Spectrophotometric determination of trazodone, amineptine and amitriptyline hydrochlorides through ion-pair formation using methyl orange and bromocresol green reagents

A simple and rapid extraction spectrophotometric procedure has been developed for the determination of tricyclic anti-depressant drugs such as trazodone (TZH), amineptine (APH) and amitriptyline (ATPH) hydrochlorides in pure form and in different dosage forms. The method involves the formation of intense yellow ion-pairs between these drugs under investigation and methyl orange (MO) and bromocresol green (BCG) reagents followed by their extraction with 1,2-dichloroethane and quantitative microdetermination at 420 and 410 nm using MO or BCG, respectively. The optimum experimental conditions for the ion-pairs formation are established. The method permits the determination of TZH, APH and ATPH over a concentration range of 2-50, 2-50 and 1-25 microg ml(-1) for TZH, APH and ATPH, using MO and 1-25 microg ml(-1) for TZH, APH and ATPH, using BCG, respectively. The Sandell sensitivity (S) is found to be 0.106, 0.1071 and 0.0907 g cm(-2) for TZH, APH and ATPH, respectively, using MO reagent and 0.0788, 0.0661 and 0.0494 g cm(-2) for TZH, APH and ATPH, respectively, using BCG. The method is applicable for the assay of the investigated drugs in different dosage forms and the results are in good agreement with those obtained by the official method.     

Spectrophotometric determination of chlorhexidine with bromocresol green by flow-injection and manual methods

A spectrophotometric study of the chlorhexidine/bromocresol green/Triton X-100 system is reported; at pH 5.3, both 2:1 and 1:1 bromocresol green/chlorhexidine complexes are formed. In the manual spectrophotometric method, Beer's law is obeyed for chlorhexidine concentrations of 2.9–32.2 μg ml^?1 (r.s.d. 0.4–1.3%); the molar absorptivity is 12 500 l mol^?1 cm^?1. In the flow-injection method, the calibration graph is linear for the chlorhexidine range 23.0–83.9 μg ml^?1 (r.s.d. 0.8%); the injection is ca. 60 h^?1. Benzocaine, acetylsalicylic acid, ascorbic acid and sucrose are tolerated at 10^?2?10^?3 M levels. Hibitane 5% was analyzed successfully.     

Rapid titrimetric determination of thorium with fluoride using SPADNS

Summary A rapid titrimetric method for the estimation of thorium in the range from 5 to 88 mg. in a 50 ml. of final volume has been developed which involves the adjustment of P_h at 3.0, addition of 2 ml. of 0.02% SPADNS indicator, dilution to volume and titration with standard NaF until the colour obtained matches a blank containing the buffered solution of the indicator alone. The method has been standardised against known amounts of thorium and a calibration curve relating the titre of the fluoride solution to thorium content has been prepared. Interferences of various cations and anions have also been studied. From the results, the quantitative nature of zirconium interference has been confirmed. The method for the determination of thorium is very rapid and the colour change being sharp from blue-violet to scarlet-red, the detection of endpoint is not at all difficult.The author wishes to thank Dr. A. K. Ghosal, Principal, Darjeeling Government College, for providing Laboratory facilities and Prof. P. Ray and Dr. A. K. Mukherjee of the Indian Association for the Cultivation of Science, Calcutta for their encouragement in the research work.     

Spectrophotometric determination of vanadium and niobium: Xylenol orange as a chromogenic reagent

Summary The formation of red coloured chelates of vanadium(V) and niobium(V) with xylenol orange (DCAC) having _max at 490 nm (at p_H 5.0) and 530 nm (at p_H 5.5) have been reported. The colour formation has been applied to the spectrophotometric determination of metal ions. The colour has been found to be stable between p_H 3.5–6.5 and 2.0–7.0 respectively. The sensitivity of the reagent is 0.051g/cm² of vanadium and 0.093g/cm² of niobium. Maximum colour intensity has been found for Nb-DCAC chelate at p_H 5.5 whereas no appreciable change has been found for V-DCAC chelate between p_H 4.5 and 6.5.

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Zusammenfassung Über die Bildung rot gefärbter Chelate von Vanadin und Niob mit Xylenolorange wurde berichtet. Deren Absorptionsmaxima liegen bei 490 nm (p_H 5,0) bzw. bei 530 nm (p_H 5,5). Die Farbreaktion wurde für die Bestimmung der beiden Metalle verwendet. Die Farbe ist zwischen p_H 3,5 und 6,5 bzw. zwischen p_H 2,0 und 7,0 stabil. Die Empfindlichkeit für Vanadin beträgt 0,051g/cm², für Niob 0,093g/cm². Die Farbe des Niobchelates erreicht bei p_H 5,5 ein Maximum, während die des Vanadinchelates zwischen p_H 4,5 und 6,5 keine wesentlichen Änderungen erkennen läßt.

     

Successive complexometric determination of thorium and uranium in sulphuric acid media

A selective analytical extraction method for rapid successive complexometric determination of thorium(IV) and uranium(VI) in sulphuric acid media is described. The method is based on the extraction of thorium and uranium from sulphuric acid media with N-butylaniline or N-benzylaniline in chloroform. Both thorium and uranium are selectively and quantitatively extracted in the presence of ascorbic acid and EDTA. Most cations and anions do not interfere. The reduction of uranium(VI) with sodium dithionite at room temperature is rapid and quantitative and superior to that with ascorbic acid, which reduces uranium(VI) in boiling solution. The method is simple, rapid and accurate, and the experimental conditions are not highly critical.     

A note on successive complexometric determination of thorium and rare earths

An improved method for successive determination of thorium and rare earths is described. It is based on the EDTA titration of thorium at pH 2 (Xylenol Orange as indicator) followed by addition of acetylacetone-acetone mixture, adjustment of the pH to 5-5.5 with hexamine, and by further EDTA titration of rare earths with the same indicator.     

Direct complexometric titration of thorium with versene using SPADNS

Summary The existing volumetric methods for the determination of thorium are indirect and unsatisfactory. A direct titrimetric method for the estimation of thorium has been developed which involves the adjustment ofph, addition of 1 ml. of 0.02% SPADNS indicator, dilution to volume and titration with versene. It is based on the fact that thorium forms a coloured complex with SPADNS and after the bulk of thorium has reacted with versene, the highly coloured thorium- indicator complex is destroyed, marking the end point. Quantity of thorium as small as 5 mg. can be titrated accurately when present in a volume of 50 ml. Determination of thorium can also be made in presence of large amount of iron by adding ascorbic acid prior to the titration. Interferences of various ions have also been studied. The method proposed for thorium is selective and should be of considerable use in many cases.The author's thanks are due to Dr. A. K. Ghosal, Principal Darjeeling Government College, for providing all laboratory facilities and Dr. A. K. Mukherjee, Indian Association for the Cultivation of Science, Calcutta for his kind help in the work.     

Spectrophotometric method for the determination of demeclocycline using sodium molybdate as analytical reagent

By means of spectroscopic methods it has been found that demeclocycline reacts with molybdate ions forming a complex compound [MoO₃HDMTC]^2–. The relative stability constant of this compound has been determined by applying spectrophotometric methods. Under optimum conditions for complex formation a very sensitive spectrophotometric method for the estimation of demeclocycline in the concentration range 5.0–35.1 g/ml is proposed. The detection limit of the method is 2.5 g/ml of demeclocycline. The relative standard deviation (n=10) varies between 0.76% and 1.46%. The method proved to be accurate and sensitive for the analysis of the demeclocycline content in tablets.     

Spectrophotometric determination of silicon in thorium oxide

A method is described for the spcctrophotometric determination of microgram quantities of silicon in the presence of thorium. Thorium oxide is dissolved by heating it at 70 to 8o°C in 4M HNO₃ that contains 2 drops of HF. Under these conditions, no silicon is lost through volatilization. The silicon is estimated as the blue ailicomolybdate complex. Under the conditions selected for development of color, a precipitate of thorium molybdate is obtained ; the thorium molybdate is, however, dissolved without affecting the color of the complex by the addition of tartrate and adjusting the pH of the solution to 3.0. The lower limit of detection is about 5 p.p.m. of silicon.     

Spectrophotometric determination of methylamine moiety containing pesticides using ninhydrine reagent

A spectrophotometric method has been proposed for the determination of pesticides containing methylamine moiety. These pesticides afforded methylamine upon alkaline hydrolysis, which was subsequently reacted with ninhydrin in the presence of pyridine. The absorbance of the resulting blue-purple product was measured spectrophotometrically at 570 nm. The Beer??s law showed a linear relationship between absorbance and concentration of the pesticide in the range 0.04?C5.0 ??g/mL. The limit of detection and limit of quantification were 0.012 and 0.02 ??g/mL, respectively. The repeatability was 0.22 expressed as RSD. The performance of this newly developed method was compared with the established spectrophotometric methods for the determination of these pesticides. The method has been successfully applied to the evaluation of these pesticides in commercial pesticide formulation and to the determination of monocrotophos in fruit samples.     

Spectrophotometric determination of thorium(IV) using 3-nitroso-4-hydroxycoumarin

Summary 3-Nitroso-4-hydroxycoumarin is suggested as a new reagent for the spectrophotometric determination of 125 g to 0.50 mg Th(IV) in 3: 1 dioxan: water medium as 1: 1 complex having orange red colour with absorption maximum at 419 nm, at pH 4.5–6.0. For the estimation of9.6 ppm Th(IV) 100-folds acetate, citrate, tartrate; 50 ppm UO₂ ²⁺, 75 ppm Ce³⁺, La³⁺, Gd³⁺; 4.5 ppm Ce⁴⁺; 25 ppm Tm³⁺, Zr⁴⁺; and 100 ppm Ti⁴⁺, V⁵⁺, MoO₄ ^2– and WO₄ ^2– do not interfere.

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Zusammenfassung 3-Nitroso-4-hydroxycoumarin wird als neues Reagens für die spektrophotometrische Bestimmung von 125 g bis 0,50 mg Th(IV) in Dioxan: Wasser = 3: 1 als 1: 1-Komplex mit orange-roter Farbe mit einem Absorptionsmaximum bei 419 nm bei pH 4,5–6,0 empfohlen. Bei einem Einsatz von 9,6 ppm Th(IV) stört die hundertfache Menge Acetat, Citrat, Tartrat nicht. Auch 50 ppm UO₂ ²⁺, 75 ppm Ce³⁺, La³⁺, Gd³⁺, 4,5 ppm Ce⁴⁺, 25 ppm Tm³⁺, Zr⁴⁺, 100 ppm Ti⁴⁺, V⁵⁺, MoO₄ ^2– bzw. WO₄ ^2– stören nicht.

     

用聚合表面活性剂作增敏试剂分光光度测定钼和钨

采用表面活性剂的分光光度分析法应用日趋广泛。这方面的研究工作虽极活跃,但较多工作限于已有经典表面活性剂的研究与应用,为分析化学的特定需要设计与合成新型表面活性剂的研究尚少。作者曾用环氧氯丙烷和长链烷基叔胺合成了以聚乙二醇为主链含有若干个带长链烷基的季氮支链的低聚合表面活性剂——聚(氧化丙烯)-α-十八烷基二甲基氯化铵(PPOSA)。实验表明,这类表面活性剂兼有阳离子和非离子表面活性剂的某些特性。本文     

Spectrophotometric determination of uranium using ascorbic acid as a chromogenic reagent

A spectrophotometric method has been developed for the determination of uranium(VI) using ascorbic acid. Uranium in the hexavalent state forms a reddish-brown coloured complex with ascorbic acid. The colour intensity of the complex is maximum at pH 4.2-4.5 and is stable for 24 hr. The absorbances of uranium(VI)-ascorbic acid complex at 360 and 450 nm are used for its quantification. Uranium in the range 8-200 microg/ml has been determined with good precision. The method allows the determination of uranium in the presence of many metal ions present as impurities. The described method is simple, accurate and applicable to uranium concentration relevant to the PUREX process and thus can be used for analytical control purposes.     

Spectrophotometric methods for the determination of manganese

A comprehensive and critical review of the available spectrophotometric methods for the determination of manganese is presented. Details are given of a wide range of direct colour-forming reactions of manganese with organic ligands, which have been claimed to be of use in analysis for the metal. The use of the very sensitive kinetic methods of analysis is also discussed. It is found that there is a paucity of reliable detail concerning the general applicability of most methods to manganese determination and that there is even less detail on the comparative value of different methods for determination of the metal in particular types of matrix.     

Spectrophotometric methods for the determination of tolnaftate

Two simple and sensitive visible spectrophotometric methods (methods A and B) for the determination of tolnaftate in bulk samples and formulations are described. Method A (lambda(max) 490 nm) involves the reaction of tolnaftate with 2,6-dichloroquinone-4-chlorimide (DCQC: Gibb's reagent), while method B (lambda(max) 530 nm) is based on a similar reaction of the drug with p-N,N-dimethylphenylene diamine in the presence of chloramine-T. Both these methods are applicable to pure samples as well as formulations of the drug.     

Selective complexometric determination of mercury with sulphite as indirect masking reagent

A complexo-titrimetric method for the determination of mercury(II) in the presence of other metal ions is described, based on the selective masking ability of sulphite ion towards Hg(II). Mercury in a given sample solution is initially complexed with a known excess of EDTA and the surplus EDTA titrated with zinc sulphate solution at pH 5.0–6.0 (hexamine), using xylenol orange (or methylthymol blue) as indicator. An excess of solid sodium sulphite is then added to decompose the Hg(II)-EDTA complex and the released EDTA is titrated with standard zinc sulphate solution. Reproducible and accurate results are obtained for 9.9–99 mg Hg with relative errors < 0.35% and standard deviations < 0.05 mg. The effects of various cations and anions are studied.     

Indirect complexometric determination of palladium(II) using sodium nitrite as a selective masking reagent

A selective complexometric method is described for the determination of palladium, sodium nitrite being used as masking reagent. Palladium(II) in a given sample solution is initially cornplexed with an excess of EDTA and the surplus EDTA is titrated with zinc sulfate solution at pH 4.5–5.5 (acetic acid-sodium acetate buffer), using xylenol orange as indicator. An excess of sodium nitrite is then added, the mixture is shaken well and the EDTA released from the Pd-EDTA complex is titrated with a standard zinc sulfate solution. Results are obtained for 2.5–27.5 mg of Pd with relative errors 0.5% and standard deviations 0.05 mg. The interferences of various ions are studied. The method is applied for the determination of palladium(II) in alloys and complexes.