Titrimetric and Spectrophotometric Determination of Catecholamines

Abstract

Catecholamines can be determined coulometrically at constant-current electrolysis of 30 milliamperes in concentration corresponding to 1×10^?9 to 1×10^?6 equivalents per second of electrolysis time. Iodine - reagent is generated electrically and its amount is evaluated from a knowledge of the current and the generating time. This procedure is compared with the potentiometric method using a redox electrode.     

Extraction and Spectrophotometric Determination of Diclofenac in Pharmaceuticals

A new simple, rapid and sensitive spectrophotometric method has been developed for the determination of diclofenac sodium (Dicl) in pharmaceutical preparations. This method is based on the reaction of diclofenac sodium with an analytical reagent 1,3,3‐trimethyl‐5‐thiocyanato‐2‐[3‐(1′,3′,3′‐trimethyl‐3′‐H‐indol‐2′‐ylidene)‐propenyl]‐indolium cloride (TIC) at pH 8.0‐11.0 and the extraction of ion associate colored complex. Optimal conditions for the complex formation between Dicl and TIC were studied. This ion associate complex (1:1) was detected and extracted with toluene and an absorption maximum at 566.2 nm against a blank reagent. The calibration graph was linear from 0.9‐11.0 μg/mL of diclofenac and the detection limit was 0.86 μg/mL.     

Spectrophotometric Determination of Saccharin in Soft Drinks and Pharmaceuticals

Abstract

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of saccharin using azure C. Saccharin reacts quantitatively with azure C in citric acid buffer forming a blue product. The blue product can be extracted into chloroform, Beer's law is valid over the concentration range 3–75 ppm of saccharin and the molar absorptivity is 3.1 × 10³ 1 mol^?1 cm^?1. Reasonable amounts of ingredients that are likely to be present in soft drinks and pharmaceuticals do not interfere. Recoveries of saccharin from soft drinks and pharmaceuticals were satisfactory.     

Flow-Injection Spectrophotometric Determination of Diclofenac or Mefenamic Acid in Pharmaceuticals

 Two flow injection (FI) spectrophotometric methods are proposed for the determination of diclofenac (DCF) or mefenamic acid (MF) in bulk samples and pharmaceuticals. Both methods are based on the reaction of DCF or MF with potassium ferricyanide in a sodium hydroxide medium. The absorbance of the orange products obtained is measured at 455 nm for DCF and 465 nm for MF. The corresponding calibration graphs are linear over the range 0.20–20.0 mg L⁻¹ for DCF and 1.00–100 mg L⁻¹ for MF, while the limits of detection were 0.05 and 0.18 mg L⁻¹, respectively. Received March 27, 2000. Revision November 15, 2000.     

分光光度法测定微乳液中脂肪酶的酶活

通过对胶束酶学对传统脂肪酶酶活测定的改进,建立了适合于油包水微乳液体系中脂肪酶酶活测定的分光光度方法。与传统方法相比,本法克服了底物乳化液难配制、不稳定等缺点,无需进行在pH缓冲溶液体系中的酸碱滴定,提高了酶活测定的准确性。     

Thin-Layer Chromatographic Selective and Stability-Indicating Method for Assay of Cefixime in Pharmaceuticals

JPC – Journal of Planar Chromatography – Modern TLC - A thin-layer chromatographic (TLC) method is developed for the analysis of cefixime using precoated silica gel 60F254 TLC aluminum...     

乙基曙红光度法测定西地那非的含量

在pH3.5～4.0的NaAc HCl缓冲介质中,西地那非与乙基曙红反应,形成离子缔合物,使乙基曙红溶液颜色发生明显改变,最大吸收波长在550nm,比乙基曙红红移了30nm,并在520nm处产生最大褪色作用,从而建立测定西地那非(Sild)的光度法。在最大褪色波长520nm处,西地那非浓度在0.2～2.0×10-5mol·L-1范围内遵守比耳定律,表观摩尔吸光系数ε520为2.44×104L·mol-1·cm-1,检出限为9.3×10-7mol·L-1,若用双波长叠加,则表观摩尔吸光系数ε520+550达4.53×104L·mol-1·cm-1,检出限达5.0×10-7mol·L-1。本法操作简便,体系稳定,灵敏度较高,选择性好,用于柠檬酸西地那非片(万艾可)中西地那非含量的测定,结果满意。     

Spectrophotometric Determination of Phenyxpropanolamine Hydrochloride in Pharmaceuticals after Derivatization with NBD-C1

Abstract

It is demonstrated that 7-chloro-4-nitrobenzo-2-oxa-l,3-diazole (NBD-C1) is a useful dérivatizing agent for the quantification of primary amine containing ingredients in pharmaceutical preparations by spectrophotometric analysis. Colorimetric assay is simpler and eliminates many technical difficulties encountered when employing NBD-C1 dérivat izat ion in fluorometric analysis. The methodology presented is rapid, accurate and free from interferents which accompany other analytical methods for the determination of phenylpropanolamine hydrochloride when in combination with other commonly compounded ingredients such as acetaminophen, caffeine and/or aspirin. Results are presented for the colorimetric method which compare favorably with other appropriate reference methods presented in the literature.     

Determination of Some Quinone Containing Drugs by Direct and Titrimetric First Derivative Spectrophotometric Methods

Abstract

The first-derivative spectra of some metal complexes of danthron and phanquone show well defined, prominent peaks. This can be made the basis of a spectrophotometric technique for the determination of both danthron and phanquone.

Two spectrophotometric. procedures are described. The first-derivative spectrophotometric technique, found to be more sensitive than the direct-absorbance method when the metal complex is weakly absorbing, can be applied to the determination of danthron, and phanquone both in pure form and in pharmaceutical formulations. Danthron can be determined in the range of 0.48–5.7 mg using metal complexes. Phanquone can be determined in the range of 0.42–2.08 mg using iron (II), and 3.78–11.34 mg using cobalt (II).

The second procedure is a first-derivative spectrophotometry titration for the determination of 0.096–0.57 mg of danthron and 0.048–1.0 mg of phanquone using the standard metal ion- solutions as titrants.     

Spectrophotometric Assay of Certain Aminoglycosides Using Cyanoacetamide

Abstract

A simple and sensitive ultraviolet spectrophotometric method has been devised for the determination of amikacin, kanamycin, neomycin and streptomycin in pure form and in some pharmaceutical preparations. The method depends on the nitrosation of the primary amino groups followed by reaction with cyanoacetamide in ammonia medium at 100°C for 30 min, The reaction products exhibit a characteristic absorption. maximum at 270 nm. Beer's law is obeyed within the concentration ranges 4–40 μg ml^?1 for amikacin, kanamycin and neomycin and 8–80 μg ml^?1 for streptomycin with apparent molar absorptivities of about 1.85 × 10⁴ for the first three compounds and 1.3×10⁴ 1. mole^?1.cm^?1 for streptomycin.     

Titrimetric and Spectrophotometric Determination of Some Phenothiazine Psychotropics in Pure Form and in Pharmaceutical Formulations with Metavanadate

 Two simple, fast, accurate and precise methods for the determination of six phenothiazines and a number of their pharmaceutical formulations are described. The titrimetric method involves the oxidation of the drugs by metavanadate in sulphuric acid medium and titration of vanadium(IV) formed, with cerium(IV) using ferroin indicator and acetone as catalyst. In spectrophotometry, vanadium(IV) formed was reacted with ferriin and the resulting ferroin measured at 510 nm. Phenothiazines in the ranges 5–100 mg and 2.5–25.0 μg mL⁻¹ can be determined by titrimetry and spectrophotometry, respectively, with detection limits of 0.96–2.05 mg and 0.0359–0.0565 μg mL⁻¹, respectively. Both methods were applied successfully to the determination of the studied drugs in pharmaceutical preparations. The reliability of the assays was established by parallel determination by the official methods of British Pharmacopoeia and the results being statistically evaluated. Received September 26, 2000. Revision March 25, 2001.     

First-Derivative Spectrophotometric Assay of Timolol Maleate in Ophthalmic Solutions

Abstract

This research reports the application of derivative spectrophotometry to the determination of timolol maleate in ophthalmic solutions. A systematic approach developed for optimisation of the derivative order, graphical measurements and instrumental conditions led to the adoption of first-order spectrophotometry as a method with suitable precision and selectivity for the determination of timolol maleate in ophthalmic solutions without previous treatment.     

Rapid Spectrophotometric Assay of Cephradine and its Dosage Forms

Abstract

A new spectrophotometric method to determine cephradine based on its reaction with acetylacetone-formaldehyde reagent (pH 4.3) is proposed. The yellow chromophore shows an absorption maxima at 400 nm, having a molar absorptivity coefficient of 2.59. 10³ L mol^?1 cm^?1. Optimization of the reaction conditions has been investigated. Obediance to Beer's law (0–110 mog per ml) permitted the assay of cephradine in its dosage forms. The method has been compared with the official method and found to be simple, artwrate (t-test) and reproducible (F-test).     

Determination of Sulfaguanidine in Food and Veterinary Pharmaceuticals by Flow Injection Analysis with Spectrophotometric Detection

This work proposes a flow injection analysis system for sulfaguanidine determination in pharmaceutical and food samples. The method was based on the reaction of sulfaguanidine with nitronium ion to produce a colored complex whose absorbance was measured at 545?nm. The flow injection analysis system’s significant parameters were checked by a fractional factorial design 2^7–2 and optimization by a Doehlert matrix. The flow injection analysis system shows optimum values at 0.28, 2.00, and 0.11% (w/v) for N-naphtil ethylenediamine, ammonium sulfamate, and sodium nitrite concentrations, respectively. The possible interferents present in pharmaceutical and food samples were assessed by a multivariate technique and depicted on probability charts, indicating no significant interferences at the 95% level of confidence interval. The method showed detection and quantification limits of 0.012 and 0.039?mg?L^?1, an analytical frequency of 30 readings h^?1 and precision always lower than 5.0% expressed as the relative standard deviation. The obtained results were in accordance with those obtained by high-performance liquid chromatography.     

Green Spectrophotometric Method for the Quantitative Analysis of Vancomycin in Pharmaceuticals and Comparison with HPLC

Abstract

A spectrophotometric method for the determination of vancomycin base, (VCM), and vancomycin hydrochloride, (HVCM), based on the reaction with copper (II) ions, is presented. The obtained detection limit is about 4.5×10^?5 mol L^?1. The working analytical range falls between 1.0×10^?3 mol L^?1 and 1.0×10^?2 mol L^?1. Recovery studies in presence of excipients were performed. The recovery results were compared with HPLC. For HVCM the proposed method presented similar recovery to that of HPLC, 100.4% vs. 100.2%, but better precision, 1.9% vs. 6.1%. In the VCM case the recovery is quite better, 100.5% vs. 89.6%, with a little smaller precision, 2.1% vs. 1.3%.     

Spectrophotometric Assay of Certain Aminoglycosoide Antibiotic Using Chloranil

Abstract

Chloranil (2,3,5,6-teterachloro-p-benzoquinone) reacts with certain aminoglycosoide antibiotics in borate buffer at pH 9.0 to give charge-transfer complexes. The complexes possese an absorption maxmum at about 350 nm with molar absorptivities of 3.78 × 10⁵, 4.69 × 10⁵, 5.0 × 10⁵ and 7.08 × 10⁵ for kanamycin, neomycin B, amikacin and tobramycin reepectively, These high intensity of the chargetransfor band and confirmity to beer's law enabled assay of these antibiotics with appreciable sensitivity and good precision.

Aminoglycosoide antibiotics have a broad spectrum of activity against both gram-negative and gram-positive bacteria.

The official compendia^1,2 recommend the microbiological assay for their evalution. The high experimental errors in microbiological estimation heae been reported³. Numerous spectrophotometric, fluorometric and chromatographic techniques for their quantitation have been thoroughly reviewed^4,5.

Substituted quinones such as 2,5 dichloroquinone⁶, 7,7,8,8-tetracyanoqulnone dimethane⁷, flouranil⁸ are used as TT- acceptors with various electron donors to form charge-transfer(CT) complexes and radical ions^9,10. Some aromatic amines^11,12 and aminoacids have been determined with chloranil^13–15.

The present work describes the utility of chloranil for the spectrophotometric determination of kanamycin sulphate, amikacin sulphate tobramycin aulphate, and neorycin B sulphate (framycetine sulphate) either in bulk or in their reepective doaage forms.     

Validated Assay for the Determination of Mitoxantrone in Pharmaceuticals Using Capillary Zone Electrophoresis

Abstract

The first capillary zone electrophoretic (CZE) method for the determination of mitoxantrone (MTX) in pharmaceutical formulations was developed. The influence of background electrolyte (BGE) species, pH, concentration (c _BGE), organic modifier, capillary temperature, applied voltage, and injection time was investigated. Optimum results were achieved with 25 mM ammonium acetate at an apparent pH value of 5.0 in 50% v/v acetonitrile, applied voltage of +30 kV, and capillary temperature of 25°C. The samples were introduced into the capillary hydrodynamically for 2 s at 33.5 mbar. Mitoxantrone was detected at a wavelength of 242 nm. Mitoxantrone and doxorubicin (DOX) (used as internal standard, ISTD) were completely separated in less than 7 min. The method was suitably validated with respect to linearity, limits of detection (LOD) and quantification (LOQ), accuracy, precision, selectivity, and robustness. The proposed method was applied successfully for the determination of MTX in its injectable pharmaceutical formulation.     

乘子法在多组分光度分析中的应用

报道了将乘子法用于样品中多组分的分光光度法同时测定;介绍了乘子法的原理和计算步骤。对复方新诺明模拟样中磺胺甲恶唑、甲氧苄氨嘧啶测定的平均回收率分别为９９．７９％,１００．６７％,ＲＳＤ分别为０．４５％．０．９５％（ｎ＝９）,测定了５个批号复方新诺明片剂和针剂的含量,结果满意。     

A Direct Spectrophotometric Assay for Pyruvic Oxime Hydrolase

Abstract

A sensitive spectrophotometric method, which directly measures the formation of pyruvic oxime from pyruvate and NH₂OH in the UV, is described for the detection of pyruvic oxime hydrolase activity in biochemical systems. The method was used in an attempt to detect pyruvic oxime hydrolase activity in cell-free extracts from an Alcaligenes sp. which can grow on pyruvic oxime. Although substantial pyruvic oxime + nitrite oxidative activity was detected in cells and cell-free extract of this bacterium, catalysis of pyruvic oxime formation was not observed within the error of the method (～20% of the uncatalyzed rate constant of 1.9x10^?3 s^?1 at pH 7, 22°C). The rate of pyruvic oxime oxidation by cells and cell-free extract was at least 10⁵?10⁶ times greater than the rate of its hydrolysis, thus implying that oxidation of pyruvic oxime need not require prior hydrolysis. The method would appear to be applicable to hydrolases directed toward a variety of oximes.     

Titrimetric and Spectrophotometric Methods for the Determination of Glyoxal and Analysis of Ternary Mixtures of Its Oxidation Products

Using thallium(III) as an oxidant, we developed titrimetric and spectrophotometric methods for the estimation of glyoxal at mmole and µmole levels, respectively. In the titrimetric method, thallium(I) formed is determined oxidimetrically with potassium bromate. In the spectrophotometric method, the absorbance of thallium(III) at 260 nm in the presence of 0.1 mol/L sodium chloride and 1.0 mol/L perchloric acid is measured. A plausible mechanism for the oxidation of glyoxal is proposed. Based on the selective oxidation of the probable oxidation products of glyoxal (namely, glyoxylic acid, formic acid, and oxalic acid), a convenient titrimetric method is described for analyzing ternary mixtures of these products.__________From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 8, 2005, pp. 806–810.Original English Text Copyright © 2005 by Siva Rao, Prasada Rao.The text was submitted by the authors in English.