯＮ　ＯＦ　ＣＨＩＲＡＬ　ＩＭＩＮＥＳ　ＤＩＡＳＴＥＲＥＯＳＥＬＥＣＴＩＶＥ　ＳＹＮＴＨＥＳＩＳ　ＯＦ（＋）－α－ＣＹＰＥＲＯＮＥ　ＡＮＤ　（－）－１０－ＥＰＩ－α－ＣＹＰＥＲＯＮＥＡＳ...     

碘化物-结晶紫-聚乙烯醇体系分光光度法测定自来水中痕量二氧化氯

在稀磷酸介质中，二氧化氯（ＣｌＯ２）氧化Ｉ离子形成 Ｉ３配阴离子，Ｉ３进一步与结晶紫（ＣＶ）阳离子形成离子缔合物［ＣＶ］［Ｉ３」。在聚乙烯醇存在下，该离子缔合物最大吸收波长λｍａｘ位于５５２ ｎｍ处，摩尔吸光系数ε＝２５ × １０５Ｌ·ｍｏｌ－１·ｃｍ－１，对 ＣｌＯ２的检出限为 ０．６ μｇ／Ｌ，线性范围是 ０．６～２８０μｇ／Ｌ。加入适量 ＫＦ溶液可消除自来水中Ｆｅ（Ⅲ）的干扰。方法对μｇ／Ｌ级ＣｌＯ２ 的测定有较好的选择性，可成功地用于自来水样品分析。     

CRINISINE，A NEW ALKALOID FROM CRINUM ASIATICUM L．VAR．SINICUM （ROXB．EX HERB）BAKER

ＣＲＩＮＩＳＩＮＥ，ＡＮＥＷＡＬＫＡＬＯＩＤＦＲＯＭＣＲＩＮＵＭＡＳＩＡＴＩＣＵＭＬ．ＶＡＲ．ＳＩＮＩＣＵＭ（ＲＯＸＢ．ＥＸＨＥＲＢ）ＢＡＫＥＲ￥ＲｅｎＪｉｕＴＡＮＧ；ＮｉｎｇｊｉＢＩ（ＧｕａｎｇｘｉＩｎｓｔｉｔｕｔｅｏｆＴｒａｄｉｔｉｏｎａｌＭｅｄ...     

SYNTHESIS OF 3-PER(POLY)FLUOROALKYLPYRAZOLES

ＳＹＮＴＨＥＳＩＳＯＦ３－ＰＥＲ（ＰＯＬＹ）ＦＬＵＯＲＯＡＬＫＹＬＰＹＲＡＺＯＬＥＳＳＹＮＴＨＥＳＩＳＯＦ３－ＰＥＲ（ＰＯＬＹ）ＦＬＵＯＲＯＡＬＫＹＬＰＹＲＡＺＯＬＥＳ￥ＸｉａｏＱｉｎｇＴＡＮＧａｎｄＣｈａｎｇＭｉｎｇＨＵ（ＳｈａｎｇｈａｉＩｎｓｔｉ...     

PRACTICAL METHOD FOR SYNTHESIS OF NEW GLYCOLIPIDS N－［4（DIALKYL－L－GLUTAMATECARBONYLETHYLCARBO－NYLAMINO）BUTYL］LACTOBIONAMIDES

ＰＲＡＣＴＩＣＡＬＭＥＴＨＯＤＦＯＲＳＹＮＴＨＥＳＩＳＯＦＮＥＷＧＬＹＣＯＬＩＰＩＤＳＮ－［４（ＤＩＡＬＫＹＬ－Ｌ－ＧＬＵＴＡＭＡＴＥＣＡＲＢＯＮＹＬＥＴＨＹＬＣＡＲＢＯ－ＮＹＬＡＭＩＮＯ）ＢＵＴＹＬ］ＬＡＣＴＯＢＩＯＮＡＭＩＤＥＳ￥ＺｈｏｎｇＺｈｉ...     

Analytical assessment of the oscillating chemical reactions by use chemiluminescence detection

This paper introduces the chemiluminescence (CL) detection in oscillating reaction-based determinations using the analyte pulse perturbation technique, a straightforward and expeditious approach to deriving quantitative analytical information from oscillating chemical reactions. The behavior of the H(2)O(2)-KSCN-CuSO(4)-NaOH oscillating system in the presence of luminol was examined by using the proposed detection method and the classical potentiometric technique. Some analytical and practical aspects of both detection systems are discussed. A new analytical method for the determination of vitamin B(6) based on the sequential perturbation produced by different amounts of this substance on the oscillating chemical system was also developed in order to assess the potential of CL detection for routine analyses. The calibration curve thus obtained was linear over the range 0.5-2.0 mumol of vitamin B(6), and the precision and throughput were also quite good (3.04% as RSD and nine samples h(-1), respectively). The proposed method was validated by determining the vitamin in pharmaceutical preparations.     

Nature identification and morphology characterization of anion-exchange membrane fouling during conventional electrodialysis

The aim of this work was to study the effect on the fouling of anion-exchange membranes (AEM) of (1) the pH value of the concentrate solution and (2) the composition in calcium, carbonate, and protein of the diluate solution to be treated by conventional electrodialysis. It appeared that after demineralization of solutions containing CaCl(2) using a concentrate solution maintained at a pH value of 7 or 12, mineral fouling appeared on the AEM surface in contact with the concentrate. The mineral deposits presented a cylindrical filament shape for conditions with a concentrate solution pH value of 7, while, for a pH value of 12, the mineral deposit had a crumbly and spongy texture formed by irregular aggregates. The nature of the fouling was identified as a calcium phosphate with or without calcium hydroxide. In addition, gel-like protein fouling was detected on the AEM surface in contact with the diluate after demineralization procedures using a concentrate pH value of 2 or 7, regardless of the mineral composition of the diluate.     

Flow injection chemiluminescent detection of trace Co(II) with dibromoalizarin violet-H2O2-CTMAB system

Chemiluminescence was observed when dibromoalizarin violet was oxidized with hydrogen peroxide in alkaline solution. Trace amounts of Co (II) catalysed this CL reaction strongly, especially in the presence of the cationic surfactant cetyltrimethylammonium bromide, and the CL intensity was proportional to the concentration of Co(II). A flow injection system with CL detection was established to investigate this CL system. The optimum conditions for this CL reaction were investigated in detail, and the optimized flow injection parameters were determined by the modified simplex method. A CL analytical method for determination of ultratrace amounts of Co (II) was developed with a detection limit of 4 pg/mL. It was used for analysis of natural water samples, and the results compare very well with those from GFAAS. A possible mechanism for this CL reaction is proposed on the basis of studying CL spectra, absorption spectra, fluorescent spectra and HMO treatment for the reagent molecule. The effects of various types of surfactants on CL reaction are also discussed.     

Chemometrics-assisted simultaneous determination of cobalt(II) and chromium(III) with flow-injection chemiluminescence method

In this paper, a flow-injection chemiluminescence (CL) system is proposed for simultaneous determination of Co(II) and Cr(III) with partial least squares calibration. This method is based on the fact that both Co(II) and Cr(III) catalyze the luminol-H(2)O(2) CL reaction, and that their catalytic activities are significantly different on the same reaction condition. The CL intensity of Co(II) and Cr(III) was measured and recorded at different pH of reaction medium, and the obtained data were processed by the chemometric approach of partial least squares. The experimental calibration set was composed with nine sample solutions using orthogonal calibration design for two component mixtures. The calibration curve was linear over the concentration range of 2 x 10(-7) to 8 x 10(-10) and 2 x 10(-6) to 4 x 10(-9) g/ml for Co(II) and Cr(III), respectively. The proposed method offers the potential advantages of high sensitivity, simplicity and rapidity for Co(II) and Cr(III) determination, and was successfully applied to the simultaneous determination of both analytes in real water sample.     

TRIS (perfluoroalkylethyl)silyl alkyl amines as calibration standards for electron ionization mass spectrometry in the mass range of 100–3000 Da

A new fluorinated compound mixture has been developed for the calibration of the double focusing mass spectrometer in the mass range of 100–3000 Da in the positive electron ionization (EI) mode. Current calibration standards for EI have either limited mass range [perfluorotributylamine (PFTBA), perfluorokerosene (PFK), s-triazines (TRIS)] or poor peak intensities with significant chemical background in the instrument for several days (perfluoroalkyl phosphazine). The newly synthesized fluorinated silyl alkyl amines mixture is proposed as a reference/calibration standard for EI-MS. This standard produced abundant parent and fragment ions across the entire mass range without any memory effect.     

Simultaneous determination of Cu(II), Ni(II) and Zn(II) by peroxyoxalate chemiluminescence using Partial Least Squares calibration

It was found that the ions Cu(II), Ni(II) and Zn(II) can attenuate the peroxyoxalate chemiluminescence emission, which was used to develop an analytical procedure for the simultaneous determination of these ions in a stopped-flow system using Partial Least Square (PLS) calibration. Acetonitrile was used to dissolve TCPO and to prepare a mixture of fluorescein, H(2)O(2) and imidazole. These solutions were carried using two peristaltic pumps, while a third pump was employed to propel the aqueous solutions of the metallic ions. All solutions were mixed in the quartz cell of a Campsec CL detector connected to a personal computer to register the CL development using the Clarity software. Under the optimum operative conditions each ion produced a specific CL development with maximum intensities at 0.280 min for Zn(II), 0.307 min for Ni(II) and 0.327 min for Cu(II). The latter exhibited the highest inhibition effect. The experimental calibration set was composed of 16 sample solutions using a central design for three component mixtures with scaled values. The proposed method offers the advantages of simplicity, good precision and accuracy for the simultaneous determination of Ni(2+), Cu(2+) and Zn(2+) in water samples.     

Quantitative nitrogen analysis by Auger electron spectrometry and glow discharge optical emission spectrometry

Nitrides of refractory metals are investigated as diffusion barriers for Cu metallization. The composition, thermal stability and inter diffusion in layered systems are characterized by depth profile analysis. For the quantification of depth profiles determination of sensitivity factors is essential. For nitrogen and other light elements matrix specific standards are often not available and compound standards are used for calibration. We have investigated the systems Ta–N and Ta–Si–N and for comparison Cr–N by means of Auger electron spectrometry (AES) and glow discharge optical emission spectrometry (GDOES). A non-linear calibration curve for the N/Cr intensity ratio was observed with GDOES in the Cr–N-system, probably caused by self-absorption of the Cr line.     

Flow injection chemiluminescence analysis of phenolic compounds using the NCS-luminol system

A flow injection system coupled with two simple and sensitive chemiluminescence (CL) methods is described for the determination of some phenolic compounds. The methods are based on the inhibition effects of the investigated phenols on the CL signal intensities of N-chlorosuccinimide-KI-luminol (NCS-KI-luminol) and NCS-luminol systems. The influences of the chemical and hydrodynamic parameters on the decrease in CL signal intensities of NCS-KI-luminol and NCS-luminol systems for hydroquinone, catechol, and resorcinol, serving as the model compounds of analyte, were studied in the flow injection mode of analysis. Under the selected conditions, the proposed CL systems were used for the determination of some phenolic compound and analytical characteristics of the systems including calibration equation, correlation coefficient, linear dynamic range, limit of detection, and sample throughput. The limits of detection for hydroquinone, catechol, and resorcinol were 0.002, 0.01, and 0.3 μM using the NCS-KI-luminol system; for the NCS-luminol system these were 0.01, 0.17, and 1.6 μM, respectively. The relative standard deviation for 10 repeated measurements of 0.04, 0.06, and 1 μM of hydroquinone, catechol, and resorcinol were 1.9, 1.4, and 2.0%, respectively, with the NCS-KI-luminol system; for 0.2, 0.5, and 4 μM of hydroquinone, catechol, and resorcinol these were 2.6, 2.2, and 3.7%, respectively, using the NCS-luminol system. The method was applied to the determination of catechol in known environmental water samples with a relative error of less than 6%. A possible reaction mechanism of the proposed CL system is discussed briefly.      

Impact of electrodialytic parameters on cation migration kinetics and fouling nature of ion-exchange membranes during treatment of solutions with different magnesium/calcium ratios

During electrodialysis (ED) treatment of solutions with different Mg/Ca ratios (R = 0, 1/20, 1/10, 1/5 and 2/5) and in different pH conditions (acid, neutral and basic), foulings on ion-exchange membranes were previously characterized and identified, by the way of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. A mineral fouling was observed in neutral and basic conditions (for R = 1/5 and 2/5) on the anion-exchange membrane (AEM) concentrate side and in basic conditions on the cation-exchange membrane (CEM) concentrate side as well as on the diluate side for R = 1/5 and 2/5. The objectives of this present work were to link the morphological characterization and identification of membrane fouling to electrodialytic parameters and cation migration kinetics. It appeared that the CEM permselectivity was severely affected in basic conditions for R ≥ 1/5. The consequence of this alteration was the migration of OH⁻ through the CEM, a pH increase in the diluate compartment and different treatment durations. The calcite observed on AEM concentrate side for Mg/Ca ≥ 1/5 would be due first to the particular operating conditions such as the recirculation of the concentrate solution, and also to the supersaturated conditions reached or not at the AEM interface and favourable pH conditions.     

Factors to be considered in the preparation of single and multi-element standards for inductively coupled plasma optical emission spectrometry.

The problems encountered with the production of single and multi-element inductively coupled plasma (ICP) optical emission spectrometry (OES) standards are reviewed. Purity, stability and characterization of starting materials, water and acids have profound effects on the quality of these standards. The trace level contaminants and the form of the starting materials can result in serious analytical errors. Long-term stability of the ICP-OES standard, dependent in part on the storage container composition, plays an important role in the accuracy of ICP-OES calibration. The relationship between inter-element correction factors and the quality of ICP-OES standards is discussed. Finally, some of the factors that must be considered during the manufacture of multi-element standards for instrument calibration, universal and customer-specific applications are delineated.