Kinetic spectrophotometric determination of hydrazine

A sensitive kinetic method for determining low levels of hydrazine has been described. The method is based on the measurement of the rate of the reaction between hydrazine and Mo(VI) in the presence of hydrochloric acid. The redox reaction was monitored spectrophotometrically at 710 nm. The variable-time and fixed-time methods were used. The calibration graph was linear for hydrazine concentrations of 1.0 × 10⁻⁴-1.4 × 10⁻² M, using the fixed-time method of analysis. The method is simple, rapid, precise, sensitive and widely applicable.     

Kinetic spectrophotometric determination of hydrazine

A kinetic spectrophotometric method for hydrazine determination in the range of 9.36×10⁻⁷ to 4.37×10⁻⁵ mol dm⁻³, based on the inhibitory effect of hydrazine on the oxidation of Victoria Blue 4- R by KBrO₃, was developed and validated. Kinetic parameters are reported for both the indicating and the inhibiting reaction. The detection limit was established as 9.98×10⁻⁸ mol dm⁻³. The selectivity of the proposed method was tested considering the influence of different ions that may be present in real samples. The method was successfully applied for hydrazine determination in various samples (very pure water from the water-steam system of a power plant and Isoniazid tablets, a pharmaceutical product).      

Direct spectrophotometric determination of indium in tin

Indium is separated from tin by an anion-exchange process in 0.5 M hydrochloric acid solution. Subsequently, the indium is extracted into 1,2-dichlorobenzene as its complex with 5,7-dichloro-8-quinolinol. The complex forms and extracts quantitatively in the pH range 3–7. The yellow, organic phase is measured spectrophotometrically at 415 mμ; ; its absorbancy is directly proportional to the indium content of the aqueous phase up to a total of 1.5 mg of indium per 50 ml. This procedure quantitatively separates the two metals, allows one to determine the indium content of indium(<5%)-tin alloys with a relative error less than 0.7%, and considerably reduces color fading errors inherent in some previously reported spectrophotometric methods for indium.     

Kinetic determination of alcohols and their binary mixtures with a stopped-flow spectrophotometric technique

The kinetic method described for the determination of a single alcohol (? 5 X 10^-4 M), or of a binary mixture of alcohols in aqueous solution is based on fast oxidation by silver(II), monitored spectrophotometrically by using a stopped-flow technique. Mixtures of alcohols having rate constants differing by a factor of ?3 can be resolved. The lower limit of determination is ca. 5 × 10^-4 M.     

动力学光度法测定食品中的碘

催化动力学光度法测定痕量碘 ,大多使用Ｃｅ(ＩＶ) -Ａｓ(ＩＩＩ)体系[1 3] 。我们的实验发现在硫酸介质中 ,Ｉ- 能强烈催化高碘酸钾氧化苋菜红的褪色反应 ,在波长 5 2 5ｎｍ处 ,其反应速度与碘离子的浓度之间符合动力学一级反应关系式 ,并且此法灵敏度、选择性均较高。1　实验部分取两支 2 5ｍｌ比色管 ,各加入 2 0ｍｌ浓度为8 0× 1 0 - 3ｍｏｌ/Ｌ苋菜红溶液 ,3 5ｍｌ( 1 0ｍｏｌ/Ｌ)Ｈ2 ＳＯ4,2 0ｍｌＫＩＯ4( 0 2 0ｍｏｌ/Ｌ)溶液。向其中一支加入适量碘标准溶液 ( 1 μｇ/ｍｌ) (吸光度为Ａ) ,另一支不加碘 (吸光度为Ａ0 ) ,用水…     

动力学光度法测定痕量甲醛

在稀硫酸溶液中,甲醛对KClO3氧化罗丹明6G褪色反应有催化作用,研究了其动力学条件,建立了测定痕量甲醛的动力学光度分析方法,线性范围为0.02～1.8μg/mL,检出限为1.5×10-8g/mL。该法用于湖水、饮料和漆料中痕量甲醛的测定,标准加入回收率为93.8%～108.5%,RSD为2.6%～3.4%。     

Kinetic determination of adrenaline,l-dopa and their mixtures with a stopped-flow spectrophotometric technique

Catecholamines (adrenaline and L-Dopa) can be determined by a stopped-flow spectrophotometric technique. For individual determinations, catecholamines are oxidized to the corresponding o-benzoquinones by hexachloroiridate(IV). Concentrations in the range 2·10^-4–2·10^-3 M can be determined with errors of about 2 %. For evaluation of mixtures, aminochromes are formed. The method allows a catecholamine concentration of about 5·10^-6 M to be determined in the presence of a ten-fold amount of another catecholamine, with a maximum error of about 10 %.     

Kinetic spectrophotometric determination of Tween 80

A novel kinetic spectrophotometic method for the determination of Tween 80 based on its interaction with 5(p-dimethylaminobenzylidene)rhodanine (PDR) in alkaline media is reported. The effect of variable on the rate of interaction of Tween 80 and PDR was investigated in order to establish the optimum conditions. The interaction was monitored spectrophotometically and change in absorbance (ΔA) of PDR at 464 nm at times of 30 and 270 s was used as an analytical parameter. Tween 80 can be measured in the range of 2.5×10⁻⁵ to 1.25×10⁻³ M with detection limit of 1.5×10⁻⁵ M. The relative standard deviation for eight replicate determinations of 2×10⁻⁴ and 1×10⁻³ M of Tween 80 solution was 4.08 and 3.88%, respectively. This method was used to determine Tween 80 in biscuit and multivitamin syrup.     

Atomic absorption spectrometric determination of indium in gallium arsenide

Summary The determination of indium in heavily doped gallium arsenide (0.2–1.2 mg g^–1 In), by both electrothermal and flame AAS is reported. The sample is first decomposed with nitric acid and the diluted solution is atomized by employing the more convenient technique. The conventional air-acetylene flame is used for samples containing at least 1 mg g^–1 indium. For lower concentrations the electrothermal atomization is required and matrix-matched standards become necessary. Platform sampling is shown to improve both sensitivity and repeatability in comparison with the tube-well sampling. Dependence of the matrix effect on both the signal measurement mode and deterioration of the platform is examined. By increasing the sample mass up to 100 mg, without further dilution of the solution to be injected into the furnace but with the optical correction of the background, a detection limit (6 s) of 4.2 ng g^–1 (1.2×10¹⁴ atoms cm^–3) is achieved. The method was applied to In doped GaAs samples and the results are compared with those independently obtained by differential pulse polarography.

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AAS-Bestimmung von Indium in Galliumarsenid

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This work was presented at the Euroanalysis VI Conference (Paris, September 7–11, 1987)     

Kinetic spectrophotometric determination of traces of sulfide

A method for the determination of sulfide based on the addition reaction of sulfide with magenta at pH 7 and 25 degrees C is described. The decrease in absorbance of magenta at 540 nm, its lambda(max), over a fixed time is proportional to the concentration of sulfide over the range of 25-2500 ng ml(-1). The limit of detection was found to be 15 ng ml(-1). Ten replicate analysis of a sample solution containing 1.5 mug ml(-1) sulfide gave a relative standard deviation of 0.8%. The effects of various cations and anions on sulfide determination have been reported and procedures for removal of interferences have been described.     

Kinetic spectrophotometric determination of amodiaquine and chloroquine

Abstract  

Two simple, sensitive, and selective spectrophotometric methods were developed for determining amodiaquine (AQ) and chloroquine (CQ) based on their oxidation with potassium iodate and potassium bromate, respectively. The initial rates of oxidation of AQ and CQ were monitored at 342 and 343 nm, the wavelengths of maximum absorptions of the two drugs. The various experimental parameters affecting oxidation reactions were thoroughly studied and optimized. Beer’s law was obeyed for 0.2–4.0 and 0.5–5.0 μg cm⁻³, with correlation coefficients of 0.9999 and 0.9998 (n = 6) and a detection limit (based on the 3S _b -criterion) of 0.04 and 0.06 μg cm⁻³ for AQ and CQ. The proposed methods were conveniently applied to determining AQ and CQ in pure and dosage forms.     

Kinetic spectrophotometric determination of amodiaquine and chloroquine

Abstract  Two simple, sensitive, and selective spectrophotometric methods were developed for determining amodiaquine (AQ) and chloroquine (CQ) based on their oxidation with potassium iodate and potassium bromate, respectively. The initial rates of oxidation of AQ and CQ were monitored at 342 and 343 nm, the wavelengths of maximum absorptions of the two drugs. The various experimental parameters affecting oxidation reactions were thoroughly studied and optimized. Beer’s law was obeyed for 0.2–4.0 and 0.5–5.0 μg cm⁻³, with correlation coefficients of 0.9999 and 0.9998 (n = 6) and a detection limit (based on the 3S _b -criterion) of 0.04 and 0.06 μg cm⁻³ for AQ and CQ. The proposed methods were conveniently applied to determining AQ and CQ in pure and dosage forms. Graphical abstract        

Polarographic determination of mixtures of aluminum and gallium

Methods have been described for determining mixtures of aluminum and gallium when the ions are present in approximately the same concentration and when the concentration of aluminum exceeds the concentration of gallium by at least a factor of five. The average error of the determination of aluminum is ±4 to 8% and that of gallium is ± 6 to 8%.     

Spectroscopy of laser-excited indium,gallium and indium–gallium systems

The spectroscopy of dense Ga, In and In–Ga vapours is studied via resonant pulsed laser excitation at 403.4 nm (Ga) and 410.3 nm (In). Besides some known atomic Rydberg levels emission, satellite wings on the blue side of the fundamental transitions show up both in the homonuclear and heteronuclear vapours. They are due to the presence of excited homonuclear dimers that form in the collision between excited and ground-state atoms. The formation of heteronuclear dimers is inferred by the time-resolved analysis of some atomic fluorescences.     

Kinetic spectrophotometric determination of nanogram amounts of cyanide

A sensitive kinetic method for determination of nanogram amounts of cyanide is reported. It is based on the measurement of the induction period imposed by cyanide on the copper(II)-catalysed oxidation of 3-hydroxybenzaldehyde azine (3-OHBAA) by potassium peroxydisulphate. Kinetic data are recorded spectrophotometrically at 465 nm, the maximum absorption wavelength of the oxidation product of 3-OHBAA. From the kinetic study and other experimental tests it may be concluded that the cyanide ion undergoes copper(II)-catalysed oxidation during the induction period. The calibration plot is linear in the range 150-600 ng/ml cyanide and the detection limit is 50 ng/ml. The precision of the method, expressed as the relative standard deviation, is 3.2% for 350 ng/ml cyanide. Good recoveries are obtained in applying the method to analysis for cyanide in water samples.     

靛蓝胭脂红-溴酸钾体系催化光度法测定微量碘

研究了在室温及0．4mol/L H2SO4介质中碘离子对KBrO3氧化靛蓝胭脂红褪色反应的催化作用,建立了一种测定微量碘的新方法。碘离子浓度在0．20－2．0μg/mL范围内与△A呈线性关系,检测限为0．14μg/mL。多数常见离子无干扰。可用于海带中微量碘的测定。     

铟的灵敏光度测定法

我国对微量铟的显色反应研究得较少.最常用的是碱性染料萃取光度法,但操作冗繁而且苯的毒性较大.因此寻找灵敏度高而又能在水相测定铟的新方法是很有必要的. 用苯荧光酮(2,3,7-三羟基-9-苯基-6-荧光酮,PF)作显色剂的胶束增溶分光光度法已应用于锗、钼、锡、镓等的测定,但用类似的方法测铟则尚未见报道.我们的实验证明,在pH为7.7～8.9的醋酸-氢氧化铵缓冲介质中,铟与PF及氯化十六烷基吡啶(OPC)生成玫瑰红色的三元配合物,其配合比为In(III):PF:CPC=1:2:2,表观稳定常数为8.6×10~(10),摩尔吸收系数达1.28×10~5.提出用乙酸乙酯萃取分离杂质.利用本显色反应测定微量铟,方法灵敏且稳定,准确度和精密度均较好.     

Kinetic spectrophotometric determination of ethamsylate in dosage forms

A simple and sensitive kinetic method has been developed for the determination of ethamsylate (ESL) in its pharmaceutical preparations. The method is based upon oxidation of ESL with 3-methyl-2-benzothiazolinone hydrazone hydrochloride in presence of cerium (IV) ammonium sulfate at room temperature for 20 min. The absorbance of the reaction product is measured at 514 nm. The absorbance-concentration plot was rectilinear over the range of 4-30 microg/mL (r = 0.9999). The lower detection limit was 0.267 microl/mL (9.110 x 10(-6) M) and the lower quantitation limit was 0.808 microg/mL. The different experimental parameters affecting the development and stability of the reaction product were studied and optimized. The proposed method was applied to the determination of ESL in formulations, and the results obtained were in good agreement with those obtained using a reference method. The proposed method was also used for the in vitro detection of ESL in spiked human plasma at its therapeutic concentration level.     

阻抑动力学光度法测定乳品中的痕量碘

研究了在稀H2SO4介质中,痕量I-对KBrO3氧化酸性品红的阻抑作用及其动力学条件,建立了测定痕量I-的阻抑动力学光度分析的新方法.测定I-的线性范围为0～0.04 μg/mL,检出限为1.1×10-9 g/mL.已用于乳品中痕量碘的测定.