液相化学发光法测定微量硒

以碘－鲁米诺化学发光反应作指示反应,利用硒（Ⅳ）对Ｃｒ（Ⅵ）－ＫＩ反应的催化作用,提出了测定微量硒的新方法。方法的检出限为２．３＊１０＾－１１ｇ／ｍＬ,线性范围为１．０＊１０＾－１０－１．０＊１０＾－７ｇ／ｍＬ。该方法简单,快速,准确度较高,用于茶叶和人发中硒的测定,结果满意。     

四种双冠醚的铯离子选择电极

以合成的四种双（苯并－１８－冠－６）为中性载体制成了ＰＶＣ膜铯离子电极。研究了载体结构，电极膜组成和内充液浓度与电极性能的关系，以邻苯二甲酸二辛酯增塑的４＇，４＂－（邻－亚苯基二氧亚甲基）双（苯并－１８－冠－６）铯离子电极的选择性较好，Ｋ＾ｐ＾ｏ＾ｔＣｓ，ｋ＝２．４×１０＾－＾２，２０℃时，该电极的线性响应范围为５×１０＾－＾５－５×１０＾－＾２ｍｏｌ／Ｌ（ＣｓＣｌ），斜率接近理论值。     

（E）—2—甲基—1,3—戊二烯的振动光谱及其稳定构象的研究

记录了（Ｅ）－２－二甲基－１，３－戊二烯的固，液，气态ＦＴＩＲ光谱（４００～４０００ｃｍ＾－１）和固、液态Ｒａｍａｎ光谱（５０～４０００ｃｍ＾－１），观测了６８５及６５８ｃｍ＾－１谱线的变温ＦＴＩＲ光谱（－７３～１０℃），对所得谱图进行了指认分析发现，该化合物存在两种单键旋构象异构体ｓ－ｔｒａｎｓ和ｓ－ｃｉｓ，由变温ＦＴＩＲ光谱峰强度随温度的变化得到了这两种构象互变的△Ｈ＾０和△Ｓ＾０。     

偶合反应流动注射化学发光测定锆的研究

基于Ｚｒ置换Ｃｏ－ＮＴＡ配合物中的Ｃｏ（Ⅱ）和Ｃｏ（Ⅱ）催化过氧化氢氧化鲁米诺产生化学发光的反应，建立了偶合反应流动注射化学发光测定锆的新方法。方法的线性范围为１×１０＾－１０－１×１０＾－７ｇ．ｍｌ＾－１，检出限为３×１０＾－１１ｇ．ｍｌ＾－１，方法用于地矿术中锆的测定，结果满意。     

以偶合反应流动注射化学发光法测定铅

基于Ｐｂ（Ⅱ）能置换出Ｆｅ（Ⅱ）－ＥＤＴＡ络合物中的Ｆｅ（Ⅱ）和Ｆｅ（Ⅱ）－鲁米诺－溶解氧产生化学发光的反应，建立了置换偶合反应流动注射化学发光测定痕量铅的新方法。本方法线性范围１×１０＾－７￣１×１０＾－５ｇ／ｍＬ，相对标准偏差为２．５％（ｎ＝１１，Ｃ＝１０＾－６ｇ／ｍＬ），检出限为２×１０＾－８ｇ／ｍＬ。用于污水中铅的测定，结果令人满意。     

用流动注射法研究巯基化合物—铈（IV）—氢化可的松的化学发光反应

采用流动注射法研究了巯基化合物－铈（Ⅳ）－氢化可的松（ＨＣＲｓ）体系的化学发光行为，对影响化学发光强度的诸因素进行试验和探讨，建立了流动注射化学发光法检测谷胱甘肽（ＧＳＨ），半胱氨酸（Ｃｙｓ）等含巯基化合物的新方法。检测ＧＳＨ和Ｃｙｓ和线性范围分别为２．０×１０＾－６￣１０．０×１０＾－５ｍｏｌ／Ｌ和１．０×１０＾－６ｍｏｌ／Ｌ￣１０．０×１０＾－５ｍｏｌ／Ｌ；检测限分别为２．０×１０＾－７ｍｏｌ     

1—（5—溴—2—吡啶偶氮）—2—萘酚—6—磺酸与铁（Ⅱ）显色反应的研究及其应用

本研究了１－（５－溴－２－吡啶偶氮）－２－萘酚－６－磺酸（５－Ｂｒ－ＰＡＮ－Ｓ）与铁（Ⅱ）的显色反应，试验表明，在ｐＨ３－１０范围内铁（Ⅱ）与５－Ｂｒ－ＰＡＮ－Ｓ型成稳定的络合物，络合物在５５０ｎｍ和７５０ｎｍ有二个吸收峰，其表现摩尔吸光系数分别为２．３１×１０＾４和１．７７×１０＾４Ｌ．ｍｏｌ＾－＾１．ｃｍ＾－＾１。络合物组成比为铁（Ⅱ）：５－Ｂｒ－ＰＡＮ－Ｓ＝１：２，络合物稳定常数为１．８２     

含有吸附络合物溶液的倒数示波计时电位法的应用

Ｐｂ（Ⅱ）在０．２％乙二胺－５×１０＾－３ｍｏｌ·Ｌ＾－１ＨＯｘ－０．３ｍｏｌ·Ｌ＾－１ＫＯＨ溶液中，有良好的全数示波图，其峰电位Ｅｐ＝－１．０５（ｖｓ．ＳＣＥ），峰高与Ｐｂ＾２＋溶度在４．０×１０＾－７～２．０×１０＾－５ｍｏｌ·Ｌ＾－１内成正比，检测下限可达２．０×１０＾－７ｍｏｌ·Ｌ＾－１。本实验采用倒数示波计时电位法对铝合金“Ａ”中铅进行了测定，并直接通过示波图，对络合物的吸附属于性进行了     

八乙墓卟啉和四苯基卟啉合钌(Ⅱ)及锇(Ⅱ)的二氧加合物的红外光谱

ＯＥＰ（八乙基卟啉阴离子）和ＴＰＰ（四苯基卟啉阴离子）合钌（Ⅱ）和锇（Ⅱ）的二氧加合物由ｍａｔｒｉｘ分离技术得到（Ｔ＝２０－４３Ｋ，Ｐ＝１０＾－５－１０＾－６ｔｏｒｒ）。为了确定ν（Ｏ２）带的归属应用于同位素取代法＾１６Ｏ２／＾１８Ｏ２。ＩＲ谱说明对于钌的两种加合物（指ＯＥＰ和ＴＰＰ）都有两种异构体，其ν（＾１６Ｏ２）频率为：Ｒｕ（ＯＥＰ）Ｏ２，１１４１和１１０３ｃｍ＾－１；Ｒｕ（ＴＰＰ）Ｏ２，１     

萃取法研究混配配合物中配体间的芳环堆积作用Ⅲ．Cu2+-phen-PCA-体系

用萃取法研究Ｃｕ＾２＋－ｐｈｅｎ－ＰＣＡ＾－体系中配体间的芳环堆积作用（ｐｈｅｎ＝１，１０－邻菲罗啉，ＰＣＡ＾－＝苯甲酸根（Ｂｚ＾－）、α－苯乙酸根（ＰＡｃ＾－）、β－苯丙酸根（ＰＰｒ＾－）和γ－苯丁酸根（ＰＢｕ＾－），结果表明，配合物中芳环堆积作用依赖于ＰＣＡ＾－事苯环与羧酸根间碳链的长度，其顺序为：Ｂｚ＾－〈ＰＡｃ＾－〈ＰＰｒ＾－〈ＰＢｕ＾－。     

Determination of Aluminum in Drinking Waters by A.C. Oscillopolarography in a Lithium Chloride System

Abstract

A new and convenient method for the rapid determination of aluminum in drinking waters using a.c. oscillopolarography in a lithium chloride system is described in this paper. The calibration graph is linear from 5 × 10^?6 to 8 × 10^?5 mol/L with a detection limit of 5 × 10^?6 mol/L. The relative standard deviation of the method is 4.7% for 4 × 10^?5 mol/L Al. Compared with other techniques, this method has the significant advantages of simple instrumentation, no deaeration procedure required and rapid measurement. It was particularly suitable to the analysis of 10^?6 ~ 10^?5 mol/L levels of Al in drinking waters.     

Electrocatalytic oxidation of dopamine at the polyglycine chemically modified carbon fiber bundle electrode and its voltammetric resolution with uric acid

A polyglycine chemically modified electrode shows substantial catalytic ability towards dopamine (DA). The calibration graph obtained by linear sweep voltammetry for DA is linear in the range 2.0 × 10^–8～ 4.4 × 10^–6 mol/L and the detection limit is ca. 5.0 × 10^–9 mol/L. The catalytic ability towards DA results in the voltammetric resolution of DA and uric acid (UA) in the same solution, which is impossible at the unmodified electrode. Uric acid in less than 120-fold excess does not interfere with the determination of DA.     

Voltammetric determination of cadmium(II) using a chemically modified electrode

An 1-(pyridylazo)-2-naphthol modified glassy carbon electrode has been investigated as sensor for the measurement of trace levels of Cd²⁺. Cd²⁺ is deposited on the surface of a PAN modified glassy carbon electrode at –1.10 V (vs. SCE) via forming Cd²⁺–PAN and subsequent reduction at the electrode. In the following step, Cd-PAN is oxidized, and voltammograms are recorded by scanning the potential in a positive direction. Calibration plots were found to be linear in the range 2 × 10^–8 mol/L to 8 × 10^–7 mol/L. The detection limit was 5 × 10^–10 mol/L, and the coefficient of variation, determined on one single electrode at a concentration of 5 × 10^–7 mol/L, was calculated to be 3.2% (n = 5). Using this new kind of modified electrode, trace levels of Cd(II) in water samples were determined; the average recovery was calculated to be 98.78%. Received: 17 August 2000 / Revised: 19 December 2000 / Accepted: 27 December 2000     

CRITICAL CONCENTRATIONS OF α(1→3)-D-GLUCAN FROM LENTINUS EDODES IN NaOH AQUEOUS SOLUTION

Critical concentrations of α-(1→3)-D-glucan L-FV-Ⅱ from Lentinus edodes were studied by viscometry andfluorescence probe techniques. The dependence of the reduced viscosity on concentration of the glucan in 0.5 mol/L NaOHaqueous solutions with or without urea showed two turning points corresponding to the dynamic contact concentration c_s andthe overlap concentration c~* of the polymer. The values of c_s and c~* were found to be 1×10~(-3) g cm~(-3) and 1.1×10~(-2) g cm~(-3),respectively, for L-FV-Ⅱ in 0.5 mol/L NaOH aqueous solutions. The two critical concentrations of L-FV-Ⅱ in 0.5 mol/LNaOH aqueous solutions were also found to be 1.2×10~(-3) g cm~(-3) fbr c_s and 9.2×10~(-3) g cm~(-3) for c~* from the concentrationdependence of phenanthrene fluorescence intensities. The overlap concentration c~* of L-FV-Ⅱ in 0.5 mol/L NaOH aqueoussolutions was lower than that of polystyrene with same molecular weight in benzene, owing to the fact that polysaccharidetends to undergo aggregation caused by intermolecular hydrogen bonding. A normal viscosity behavior of L-FV-Ⅱ in 0.5 mol/L urea/0.5 mol/L NaOH aqueous solutions can still be observed in an extremely low concentration range at 25℃.     

Analysis of various very slightly water soluble drugs in micellar medium

A potentiometric and/or visual method for the determination of sulphamethoxazole (SULF) in pure form in the range of 5.3 × 10^–5 to 5.0 × 10^–4 mol/L is proposed. To enhance the solubility, the determination has been carried out in a micellar medium formed by an aqueous 5.0 × 10^–2 mol/L N-hexadecyl-N,N,N-trimethyl ammonium bromide (CTAB) solution which increases the dissociation constant K of SULF about tenfold. The titration is performed with NaOH (2.5 × 10^–3 or 5.0 × 10^–2 mol/L) and the end-point is determined by the second derivative graph. The results agree with those obtained by the official method of the USP XXIII. The method is simple, accurate, economical and can successfully replace the more complicated, more expensive and time-consuming existent procedures which are carried out in a non-aqueous medium.     

Detection of Human Serum Albumin by a Photoinduced Fluorogenic Reaction

ABSTRACT

9,10-anthraquinone (AQ), a photochemically reactive substrate, has been conjugated together with human serum albumin (HSA), and the photoinduced fluorogenic reaction of the HSA-AQ conjugate was studied. This conjugate shows a greatly enhanced photochemical fluorimetric activity compared with that of free AQ. The spectral characteristics of the photoreduction product of the HSA-AQ conjugate was investigated and large blue shifts in both the excitation and emission bands, compared with those of free AQ, were observed. The kinetic behavior of the photoinduced fluorogenic reaction and the effects of some experimental conditions were also investigated. The enhancement in the photoinduced fluorogenic reactivity of HSA-AQ was utilized in the sensitive detection of HSA by a simple in-situ photoinduced kinetic fluorimetric method. The calibration graph was linear over the range 0-1.0x10^?6 mol/L HSA. The detection limit was 6.5x10^?10 mol/L HSA and the relative standard deviation was 2.7% for 6.0x10^?8 mol/L HSA (n=6).     

Chemiluminescence flow system for the determination of sulfite

A novel chemiluminescence(CL) flow system for sulfite is described based on electrostatically immobilized luminol on an anion exchange column. Sulfite is detected by the CL reaction with luminol bleeding from the column by hydrolysis. The calibration graph is linear in the range 3 × 10^–7 to 1 × 10^–5 mol/L, and the detection limit is 1 × 10^–7 mol/L. Interfering metal ions co-existing in sample solutions could be effectively eliminated on-line by an upstream cation exchanger. A complete analysis could be performed in 1 min with a relative standard deviation of less than 5%. The system could be reused for over 50 h and has been applied successfully to the determination of sulfur dioxide in air.     

Determination of Lysine in Nutrition Sample by Adsorption Voltammetry

Abstract

Lysine can be determined by adsorptive voltammetry after derivatization with acetaldehyde in 1.3 x 10^?2mol/ L borax-NaOH buffer solution (containing 4 x 10^?3mol/ L of CH₃CHO at pH10). The Schiff's base product of the derivation can be adsorbed on a hanging mercury electrode and reduced with peak potential of about -1.33v (vs.SCE) after 120s pre-concentration time. The derivative peak height is linearly proportional to the concentration for lysine in the range 6.0 x 10^?7-1.0 x 10^?5mol/ L. The detection limit is 4.0 x 10^?7mol/ L. Using this method, we have directly determined lysine in nutrition samples without any pre-separation step.     

Sensitive and selective determination of mercury by differential pulse stripping voltammetry after accumulation of mercury vapour on a gold plated graphite electrode

 A selective and sensitive method is proposed for the determination of mercury by anodic stripping voltammetry after its preconcentration from the gas phase. Mercury from the sample solution is reduced to elemental Hg by SnCl₂ and volatilized by the bubbles of a carrier gas. The gas containing mercury vapour is dried and passed through a capillary onto a gold coated graphite electrode. An anodic stripping voltammogram is recorded from 0.1 mol/l HClO₄+3×10^-3 mol/l HCl solution. The calibration curve is linear from 1×10^-9 to 4×10^-8 mol/l Hg(NO₃)₂. The absolute detection limit is 0.46 ng Hg. The relative standard deviations for 4×10^-9 mol/l and 2×10^-8 mol/l Hg(NO₃)₂ are 9.8% and 6.1%, respectively (n=5). Received: 18 December 1995/Revised: 16 April 1996/Accepted: 20 April 1996     

Adsorptive Voltammetric Measurement of Trace Level of Iron(III) with 4–(2–Pyridylazo) Resorcin

Abstract

The polarographic behavior of the complex of iron–4– (2–pyridylazo) resorcin(PAR) was studied. In HAc– NaAc– EDTA buffer solution, the complex can be adsorped on a hanging mercury drop electrode giving a sensitive adsorptive complex reduction peak with a peak potential at -0.36V(vs. SCE). Optimum experimental conditions were found by the use of 0.08mol/L HAc, 0.06mol/L NaAc, 5.0 × 10^?3mol/L EDTA and 1.0 × 10^?5mol/L PAR. With preconcentration for 60s, the derivative peak height of the complex compound is linearly proportional to the concentration for Fe in the range from 1.0 × 10^?9mol/L to 1.0 × 10^?7mol/L. For a 2–min pre–concentration time, the detection limit found was 2.0 × 10^?10mol/L. This method has high sensitivity and selectivity. It has been applied to the determination of trace iron in food and water samples without any pre–separation step.