Determination of cefadroxil by sequential injection with spectrophotometric detector.

A sequential injection analysis (SIA) spectrophotometric procedure for cefadroxil determination has been developed. The SIA instrumentation was modified to achieve the desired function and operations by using the software developed to interface the PC with the conventional SIA system. The method is based on the measurement of a red, water-soluble product formed by the reaction between cefadroxil and 4-aminoantipyrine in the presence of alkaline potassium hexacyanoferrate(III) at 510 nm. Optimum conditions for determining the drug were investigated. Beer's law was obeyed over the concentration ranges of 1 - 10 mg L(-1) and 10 - 50 mg L(-1) with a detection limit (3 sigma) of 0.17 mg L(-1) and a limit of quantification (10 sigma) of 0.56 mg L(-1). The relative standard deviations of 1.98% and 1.93% for 5 mg L(-1) and 30 mg L(-1) of the drug, respectively (n = 11) are obtained. The proposed method has been applied satisfactorily to the determination of cefadroxil in commercial pharmaceutical formulations with a sampling rate of 100 h(-1). Results obtained were in good agreement with those obtained by the official HPLC method at the 95% confidence level.     

Polarographic assay of Ranitidine Drugs in Pharmaceutical Formulations

Abstract

A simple, accurate and rapid method for the quantitative determination of five ranitidine drugs in pharmaceutical formulations (Tablets and Ampoules) is proposed. The supporting electrolyte was acetic acid-sodium acetate buffer solution (pH 5.2). An excellent linear relationship was obtained between the concentration and current with correlation coefficient 0.9996. Good agreement was obtained between the results with the d.c. polarograhic method and those by the manufacturer's method of assay.     

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.     

Direct Determination of Glucose in Blood Serum Using Trinder's Reaction

Abstract

A very simple flow injection analysis system for direct determination of glucose in blood serum based on Trinder's reaction is described. The sera samples (15 μl) can be injected directly to the system without the deproteinization or the use of a dialyzer.

Calibration curves are linear in the range 50–400 mg/dl. The sampling frequency is 60 samples per hour. Results obtained by the proposed procedure are compared with those acquired at a local hospital using their routine glucose procedure also based on Trinder's reaction. It is shown that a better mix between sample and reagents is achieved using the single bead string reactor (SBSR).     

Determination of Trace Bisphenol A in Leachate by Solid Phase Microextraction Coupled with High Performance Liquid Chromatography

Abstract

A rapid determination method for trace bisphenol A in leachate by solid phase microextraction (SPME) coupled with high performance liquid chromatography (HPLC) was developed. The experimental condition of SPME, such as select operation, solid phase microextraction fibers, pH, extraction time, extraction temperature, desorption time, desorption solution, mode, and the analytical conditions of HPLC were optimized. As compared with the graph that was produced by HPLC alone, the graph by only HPLC couldn't analyze bisphenol A and compared to the results of three solid‐phase microextraction fibers. The linear range was between 0.0128 mg/L and 0.192 mg/L in this method, and the correlative coefficient was 0.9975. Limits of detection, repeatability, and reproducibility were also determined. The limit of detection of this method was 3.25 µg/L (3σ, n=11). The relative standard deviation (RSD, n=3) was 4.4%. The method was used for the determination of trace bisphenol A in leachate of Qingshan landfill and leachate of Liufang landfill. The recoveries were between 94.5% and 103.3%. This method is fast, convenient, sensitive, solvent free, and suitable for the determination of trace bisphenol A in leachate.     

Permanganate-based chemiluminescence analysis of cefadroxil monohydrate in pharmaceutical samples and biological fluids using flow injection

A chemiluminescent method using flow injection is described for the determination of cefadroxil monohydrate. The method is based on the chemiluminescence reaction of cefadroxil with potassium permanganate in sulphuric acid, sensitized by quinine. The proposed procedure allows the determination of cefadroxil over the concentration range 0.1-30 mug ml(-1) with a detection limit of 0.05 mug ml(-1) and a sample measurement frequency of 150 samples h(-1). The method was successfully applied to the determination of cefadroxil in pharmaceutical preparations and biological fluids.     

Spectrophotometric Determination of Cefadroxil and Metyrosine in Dosage Forms

Abstract

A simple and sensitive spectrophotometric method is described for the determination of cefadroxil and metyrosine in pure form and in pharmaceutical formulations. The method is based on reacting these drugs with 4-aminoantipyrine (AAP) in the presence of an alkaline oxidising agent. The coloured products were measured spectrophotometrically at 500 nm and 470 nm for cefadroxil and metyrosine, respectively. Beer's law was obeyed over the concentration range 1-28 and 2-44 μg ml^-1 for cefadroxil monohydrate and metyrosine, respectively. The molar ratio in both cases was established and a proposal for the reaction pathway was suggested. The percentage recoveries obtained were in accordance with those given by the reference methods.     

Spectrophotofluorimetric Determination of Trace Amounts of Aluminium with 2,2′-Dihydroxy-3,3′-dicarboxy-1, 1′-Dinaphthylmethane (Pamoic Acid)

Abstract

Fluorescence properties of 2,2′-dihydroxy-3,3′-dicarboxy -1,1′-dinaphthylmethane (pamoic acid) and of its aluminium 1:1 complex are described. The fluorescence of the latter, as measured from a water-dioxane (3:7, v/v) solution, at pH 5.05–5.20, at room temperature, is used as a basis for a new method of aluminium determination at submicrogram level. Limit of quantification of the proposed procedure is 0.028 ng.ml^?1, range of applicability goes up to 1.7 ug.ml^?1, RSD is 1% at 0.47 ug.ml^?1 level (concentrations, given refer to HCl solution which is measured) Tolerance ratios for several interferent metal ions are given. A comparison is made with Kirkbright's method which uses 3-hydroxy-2-naphthoic acid as complexing agent: stability with time of the readings and freedom from Fe(III) interference are the main advantages of the proposed procedure. The new method is applied to the aluminium determination in atmospheric aerosol samples.     

Rapid High Performance Liquid Chromatographic Determination of Ampicillin in Human Urine

Abstract

A rapid, sensitive and specific HPLC assay for the determination of ampicillin in human urine is developed.

Ampicillin was directly measured in human urine at 225 nm using a reversed phase column (Synchropack RP-P) and a mobile phase composed of (1:9 methanol-sodium acetate solution, 0.01 M, pH 4). The analysis required no longer than 10 min. Linear correlation between the peak height ratio of ampicillin to cefoxitin sodium (internal standard) and ampicillin concentration in urine over the range 10–100 μg ml^?1 was obtained. The developed method proved to be advantageous as it monitors ampicillin level in urine. Moreover, the urinary excretion of ampicillin in human subjects after an oral administration of 500 mg ampicillin capsules was established using the proposed method.     

Extractive Spectrqphotometric Determination of Vanadium Liith o-Aminobenzo-Hydroxamic Acid

Abstract

A new spectrophotometric method for vanadium determination is proposed. The method is based on the extraction in Adogen-toluene solution of the complex formed between V(V) and o-Aminobenzohydraxámic acid

The method allows determination of 50 to 110 μg of V(V). The error and the apparent molar absorptivity are 1.2% and 5.2 ± 10³ l.mol^?1. cm^?1 respectively. The interferences caused by foreign ions have been established. The method is applied with success to determination of vanadium in petroleum crudes.     

Spectrophotometric determination of Blue Procion HEGN in effluents of textile industry exploiting the dye aggregation effect and flow injection analysis.

A new spectrophotometric method involving flow injection analysis and textile dye aggregation effect is proposed. The method is based on the aggregation effect of Blue Procion HEGN at pH 3, which relocates its maximum absorption wavelength from 620 to 776 nm, avoiding the interference of other blue textile dyes. For this task, a simple and robust flow injection system was designed, which became a very stable analytical method. When the system was applied to Blue Procion determination in effluent of textile industry, precise results were observed (RSD < 2% within 1.0 and 5.0 mg l(-1) HEGN). The analytical frequency was 80 measurements per hour; the analytical curve was linear from 1.0 to 5.0 mg l(-1) HEGN; the detection limit considering three times the standard deviation of the blank solution (n = 10) was estimated as 0.03 mg l(-1) HEGN; and recoveries between 95% and 105% were found. The system consumes 20 mg of sodium citrate and 125 microl of the sample per determination. No baseline drift was observed during extended (5 h) operation periods.     

Determination of Propantheline Bromide in Tablet Formulations by Reverse-Phase HPLC

Abstract

The reported reverse-phase HPLC method for the determination of propantheline bromide, xanthanoic acid, xanthone, and 9-hydroxy-propantheline bromide in tablets is fast, sensitive, specific, accurate and reporoducible. Methyl xanthanoate is used as internal standard. The total elution time is 6 min. The method is stability-indicating since it can determine the degradation products. The column utilized was suplecosil LC-8 (5 micron), 250 mm × 4.6 mm i.d. The mobile phase was 0.03 M solution of ammonium acetate in acetonitrile: water: THF (60:38:2); the pH was adjusted to 4.5 with acetic acid, the detection was at 254 nm. A wavelength of 248 nm was used to quantitate xanthanoic acid and the flow rate was 1.5 mL/min. The proposed HPLC method was verified for linearity, accuracy, precision, and applicability.     

Flow Injection Analysis of Famotidine with Spectrophotometric Detection

Abstract

A flow injection determination of famotidine has been described. The method is based on the reaction of the drug with cupric acetate to form a blue coloured complex which shows absorption maxima at 314 nm and 630 nm. For an injection volume of 100 μl calibration graphs were rectilinear from 10- 50 μg. ml^?1 and 50–500 μg.ml^?1 of drug at the two wavelengths respectively. Samples could be analysed at rates upto 60 per hour with a relative standard deviation less than 1.4%. The method was evaluated by analysis of the pure drug and commercial formulations. The results compare well with those obtained by official methods.     

Rapid Determination of Aldehydes in Air Analyses

Abstract

A simple analytical method for aldehyde determinations in ambient air is described. The method involved trapping the aldehydes as their DNPH derivatives in acetonitrile solution and then direct injection and analysis of the resulting solution on a reversed phase HPLC column with simultaneous detection at 254 and 360 nm. Several comparison studies are described.     

In-line flow injection extraction-preconcentration through a passive hydrophilic membrane. Determination of total phenols in oil by flow-injection analysis

 An in-line flow injection extraction-preconcentration procedure for the determination of total phenols in oil is described. The reaction between phenolic compounds and 4-aminoantipyrine in the presence of K₂S₂O₈ as oxidizing reagent was used. The phenols were extracted and preconcentrated from a xylene solution by using a more selective passive hydrophilic Spectrapor membrane which also removed interferences. The phenols deprotonated after diffusion to the basic acceptor stream and the preconcentrated phenolate was injected into a carrier stream containing 4-aminoantipyrine as colour reagent. The carrier stream then merged with the oxidant stream, followed by detection at 500 nm. The system was suitable for the determination of total phenols in oil at a sampling rate of 12 samples per hour with an RSD of better than 1.3%. The detection limit was 0.09 mg/l for phenol, 0.18 mg/l for o-cresol and 0.02 mg/l for m-cresol. The results of the proposed system compared favourably with a standard manual 4-AAP method and a standard GC procedure. Received: 30 July 1996/Accepted: 25 August 1996     

A Selective Colorimetric Method for the Determination of Penicillins and Cephalosporins with α-Aminoacyl Functions

ABSTRACT

A simple, sensitive and selective colorimetric method is described for the assay of ampicillin, amoxicillin, cephalexin, cefadroxil and cefaclor in their pharmaceutical preparations. The method is based on measuring the color obtained when the alkaline degradation products of these agents are allowed to react with ascorbic acid. The factors affecting the color generation and determination were studied and optimized. The reaction is selective to β-lactam antibiotics having amino acid side-chains with free amino functions and thus allow interference-free quantitation of some preparations containing these agents in combination with other β-lactam agents. The procedure is also successfully adopted as stability-indicating method for cephalosporins. A tentative mechanism of the color reaction is proposed.     

Determination of Saccharin in Plasma and Urine by High Performance Liquid Chromatography

Abstract

A sensitive and specific high performance liquid chromatographic (HPLC) assay for the determination of saccharin in plasma and urine was developed. Saccharin is extracted into diethyl ether at acid pH, evaporated, and reconstituted prior to instrumental analysis. Overall recovery of saccharin is 86.9 + 8.6% and the sensitivity limits of detection is 0.15 μg per ml of plasma or urine using a fluorescence detector. The sensitivity limit in plasma can be extended to 20 ng per ml by use of a 2 ml assay volume and detector attenuation. The assay was used for the determination of saccharin in plasma and urine of rats following oral doses of 5 mg/kg.     

L, 8-Dihydroxyanthraquin0Ne-Li(I) Reaction. Spectrofluorometric Determination Of Li(I) In An Ethanolic And Acetonic Media

Abstract

A spectrofluorometric study of the reaction 1, 8-Didydroxv anthraquinone-Li(I) was made in ethanol and acetone media. A new method for the spectrofluorometric determination of Li(I) is proposed, with a range between 100 and 700 ppb of Li(I) in ethanolic medium and between 50 and 450 ppb in acetone medium. The methods show errors of 2.00 and 2.90 % respectively.     

Rapid Determination of Teicoplanin in Human Plasma by High Performance Liquid Chromatography

Abstract

A rapid isocratic reversed-phase HPLC method for the determination of the major component of teicoplanin in plasma is described.

By using solid phase extraction C18 and UV detection at 240 nm, this method is specific, and sufficiently sensitive.

We found a good linearity over the range: 5 – 40 mg/1 of teicoplanin plasma concentrations. The coefficients of variation did not exceed 5.4% both within-day and between-day assays.

With the small plasma sample required for the analysis (250 μl) and the good accuracy, this rapid procedure appears to be suitable for the therapeutic drug monitoring.     

Determination of Mescaline in Hallucinogenic Cactaceae by Ion-Interaction HPLC.

Abstract

An ion-interaction HPLC method is developed for the determination of mescaline in some Cactaceae species, namely Gymnocactus beguinii, Echinocactus polycephalus, Coriphanta radians, Coriphanta scolymoides, Coriphanta palmeri, Lophophora williamsii and Trichocereus pachanoi.

Mescaline is characterized by hallucinogenic properties and can be prescribed as a psychodrug.

The method makes use of a C18-reversed-phase as the stationary phase and of a 5.0 mM aqueous solution of octylamine o-phosphate as the mobile phase, with spectrophotometric detection at 230 nm.

The method is sensitive (detection limit of 35 μg/L) and matrix interference-free.

The pretreatment of the sample is performed by grinding the fresh cactus and extracting the jelly pulp obtained either with a methanolic-ammonial solution or an aqueous solution buffered at pH 4.0 (phosphate buffer).

The average amounts of mescaline found in Lophophora williamsii and in Trichocereus pachanoi were respectively 2.55 mg and 3.10 mg/g of fresh cactus.