Determination of Ternary Mixtures of Vitamins by Ratio-Spectra Zero-Crossing Derivative Spectrophotometry

Abstract

The ratio-spectra zero-crossing first and third derivative spectrophotometry have been used for determining ternary mixtures of Vitamin 86, Vitamin B1 and Vitamin B12. The procedures are accurate, nondestructive and do not require solving of equations.

In both methods, calibration graphs are linear, with zero-intercept, up to 48 μg/ml of Vitamin B6, 64 μg/ml of Vitamin B1 and 60 μg/ml of Vitamin B12. Correlation coefficients range from 0.9999 to 1.0000.

Working wavelengths, 311, 272.5 and 215.5 nm, respectively, in the 1st-derivative mode and 300.5, 271.5 and 365 nm in the 3rd-derivative mode. Detection limits for each drug at p=0.01 level of significance were calculated to be 0.002, 0.009 and 0.004 μg/ml and 0.002, 0.004 and 0.001 μg/ml, in the first and third-derivative methods, respectively. Both methods apply favourably to either synthetic mixtures or commercial injections for these drugs.

An exhaustive statistical treatment of the experimental findings was performed to confirm the validity of the methods.     

Selective Differential Spectrophotometric Methods for Determination of Niclosamide and Drotaverine Hydrochloride

ABSTRACT

Differential (ΔA), second derivative (ΔD²) and third derivative (ΔD³) differential ultraviolet spectrophotometric methods have been presented for the quantitation of niclosamide and drotaverine hydrochloride in pure forms and in their pharmaceutical formulations. For niclosamide, the method is based on measuring ΔΔ A, Δ ΔD², A ΔD³ of niclosamide in alkaline solutions against their neutral ethanolic solutions as blanks. For drotaverine hydrochloride, the acidic solutions of the drug are measured against their alkaline solutions as blanks. The proposed methods are sensitive, highly specific and advangageous over the conventional UV assays, since the interference of the excipients, impurities, degradation products or other accompanying drugs is nullified. Accuracy of the analysis with the proposed procedures is significantly greater than the classical spectrophotometric methods.     

Spectrophotometric Assay of Certain Cephalosporins Based on Formation of Ethylene Blue

Abstract

The hydrolytic degradation of antibiotics is very often used as a preliminary step in the analytical procedures for their determination. Therefore, a procedure was developed for measuring small amounts of cefadroxil and cefotaxime in pure samples as well as in formulations.

The method depends on forming a vis-absorbing compound with N,N-diethyl-p-phenylenediamine sulphate (N,N-DPPD) (ethylene blue dye), after the hydrolysis of cefadroxil and cefotaxime in sodium hydroxide solution to give hydrogen sulphide. The method is selective for cephalosporins, since other β-lactam compounds such as penicillins do not give hydrogen sulphide under alkaline hydrolysis. Variables such as pH, temperature, reagent concentrations and stability of the colour produced have been evaluated to permit selection of the most advantageous technique. Beer's law obeyed over the concentration range 0.5–10 μg/ml and 0.5–7 μg/ml for cefadroxil and cefotaxime, respectively. The detection limit being 0.1 μg/ml and 0.05 μg/ml (defined as the amount of the drug that gave a signal of twice the background noise) for cefadroxil and cefotaxime, respectively. The method has been successfully applied to the analysis of some pharmaceutical formulations.

The results have been statistically compared with those obtained by the official method. The relative standard deviation (for 10 replicates) was 1.12 (9 μg/ml) and 0.49% (5 μg/ml) for cefadroxil and cefotaxime, respectively. Procedural details and data for the effect of operating parameters are presented.     

Absorption Spectra of 4f Electron Transitions of Neodymium and Erbium with 8-Hydroxyquinoline-5-sulphonic Acid and Diethylamine Systems and Its Analytical Application

Abstract

In this paper the absorption spectra of 4f electron transitions of the systems of neodymium and erbium with 8-hydroxyquino-line-5-sulphonic acid and diethylamine have been studied by normal and third-derivative spectrophotometry. Their molar absorptivities are 80 l.mol^?1.cm^?1 for neodymium and 65 l.mol^?1.cm^?1 for erbium. Use of the third-derivative spectra, eliminates the interference by other rare earths and increases the sensitivity for Nd and Er. The derivative molar absorptivities are 390 1.mol^?1.cm^?1 for Nd and 367 1.mol^?1.cm^?1 for Er. The calibration graphs were linear up to 11.8 μg/ml of Nd and 12.3 μg/ml of Er, respectively. The relative standard deviations evaluated from eleven independent determinations of 7.2 μg/ml (for Nd) and 8.3 μg/ml (for Er) are 1.3% and 1.4%, respectively. The detection limits (signal to noise ratio = 2) are 0.2 μg/ml for Nd and 0.3 μg/ml for Er. The method has been developed for determining those two elements in mixture of lanthanides by means of the third-derivative spectra and the analytical results obtained are satisfactory.     

Use of Derivative Spectrophotometry for the in Vitro determination of Phenylbutazone and Oxyphenbutazone in Human Plasma

Abstract

Fourth derivative-difference (ΔD₄.) spectrophoto metry is presented for the simultaneous assay of phenylbutazone and oxyphenbutazone as metabolites of bumadizone either in laboratory made mixtures or in human plasma. Phenylbutazone and oxyphenbutazone are determined through the measurement of ΔD₄ signals at 293 and 282 nm, respectively. The linear relationship of these values versus concentration of both compoundsin the range 1–5 μg/ml for phenylbutazone and 3–8 μg/ml for oxyphenbutazone permits their determination with high accuracy and good reproducibility. The relative standard deviation is less than 1.35% The proposed method could be used for monitoring bumadizone metabolites.     

Utility of p-chloranilic Acid and 2,3 Dichloro-5,6-dicyano p-Benzoquinone (DDQ) for the Spectrophotometric Determination of Triamterene

Abstract

Two simple and sensitive spectrophotometric procedures are suggested for analysis of triamterene. The first procedure is based on the reaction of triamterene with p-chloranilic acid (p-CA) in methylene chloride to form a highly stable coloured product, exhibiting maximum absorbance at λ 530 nm. Beer's law is obeyed in the range of 40–220 μg.ml^?1 with a mean percentage accuracy of 99.98 ± 0.446. Limit of determination is 20 μg.ml^?1. In the second procedure, the drug is determined via charge transfer complex formation with 2,3 dichloro-5,6-dicyano p-benzoquinone (DDQ) using methylene chloride as a solvent. Here the reaction product has two well defined maxima at 460 nm and 530 nm where each has been utilized for quantitative determination. Beer's law is obeyed in concentration ranges of 25–125 μg.ml^?1 and 25–150 μg.ml^?1 with mean percentage accuracies of 99.92 ± 0.449 and 100.00 ± 0.511 for both maxima. 460 and 530 nm. respectively. Limit of determination is 12.5 μg.ml^?1 at both maxima. Optimum conditions for each procedure have been studied and the stoichiometry of both reactions was ascertained using Job's method of continuous variation. The validity of the suggested procedures was assessed by applying the standard addition technique using the drug capsules. Both procedures are statistically analyzed as compared with BP method for analysis of triamterene (non aqueous titration) revealing good accuracy and precision as indicated by t and F tests.     

Spectrophotometric Determination of Gadolinium(III) With O-Hydroxyhydroqoinonephthalein in Mixed Micelles of N-Hexadecylpyridinilm Chloride and Brij 35

Abstract

A sensitive, simple and selective spectrophotometric method for the determination of gadolinium(III) is proposed using o-hydroxyhydroquinonephthalein(Qnph), by analogy with phenylfl-uorone(Phfl), in the presence of N-hexadecylpyridinium chlo-ride(HPC)-Brij 35 mixed surfactants. The calibration curve is rectilinear in the range of 0 – 16.0 μg per 10 ml at 590 nm with an apparent absorption coefficient(?) of 1.2 × 10⁵ 1 cm^?1 mol^?1 and Sandell sensitivity of 0.0013 μg/cm² gado-linium(III).     

The Simultaneous Determination of Δ9-Tetrahydrocanna-Binol and 11-Hydroxy -Δ9 -Tetrahydrocannabinol in Plasma

Abstract

A technique capable of determining both Δ⁹-tetrahydrocannabinol and 11-hydroxy-Δ⁹-tetrahydrocannabinol is described. The method is based on the reactivity of the phenolic functionality common to both compounds, and is sensitive to 5 ng of Δ⁹-tetrahydrocannabinol and 1 ng of 11-hydroxy-Δ⁹-tetrahydrocannabinol per ml of plasma.     

Determination of Traces of Mercury (II) and Phenylmercury by Direct Polyurethane foam Thin-Layer Spectrophotometry

Abstract

The determination of mercury and phenylmercury in the ppb concentration range using polyurethane foam (PUF) thin-layer spectrophotometry has been described. Sorption of mercury and phenylmercury into foam parallepiped loaded with diphenylthiocarbazone (dithizone) contributed to considerable improvement in the absorbance value of the colored species, being concentrated about 140 times.

The method allowed the achievement of satisfactory results, the detection limits are 5 and 10 μg per litre for mercury and phenylmercury, respectively, for 100ml sample volume. The average recovery from tap water amounts to 100% for mercury and 96.6% for phenylmercury.     

Kinetic Spectrophotometric Determination of Metoprolol Tartrate in Commercial Dosage Forms

A kinetic spectrophotometric method has been described for the determination of metoprolol tartrate in commercial dosage forms. The procedure is based on the reaction of the drug with 1‐chloro‐2, 4‐dinitrobenzene (CDNB) in dimethylsulfoxide (DMSO) at 100 ± 1 °C. The reaction is investigated by measuring the change in absorbance with time at 420 nm. Fixed‐time (ΔA) and equilibrium methods are chosen for obtaining the calibration curves. Both calibration curves were found to be linear over the concentration range of 5‐60 μg mL^?1. The regression analysis of calibration data resulted in the linear regression equations of ΔA = ?1.608 × 10^?4 + 3.96 × 10^?3 C and A = 7.31 × 10^?4 + 1.90 × 10^?2 C for fixed time (ΔA) and equilibrium methods, respectively. The limit of detection (LOD) for fixed time and equilibrium methods are 1.16 and 0.415 μg mL^?1, respectively. The method has been successfully applied to the quantitation of metoprolol tartrate in commercial dosage forms. Statistical comparison of the results shows that there is no significant difference between the proposed methods and El‐Ries's spectrophotometric method.     

Detection and Spectrophotometric Determination of Uranyl Ion with Erichromcyanine R

Abstract

Colour reaction has been studied for the identification and the spectrophotometric determination of uranyl ion with Erichromcyanine R. The detection limit was 7 μg. Beers law is obeyed in the concentration range containing 13 μg to 125 μg/10 ml of uranium.     

Spectrophotometric Determination of Chlorzoxazone in pure State and Formulations Through Oxidative Coupling of its Hydrolysis Product

ABSTRACT

Three simple and sensitive procedures (Methods A, B and C) for the assay of chlorzoxazone (CZZ) in pure form and in formulations are described. The methods are based on the oxidative coupling reaction of the hydrolysis product of chlorzoxazone (HCZZ) with 3-methyl-2-benzothiazolinone hydrazone (MBTH) in the presence of Fe (III) (Method A, λ_max 445 nm), N, N-dimethyl-p-phenylene diamine (DMPD) in the presence of periodate (IO₄) (method B, λ_max 605 nm) and 2, 6-dichloroquinone chlorimide (DCQC) (Method C, λ, _max 560 nm). The Beer's law limits were found to be 5.0 to 25.0 μg/ml in the case of methods A and B and 2.0 to 12.0 μg/ml in the case of method C. The results are statistically validated and the reactions involved are presented.     

Sensitive Spectrophotometric Determination of Some Dibenzazepine Drugs with Diazotized P-Phenylenediamine Dihydrochloride

ABSTRACT

A simple, sensitive and selective spectrophotometric procedure was developed for the determination of imipramine hydrochloride, desipramine hydrochloride, clomipramine hydrochloride and trimipramine maleate belonging to dibenzazepine class of drugs. The method is based on the interaction of diazotized p-phenylenediamine dihydrochloride with the drug in sulphuric acid medium. The resulting chromophore was measured at 565 nm, and was stable for about 2.5 hr. The commonly encountered excipients and additives do not interfere with the determination. Dibenzazepine drugs can be determined in the range of 0.1-4.0 μg/ml, with a relative standard deviation of 1.92% for ten replicate measurement of 2.0 μg/ml dibenzazepine drugs. Results from the analysis of preformulations and commercial tablets by this procedure agree well with those of the official method.     

Flow Injection Analysis for Beryllium Determination With Chrome Azurol S as Chromogenic Agent

Abstract

A flow injection analysis system which employs a visible absorption detector is used for the determination of beryllium. Be(II) ions are detected by means of a complexation reaction between Be(II) and chrome azurol s as the chomogenic reagent. The reaction forms a stable 1:1 complex which appears dark red-violet. The optimum conditions for the determination are pH 4.15, 35% chrome azurol s, 3% buffer, 62% HCI and 1,3-phenylenediamine, flow rate of 1.0 mL/min, and wavelength at 570 nm. A concentration limit of 0.1 μg/mL (or 2 ng in 25 μ of a sample injected) of Be(II) can be detected, and the linear dynamic range extends to 100 μg/mL. Some interference limits are established in the presence of EDTA and thiosulfate which are used as masking agents.     

A Validated Ion-Pairing High Performance Liquid Chromatographic Method for the Determination of Enoxacin and its Metabolite Oxo-Enoxacin in Plasma and Urine

Abstract

A rapid, sensitive, and specific determination of enoxacin and its principal metabolite, oxo-enoxacin, in plasma and urine is described. the method, which employs the structurally related compound ciprof loxac in as internal standard, involves a protein precipitation step for plasma and solid-phase extraction for urine. Liquid chromatographic analysis is carried out on a C-18 bonded silica column; the mobile phase consists of 0.1 M citric-acid/acetonitrile employing ammonium perchlorate and tetrabutyl-ammonium hydroxide as ion-pairing agents. Quantitation is performed by UV-detection at 340 nm.

The analytical method was validated by examining the performance characteristics specificity, linearity, precision, accuracy, sensitivity, and recovery. Enoxacin calibration curves were linear between 0.02 and 3.2 μg/ml of plasma and from 0.5 to 125 μg/ml of urine. Limits of quantitation in plasma and urine were 0.01 and 0.5 μg/ml, respectively. For oxo-enoxacin, linear of calibration curves were obtained i n the range 0.05 to 1.6 μg/ml (plasma) and 1 to 50 μg/ml (urine); the respective quantitation limits were approximately 0.02 and 1 μg/ml.

The present assay procedure has been applied to monitoring plasma and urine concentrations in several pharmacokinetic studies in humans and different animal species.     

Spectrophotometric Determination of Certain Local Anaesthetics in Pharmaceutical Preparations

Abstract

A direct colorimetric method was described for the rapid, sensitive and accurate determination of dibucaine, lidocaine, bupivacaine, procaine and tetracaine in pharmaceutical preparations. The method involves the use of haematoxylin reagent in the presence of boric acid to give a reddish-violet chromogen (λ_max = 555 nm). Beer's law was obeyed in the range from 2–60 μg/ml. No interference was observed from the commonly present additives or agents in pharmaceutical formulations.     

Spectrophotometric Determination of Some Pharmaceutical Compounds Using 2,2-Diphenyl-1-picrylhydrazyl

Abstract

A spectrophotometric method for the determination of some pharmaceutical amides, hydrazides and thiols is described. The method is based on the reaction of the studied drugs with 2,2-diphenyl-1-picryl hydrazyl (DPPH). The latter is employed to abstract a hydrogen atom from the drugs thereby promoting a process of radical coupling. This results in a reduction of the violet colour of DPPH with the formation of the yellow coloured 2,2-diphenyl-1-picrylhydrazine (DPPH₂). This fading in colour of DPPH reagent depends on the concentration of the drug being determined. Beer's law is obeyed in the ranges of 1–5 μg/ml (for isocarboxazid and gliclazide), 0.25–2.5 μg/ml (for isoniazid), 0.5–5 μg/ml (for iproniazid), 1–7 μg/ml (for tolazamide), 2–15 μg/ml (for captopril) and 1–6 μg/ml (for sulphathiourea). The validity of the method was tested by analysing the studied drugs in pure form as well as in tablets. Results of analyses were compared statistically with the official or reported methods.     

Simultaneous Analysis of Pyridoxine and Melatonin in Tablet Formulation by Derivative Ultraviolet Spectroscopy

Abstract

A method for simultaneous analysis of pyridoxine and melatonin by second and third derivative UV - spectroscopy, the “zero - crossing” technique, is described. The determination has been carried out in 0.1 mol dm^?3 hydrochloric acid solution and the concentration range of 2 – 10 μg/ml pyridoxine and 0.5 – 3.5 μg/ml melatonin. Lower limits of detection at the 95% confidence level were 0.26 μg/ml for pyridoxine and 0.05μg/ml for melatonin The advantages of the proposed method include its application for the assay and in-vitro dissolution studies of pyridoxine and melatonin from two different tablet formulations.     

Isonitroso-4-Methyl-2-Pentanone for Solvent Extraction and Spectrophotometric Determination of Palladium (II) at Trace Level

Abstract

Isonitroso-4-methyl-2-pentanone (HIMP) is proposed as a new reagent for extraction and photometric determination of Pd(II). The reagent forms a yellow complex with palladium in the pH range 4.0-5.0. The complex extracted into chloroform was measured at 330 nm. The molar absorptivity was found to be 5.37 × 10³ 1 mol^?1 cm^?1 and Sandell's sensitivity 20 ng cm^?2 Beer's law was obeyed over the concentration range 0.1-10.0 μg/ml of palladium. The method is applicable for palladium estimation in Ores and catalysts.     

Preconcentration and Spectrophotometric Determination of Chromium (VI) and Total Chromium in Drinking Water by the Sorption of Chromium Diphenylcarbazone with Surfactant Coated Alumina

Abstract

A simple and inexpensive method for determining chromium (VI) in drinking water by spectrophotometry after preconcentration with sodium dodecyl sulphate (SDS) coated alumina column is described. Chromium(VI) is reacted with diphenylcarbazide (DPC) and the Cr-DPC complex is quantitatively adsorbed onto a SDS coated alumina column from 800 ml of sample solution. The complex is then eluted with a 8 ml mixture of methanol, acetone and hydrochloric acid and determined by spectrophotometry. Total chromium can be determined after oxidation of chromium (III) to chromium (VI) by KMnO₄. The relative standard deviation (10 replicate analyses) at the 10 μg l^?1 of chromium (VI) and 10 μg l^?1 of total chromium were 3.5% and 3.4% and corresponding limits of detection (based on 3 σ) were 0.040 μg l^?1 and 0.033 μg l^?1, respectively.