A revised method for the spectrophotometric determination of glyoxylic acid

The spectrophotometric determination of glyoxylic acid at 520 nm based on formation of the 1,5-diphenyl formazan derivative is revised. The colour can be developed at room temperature if the acid or its sodium salt is pure. The molar absorptivity is improved to 32 250 l mol^?1 cm^?1. The differences from the earlier procedures are discussed.     

A spectrophotometric method for quantitative determination of lactulose in pharmaceutical preparations

A simple spectrophotometric assay for the quantification of lactulose in pharmaceutical preparations was developed. The method is based on hydrolysis of lactulose under acidic conditions. The hydrolyzed product reacts with resorcinol, giving absorption peaks at 398 and 480 nm. Both absorption wavelengths can be used for the determination of lactulose. The limit of detection of lactulose at 398 nm and 480 nm was 0.075 μg mL⁻¹ and 0.65 μg mL⁻¹, respectively. The calibration was linear in the range of 5–25 μg mL⁻¹. Analytical conditions were optimized, and the method was validated for analysis of pharmaceutical preparations. The determined amount of lactulose was found to be in good agreement with labeled claims in commercial products. The proposed method is economical, convenient, and suitable for the quantification of lactulose in pharmaceutical preparations. The text was submitted by the authors in English.     

动力学抑制光度法测定氨三乙酸

氨三乙酸在分析化学中常作为配位滴定剂和掩蔽剂,在催化动力学分析中常作为活化剂。常量的氨三乙酸的测定已有工业化方法,微量氨三乙酸的测定方法极少。酸性和沸水浴条件下,微量的氨三乙酸对高碘酸钾氧化偶氮胭脂红B褪色的反应具有显著的抑制作用,据此建立     

A spectrophotometric method for uranium determination

A very sensitive extraction spectrophotometric method for the analysis of uranium based on the extraction of a uranium—benzoate—crystal violet complex by a mixture of xylene and benzene is described. The absorbance maximum is at 606 nm and molar absorptivity is 4.28·10⁴ l·mol⁻¹·cm⁻¹. The interference due to a number of anions and cations studied without any pre-extraction was found to be within permissible limits. The method has been used for determining uranium in a synthetic solution, i.e., uranium in the presence of various other ions. The interference due to some cations was eliminated by the use of a masking agent (boric acid).     

A spectrophotometric method for the determination of thorium with acid alizarin black Sn

Acid alizarin black SN reacts with thorium at pH 4.2 to give a highly sensitive colour reaction with thorium, ε₆₀₀ mμ = 28,000. There is no interference from Ba, Ca, Cd, Ce(III), Gd, Hg, La, Mg, Mn, Pb, Pr. Sm, Sr, Zn, Zr, Cl(su-), CN(-), I(su-), NO(3-), SO₄^2-. The interferences of Al, Bi, Co, Cu, Fe, Ni, Mo, Sb, Sn, Ti and W may be overcome by addition of masking agents. Only U(VI) and V(V) still interfere and these can be determined sequentially with the thorium. The nature of the complex is studied and the mode of its formation.     

A spectrophotometric method for the determination of nickel

A photometric method for the determination of nickel using versene is described. Up to 20 mg of nickel can be determined with a maximum deviation of ± 0.10 mg. The effect of interfering elements, concentrations, accuracy and limitations of the method are discussed.     

A spectrophotometric method for the determination of nitrite

Nitrite reacts with dichromate quantitatively under suitable conditions of temperature and acid concentration. A linear relationship was found to exist between nitrite concentration and the absorbance at 580 nm of the chromium (III) species produced. This was used to determine the nitrite. The influence of a number of ions on the determination of nitrite was investigated; up to 100-fold excess nitrate has no influence on the determination of nitrite.     

A simple spectrophotometric method for the determination of minoxidil

A simple and sensitive method for the determination of minoxidil using 3-methyl-2-benzothiazolinone hydrazone (MBTH) and Fe(III) as the coloring agent is described. The method is sensitive to permit the determination of 0.5–4.5 μg ml⁻¹ of minoxidil at 500 nm. The accuracy and precision of the method were checked by high-performance liquid chromatography.     

A spectrophotometric method for the determination of nitric oxide

In dimethylsulfoxide, nitric oxide reduces copper(II) to copper(I) in the presence of p-chloroaniline. The resulting copper(I) is determined spectrophotometrically with 2,2′-biquinoline. The reactions are reproducible and the absorbance is proportional to the concentration of nitric oxide over the range 1.8–108 ppm (mg dm^?3. Most other atmospheric contaminants are without effect.     

A solid-phase spectrophotometric method for the determination of sulphathiazole

A spectrophotometric method for the determination of sulphathiazole (ST) has been developed, based on solid-phase spectrophotometry. The influence of experimental variables on fixation on Sephadex SP C-25 is discussed. The applicable concentration range is 0.10-10.00 mg/l., with a relative standard deviation of 0.62% and a detection limit of 0.02 mg/l. The accuracy and precision of the method are reported. The proposed method has been satisfactorily applied to the determination of sulphathiazole in pharmaceuticals.     

A new spectrophotometric method for the determination of nadolol

A new spectrophotometric method has been developed for the assay of nadolol in pure form and in tablets. The assay procedure is based on a derivatization methodology employing 4-carboxyl-2,6-dinitrobenzene diazonium ion (CDNBD) as a diazo coupling reagent. The azo dye formed between nadolol and CDNBD absorbed visible light at the wavelength maximum of 416 nm (λ_max) demonstrating a bathochromic shift from the absorption maximum of nadolol. Optimization studies established an optimal reaction time of 10 min at 60 °C. The assays were linear over 1.25–10 μg ml^?1 of nadolol, and the reaction occurred by a 3:1 reagent/drug stoichiometric ratio. The method is found to be selective and has a lower detection limit of 0.29 μg ml^?1. Recovery studies over three days gave mean recovery of 101.4% (RSD 3.0%). This new method has been successfully applied in the determination of nadolol and nadolol/bendroflumethiazide tablets with accuracy and precision similar to the official (USP) HPLC procedure (p > 0.05). The new procedure has the advantages of high sensitivity, lower limit of detection and could find application as an in-process quality control method for nadolol.     

A rapid spectrophotometric method for determination of piperazine

A spectrophotometric method has been developed for the determination of piperazine and its salts (citrate, phosphate, and tartrate) without prior separation, based on the interaction of piperazine or any of its salts with phenothiazine and N-bromosuccinimide in aqueous methanol. The products exhibit absorption maxima at 448, 595 and 645 nm. Measurements are made at 595 nm. Beer's law is obeyed in the concentration range 0.5-5 mug/ml for piperazine salts and 0.5-3 mug/ml for piperazine hexahydrate. The method is rapid, simple and successful for analysis of some pharmaceutical preparations.     

A simple spectrophotometric method for the determination of hydrazine salts by reaction with phosphomolybdic acid

Summary A Simple Spectrophotometric Method for the Determination of Hydrazine Salts by Reaction with Phosphomolybdic Acid A simple, rapid and sensitive Spectrophotometric procedure is described for ppm determination of hydrazine salts. It is based on reduction of phosphomolybdic acid and measurement of the molybdenum blue thus formed at 822 nm. When compared with other procedures, this method proved to be of comparable sensitivity and has less interferences. As low as 0.31 ppm was accurately determined; the relative error and the relative standard deviation did not exceed 0.94 and 1.73%, respectively.     

A new spectrophotometric method for the micro determination of sulfuric acid esters in sulfatide fractions

Summary A new micro method has been developed for measuring sulfatide fractions. Sulfuric acid ester absorption is measured at 8.02 m () by infrared spectrophotometry, compared with that of a standard sulfatide, and corrected for phosphorus. General problems in measuring sulfatides are noted; procedural details, control studies, advantages, and limitations of the present method are discussed.

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Zusammenfassung Eine neue Mikromethode für die Bestimmung von Sulfatidfraktionen wird beschrieben. Die Absorption der Schwefelsäureester wird im Infrarot bei 8,02 m gemessen, mit jener eines Sulfatidstandards verglichen und für Phosphor korrigiert. Allgemeine, mit der Bestimmung von Sulfatiden verbundene Probleme werden erwähnt; technische Einzelheiten, Kontroll-untersuchungen, Vorteile und Grenzen der beschriebenen Methode werden besprochen.

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Résumé Mise au point d'une nouvelle microméthode pour la détermination de fractions de sulfatides. L'absorption de l'ester sulfurique est mesurée à 8,02 m () par spectrophotométrie infra-rouge et comparée avec celle d'un sulfate standard puis corrigée du fait de la présence du phosphore. Les auteurs rappellent les problèmes généraux rencontrés dans la détermination des sulfatides. Les détails opératoires, les études de contrôle, les avantages et les limitations de la présente méthode sont d'autre part discutés.

     

A new spectrophotometric method for the determination of dimethyl formamide

Summary The spectrophotometric determination of dimethyl formamide comprises hydrolysation to dimethyl amine and reaction with carbon disulphide to dithiocarbamate, which gives a yellow complex (_max=430 nm) with copper(II). Standard deviation was ±0.0086 g/ml. There are no interferences from various copollutants.     

A general method for the spectrophotometric determination of aromatic aldehydes

Summary Aromatic aldehydes and some of their binary mixtures can be determined spectrophotometrically with diphenylamine in the presence of hydrochloric acid. Errors are in the range of 6–10%. Various other organic compounds do not interfere.

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Allgemeines Verfahren zur spektralphotometrischen Bestimmung aromatischer Aldehyde

Zusammenfassung Aromatische Aldehyde und einige ihrer binären Gemische können mit Diphenylamin in salzsaurer Lösung spektralphotometrisch bestimmt werden. Fehler sind im Bereich von 6–10%. Eine große Zahl anderer organischer Verbindungen stört nicht.

     

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.