Direct spectrophotometric method for the determination of cobalt with indane 1,2,3-trionetrioxime in aqueous medium

A simple, sensitive and selective Spectrophotometric method has been developed for the determination of cobalt using indane 1,2,3-trionetrioxime (ITT): The method is based on the colour reaction between ITT and cobalt(II) in sodium acetate-acetic acid buffer (pH 4.5–7.5) medium. The calibration graph for measurement at 320 nm is linear in the range 1.18–23.60g of cobalt per 25 ml, with molar absorptivity of 5.32×10⁴1mol^–1 cm^–1. The effect of interfering ions has been studied and the method was applied to the determination of cobalt in alloys, with good results.     

合并带流动注射分光光度法研究硫羟乳酸掩蔽性能

本文运用合并带流动注射分析技术，建立了以Ｙｂ＾３＋ＸＯ显色体系为参考体系研究硫羟乳酸掩蔽性能的方法，在ｐＨ５．６硫羟乳酸能掩蔽Ｓｎ＾４＋，Ｂｉ＾３＋，Ｔｌ＾３＋，Ｈｇ＾２＋，Ｃｕ＾２＋，Ｃｒ＾３＋和Ｃｄ＾２＋测定Ｙｂ＾３＋的线性范围为１．３６×１０＾－６～２．７２×１０＾－５ｍｏｌ／Ｌ，采样频率可达１２０次／ｈ。     

铂（Ⅳ）—钼酸盐—丁基罗丹明B缔合显色反应的研究

本文研究在聚乙烯醇(PVA)存在下,铂与钼酸铵和丁基罗丹明B(BRB)形成离子缔合物,该缔合物的最大吸收位于570nm,摩尔吸光系数ε值为9.26×10~5L·mol~(-1)·cm~(-1),服从比耳定律范围0～3.0μg Pt/25ml,缔合物至少稳定3周。测定铂的条件为C_(HClO_4)=1.4mol/L,C_(MoO_4~(2-)=1.1×10~(-3)mol/L,C_(BRB)=3.8×10~(-5)mol/L,0.08％PVA。考察了40多种共存离子的影响,除形成杂多酸的元素外,大多数不干扰。本法已用于催化剂和某些铂矿中铂的测定,结果较满意。     

阻抑-褪色光度法测定痕量间苯二酚

在NH3 NH4Cl介质中 ,间苯二酚能阻抑Fe(Ⅲ )为催化剂 ,邻菲罗啉为活化剂的过氧化氢氧化甲酚红的褪色反应。研究了该反应的最佳条件和动力学参数。建立了一种测定痕量间苯二酚的新方法。方法检出限为 3 5× 1 0 - 4 g·L- 1 ,测定范围为 0 .30mg/L～ 7.0mg/L ,方法可用于废水中间苯二酚的测定     

Determination of trace amounts of bromide by flow injection/stopped-flow detection technique using kinetic-spectrophotometric method

A simple, sensitive and selective method for the determination of bromide in seawater by using a flow injection/stopped-flow detection technique was examined. The detection system was developed for a new kinetic-spectrophotometric determination of bromide in the presence of chloride matrix without any extraction and/or separation. The detection was based on the kinetic effect of bromide on the oxidation of methylene blue (MB) with hydrogen peroxide in a strongly acidic solution. Large amounts of chloride could enhance the sensitivity of the method as an activator. The decolorisation of the blue color of MB was used for the spectrophotometric determination of bromide at 746 nm. A stopped-flow approach was used to improve the sensitivity of the measurement and provide good linearity of the calibration over the range of 0-3.2 μg ml⁻¹ of bromide. The relative standard deviation was 0.74% for the determination of 2.4 μg ml⁻¹ bromide (n = 5). The detection limit (3σ) was 0.1 μg ml⁻¹ with a sampling frequency of 12 h⁻¹. The influence of potential interfering ions was studied. The proposed method was applied to the determination of bromide in seawater samples and provided satisfactory results.     

Formation Thermodynamics of Binary and Ternary Lanthanide(III) Complexes with 1,10-Phenanthroline and Chloride in N,N-Dimethylformamide

Formation thermodynamics of binary and ternary lanthanide(III) (Ln = La, Ce, Nd, Eu, Gd, Dy, Tm, Lu) complexes with 1,10-phenanthroline (phen) and the chloride ion have been studied by titration calorimetry and spectrophotometry in N,N-dimethyl-formamide (DMF) containing 0.2 mol-dm^–3 (C₂H₅)₄NClO₄ as a constant ionic medium at 25°C. In the binary system with 1,10-phenanthroline, the Ln(phen)³⁺ complex is formed for all the lanthanide(III) ions examined. The reaction enthalpy and entropy values for the formation of Ln(phen)³⁺ decrease in the order La > Ce > Nd, then increase in the order Nd < Eu < Gd < Dy, and again decrease in the order Dy > Tm > Lu. The variation is explained in terms of the coordination structure of Ln(phen)³⁺ that changes from eight to seven coordination with decreasing ionic radius of the metal ion. In the ternary Ln³⁺-Cl^–-phen system, the formation of LnCl(phen)²⁺, LnCl₂(phen)⁺, and LnCl₃(phen) was established for cerium(III), neodymium(III), and thulium(III), and their formation constants, enthalpies, and entropies were obtained. The enthalpy and entropy values are also discussed from the structural point of view.     

7-(对甲酰基苯偶氮)-8-羟基喹啉-5-磺酸的合成及其双波长分光光度法测定镓

7－（对甲酰基苯偶氮）－8－羟基喹啉－5－磺酸是一新显色剂。该试剂在微碱性介质中（pH＝7．5）与镓形成黄色络合物。络合物λmax＝392nm，摩尔吸光系数ε392＝2．24×104L·mol-1·cm-1。同时在500nm呈现负峰，用双峰观波长法测定镓ε392～500＝6．89×104L·mol-1·cm－1，灵敏度是单波长法的三倍多．线性范围0～2．0×10－5mol／L。用拟定的方法测定了掺硅的GaAS材料及岩石中的镓，加入回收率为106％～110％；方法的相对标准偏差小于1．6％。     

Ion-pair adsorption film colorimetry — A new simple method for ppb level of aluminum ion in water sample

A new, highly sensitive and simple colorimetric method for trace aluminum(III) with 2,2-dihydroxyazobenzene, H₂L, is described, based on the ion-pair adsorption of the anionic Al chelate, [A1L₂ ^–, with crystal violet cation, CV⁺, on the surface of Polyvinylchloride film plasticized with dioctylphthalate. The blue violet species, CV⁺[A1L₂]^–, is enriched onto the transparent film, leading to a remarkable enhancement of the sensitivity, and the detection limits are 3 ng/ml by spectrophotometry and 5 ng/ml by visual colorimetry, respectively. Using spectrophotometer, a linear calibration curve is obtained over the concentration range of 0 to 50 ng/ml of Al. Further, the color system, consisting of red ([A1L₂]^–), yellow (H₂L), and blue violet (CV⁺), gave clear color changes suitable for visual determination of aluminum with an applicable range of 0 to above 3000 ng/ml. The four different color zones are khaki for 0–5 ng/ml, reddish-brown for 5–200 ng/ml, blue violet for 200 ng/ml-3g/ml, and colorless for more than 3g/ml. The proposed method has been successfully applied for the determination of aluminum in tap waters.     

Ammonium tetraphenylborate-naphthalene adsorbent for the preconcentration and trace determination of uranium in standard alloys and synthetic samples using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol by fourth-derivative spectrophotometry

A solid ion-pair material produced from ammonium tetraphenylborate (ATPB) and naphthalene has been used for the preconcentration of uranium from the large volume of its aqueous complex samples. Uranium reacts with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) to form a water insoluble, coloured complex. This complex is quantitatively retained on the ATPB-naphthalene adsorbent filled in a column in the pH range 7.0–9.5 and at a flow rate of 2 ml/min. The solid mass from the column is dissolved with 5 ml of dimethylformamide (DMF) and uranium is determined by fourth-derivative spectrophotometry. The calibration curve is linear over the concentration range of 0.13–15.0 g of uranium in 5 ml of the final DMF solution. Seven replicate determinations of 6 g of uranium gave a mean peak height (peak-to-peak signal between 592 nm and 582 nm) of 1.02 with a relative standard deviation of 0.95%. The sensitivity is 0.8419 (d⁴A/d⁴)/(g ml^–1) found from the slope of the calibration curve. The interference of a large number of anions and cations on the estimation of uranium has been studied and the method applied for the determination of uranium in coal fly ash, Zr-base alloy and some synthetic samples corresponding to standard alloys.     

Sensing of Trace Amounts of Dodecyl Benzene Sulfonate by Solid Phase Spectrophotometry

A very simple, selective and sensitive spectrophotometric method for the determination of dodecyl benzene sulfonate (DBS) has been investigated. In this method, the ion pair of DBS and methylene blue was adsorbed onto plasticized poly(vinylchloride) membrane as a solid phase extraction medium. The absorbance of the blue membrane was measured at 660nm against a blank membrane using a spectrophotometer. The influence of type and amount of plasticizer, pH, concentration of methylene blue, temperature of sample solution and time of extraction on the absorbance of membrane was studied. Linear calibration was obtained over a concentration range of 0.1 to 6.5µgmL^–1 of DBS. The method was applied to the determination of DBS in different commercial detergents. The precision and accuracy of the method is comparable with the conventional standard method. This method is cost-effective, and the use of organic solvent such as chloroform is completely eliminated.