氯冉酸可见分光光度法快速测定酮康唑

建立了快速测定酮康唑含量的可见分光光度法。实验结果表明:酮康唑与氯冉酸在甲醇-丙酮混合溶剂中发生电荷转移反应,产物的最大吸收波长是524 nm,表观摩尔吸光系数为1.04×103L·mol-1·cm-1。酮康唑质量浓度在20～400 mg·L-1范围内服从比耳定律,相关系数为0.9995。当酮康唑浓度为200 mg·L-1时,五次测定结果的相对标准偏差为1.03%。测得荷移络合物的组成比和稳定常数分别为1∶1和3.9×103。回收率在98.0%以上。本方法简便、快速、准确,可作为制剂的质量控制方法。     

Differential spectrophotometric determination of tartrate with chloranilic acid

A differential spectrophotometric method for the determination of tartrate using chloranilic acid is described. Standard and sample solutions containing slightly more tartrate than the reference solution, are measured relative to it. The procedure is applicable to the determination of tartrate in baking powder; the results obtained compared favorably with the official A.O.A.C. method.     

Spectrophotometric determination of atropine, pilocarpine and strychnine with chloranilic acid

In dioxan-chloroform medium the acceptor chloranilic acid forms 1:1 molecular complexes with the alkaloids atropine, pilocarpine and strychnine, with maximum absorption at 535, 527.5 and 535 nm respectively. Conformity with Beer's law allows the use of the complexes for the assay of these drugs.     

Adsorptive stripping voltammetric determination of vanadium as chloranilic acid complex

Traces of vanadium(V) can be determined up to 21 ng/l by adsorptive stripping voltammetry using 2,5-dichloro-1,4-dihydroxy-3,6-benzoquinone (chloranilic acid) as complex forming reagent. The complex is stable in a 0.1 mol/l acetate buffer (pH 4.6) solution and adsorbed at the electrode surface in a potential range between –150 mV and –400 mV. The adsorption process is solved by alternating current (ac) voltammetric measurements. The method is applied to different real samples.     

水与氯冉酸的荷移反应及其分析应用

用分光光度法研究了氯冉酸与水的荷移反应, 探讨了反应机理, 确定了反应条件. 氯冉酸与水形成紫色络合物的最大吸收波长为530 nm. 水量在0.13%～6%范围内呈线性关系, 检出限为体积分数0.13%, 相对标准偏差小于2%. 用本法测定乙醇、面粉及香料中的微量水, 与标准方法测定值相符, 回收率为97%～102%.     

Spectrophotometric determination of metronidazole and tinidazole via charge transfer complexation using chloranilic acid

A new spectrophotometric method was developed for the determination of two important nitroimidazoles; metronidazole (MZ) and tinidazole (TZ). The method was based on the charge-transfer (CT) complexation reaction of reduced forms of metronidazole and tinidazole as n-electron donors and chloranilic acid (CAA) as π-electron acceptor to form a purple-colored complex with a new absorption band at 520 nm which was adopted as the analytical wavelength. Molar absorptivities of 2.741 × 10² L M^?1 cm^-1 and 2.681 × 10² L M^?1 cm^?1 were obtained for MZ and TZ, respectively. Optimization of reducing agent and time of reduction revealed the superiority of metal hydrides over reducing metals. Reduction of MZ and TZ was completed at 30 °C within 10 min. Optimizations of temperature and time for the complexation reaction revealed that the reaction was completed at 30 °C within 5 min. A 60:40 mixture of 1,4-dioxane:acetonitrile was found to be the best diluting solvent for optimal detector response. The complexes were stable at room temperatures for weeks. Beer’s law was observed in the concentration of 5–40 ?g ml (MZ) and 4.8–79.2 ?g ml^?1 (TZ) with low limits of detection of 1.88 and 0.74 ?g ml^?1, respectively. Overall recoveries of MZ and TZ from quality control samples were 103.19 ± 2.05 (%RSD = 1.99, n = 12) and 101.63 ± 1.41 (%RSD = 1.39) over three days. There was no interference from commonly utilized tablet excipients. No significant difference existed between the results of the new method and the BP titrimetric procedures (p > 0.05). The new CT procedure described in this paper is simple, fast, convenient, accurate and precise and has the novelty of carrying out the reactions at room temperature compared to previously described procedures. The new method could be adopted as an alternative procedure for the quality assessment of MZ and TZ in bulk and dosage forms.     

Indirect spectrophotometric determination of ascorbic acid with ferrozine by flow-injection analysis

A FIA indirect spectrophotometric determination of ascorbic acid was developed using its reducing action on Fe(III) in acidic medium and following the spectrophotometric determination of the reduced iron by using sodium 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine-4',4'-disulphonate (ferrozine) as chromogenic reagent in buffered medium (pH 5.5) and monitoring the absorbance signal at 562 nm. A three-line manifold with two reaction coils was used: in the first reaction coil, ascorbic acid reduces Fe(III) to Fe(II); and in the second one, the complexation reaction is developed. The linear range of the method was 0.5-10 mug ml(-1) of ascorbic acid, the detection limit being 0.028 mug ml(-1). The proposed method was sensitive, rapid (sampling rate of 90 samples h(-1)) and reproducible (RSD 0.19%, n=10). Satisfactory results were obtained in the determination of ascorbic acid in pharmaceutical preparations, fruit juices and urine testifying the applicability of the method to real samples.     

Indirect determination of ascorbic acid by solid-phase spectrophotometry

Solid-phase spectrophotometry (SPS) technique, in the visible region, was used for the spectrophotometric determination of ascorbic acid based on the reducing effect on iron(III) ion, followed by formation of the iron(II)-ferrozine chelate. The chelate is easily sorbed on a dextran-type anion-exchange gel and the absorbance of the resin at 567 and 800 nm, packed in a 1 mm cell, is measured directly. The apparent molar absorptivity using 100 ml of sample was 2.1×10⁷ l mol⁻¹ cm⁻¹ and it allowed the determination of ascorbic acid in the range 5–90 ng ml⁻¹; the detection limit was 0.91 ng ml⁻¹ and the RSD 0.91% for a concentration of 50 ng ml⁻¹ of ascorbic acid (n=10). The proposed method permits a highly sensitive and selective determination of ascorbic acid without any preconcentration and it has been satisfactorily applied for its determination in fruit juices, pharmaceuticals, urine and conservative liquids.     

Analysis of insoluble silicate: Decomposition with molten sodium hydroxide and determination of Zr(IV) with chloranilic acid in medium-strong acid

Summary A rapid, accurate and precise method for the determination of zirconium in silicates is proposed. Insoluble or sparingly soluble samples are decomposed by means of molten sodium hydroxide. Chloranilic acid is employed as reagent for the spectrophotometric determination of Zr(IV). The limit of detection is 1.2×10^–7 M and the relative standard deviation is 0.24%.

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Analyse natürlicher Silicate: Aufschluß mit geschmolzenem Natriumhydroxid und Bestimmung von Zr(IV) mit Chloranilsäure in mittelstark saurer Lösung

Zusammenfassung Eine schnelle, genaue und präzise Methode für die Analyse von Zirkonium in Silicaten wird vorgestellt. Der Aufschluß von Zirkoniumsilicat mit geschmolzenem Alkalihydroxid ist für schwerlösliche Proben besonders geeignet. Die spektralphotometrische Bestimmung von Zirkonium mit Chloranilsäure (2,5-Dichlor-3,6-dihydroxy-1,4-benzochinon) zeigt, daß diese Methode sehr empfindlich und selektiv ist (Nachweisgrenze 1,2 · 10^–7 M, Standardabweichung 0,24%).

     

Determination of phenothiazines by charge-transfer complex formation with chloranilic acid

A rapid and sensitive spectrophotometrc method has been developed for the microdetermination of some phenothiazine derivatives as the pure substances and in different dosage forms. The method depends on the formation of stable donor-acceptor complexes between phenothiazines and chloranilic acid in an acetonitrile-2-propanol solvent mixture. The resulting intensely purple chloranilic acid radical anion possesses a characteristic absorption maximum at 515 nm. Beer's law is obeyed over the concentration ranges 1-6, 1-10 and 5-30 mug ml for prochlorperazine dimaleate, trifluoperazine dihydrochloride and thiethylperazine dihydrochloride, with apparent molar absorptivities of 7.76 x 10(4), 1.95 x 10(4) and 6.64 x 10(3) 1. mole(-1).cm(-1), respectively. Statistical comparison of the results with those of an official method shows excellent agreement and indicates no significant difference in precision.     

在NaNO3存在下浮选CuSCN间接测定抗坏血酸

建立了浮选CuSCN间接测定抗坏血酸(Vc)的方法。研究表明,在NaNO3存在下,Cu(Ⅱ)被抗坏血酸还原生成的Cu(Ⅰ)与SCN-形成CuSCN沉淀而被浮选。结果表明,Vc量在2.64~15.8 mg/L范围内与CuSCN的浮选率呈良好的线性关系,回归方程为:E/%=6.008ρ-3.673,r=0.9962。此方法可用于水果和药片中Vc量测定。     

The use of chloranilic acid salts in micro analysis

Summary The use of chloranilic acid salts is recommended for the micro determination of aluminium salts, sulphides, thiosulphates, cyanides and fluorides. The methods are based on the reaction of an insoluble chloranilate with the ion to be determined to form an insoluble compound of this ion and an equivalent of liberated chloranilic acid which can be measured. The procedures are simple and rapid.

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Zusammenfassung Zur Mikrobestimmung von Aluminiumsalzen, Sulfiden, Thiosulfaten, Cyaniden und Fluoriden wird die Verwendung von Salzen der Chloranilsäure empfohlen. Die Methoden beruhen auf der Reaktion unlöslicher Chloranilate mit dem zu bestimmenden Ion unter Bildung einer unlöslichen Verbindung dieses Ions und Freisetzung einer äquivalenten Menge Chloranilsäure, die gemessen wird. Die Bestimmungen lassen sich einfach und schnell durchführen.

     

萃取催化光度法间接测定痕量抗坏血酸

研究了在pH5.5的HAc NaAc缓冲溶液介质中,利用抗坏血酸活化Fe(Ⅲ)催化H2O2氧化邻氨基酚的显色反应,用萃取平衡控制反应时间和水相中邻氨基酚的浓度及反应程度,通过测量424nm下有机相的吸光度,建立了萃取催化光度法间接测定痕量抗坏血酸的新方法。方法的线性范围为0～50.0μg/L,检出限为6.7×10-7g/L。方法可用于维生素C片和西红柿中抗坏血酸的测定。并对反应机理进行了探讨。     

Spectrophotometric determination of phosphate by extraction of reduced molybdoantimonylphosphoric acid with acetophenone-chloroform

A 90% ($\text{v}\text{v}$) mixture of acetophenone-chloroform is an effective extractant for reduced molybdoantimonylphosphoric acid. The extraction is quantitative over the acidity range of 0.04 to 4.8 N sulfuric acid. The mixed solvent extractant is virtually immiscible with water and can be used at aqueous/organic volume ratios from 1:1 to 40:1 with no loss of solvent or decrease in % extraction. Phosphate is easily determined from 5 to 1000 ppb. No interference from silicate was experienced.     

The use of chloranilic acid salts in micro analysis

Summary A quick method for the determination of polymetaphosphates, orthophosphates, pyrophosphates and their mixtures with the help of chloranilic acid salts has been described.By measuring the optical density on a spectrophotometer at 505 nm the following quantities per ml can be determined approximately: polymetaphosphate, orthophosphate and pyrophosphate, 0.05 mg; polymetaphosphates in the presence of orthophosphates, 0.15 mg.

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Zusammenfassung Es wird ein Verfahren zur raschen spektrophotometrischen Bestimmung von Polymetaphosphaten, Orthophosphaten und Pyrophosphaten sowie ihren Gemischen mit Hilfe von Chloranilsäure beschrieben. Hierbei wird die optische Dichte bei 505 nm gemessen. Es können noch 0,05 mg Phosphat/ml bestimmt werden (bei Polymetaphosphat in Gegenwart von Orthophosphat: 0,15 mg/ml).

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Part I: Hoffmann, E.: Z. analyt. Chem. 185, 372 (1962)     

Chromium,molybdenum and ruthenium complexes of chloranilic acid

Chloranilic acid (H₂CA) reacts with Cr(CO)₆ and CrCl₃ to give the tris derivatives Cr(H₂CA)₃ and Cr(HCA)₃. Spectroscopic measurements on the two complexes reveal that the ligand–metal bond is of the semiquinone type. Susceptibility determinations showed effective magnetic moments of 1.82 and 1.07_B. Examination of Cr(H₂CA)₃ by cyclic voltammetry revealed two redox reactions due to tautomeric interconversion through electron transfer. Boiling Mo(CO)₆ with H₂CA in air gave MoO₃(HCA) in which the molybdenum atom is in the +5 oxidation state. The i.r. spectrum of the MoO₃(HCA) displayed bands due to terminal M=O bonds. The cluster compound Ru₃(CO)₁₂ reacted with H₂CA to give Ru₃(CO)₁₀(-H)(HCA), the i.r. spectrum of which revealed that the ligand is bound to the metal as a catechol moiety. The spectroscopic and magnetic studies of the molybdenum and ruthenium complexes confirmed the proposed structures.