Mustafa A. Abuirjeie

Utility of iodine and 7,7,8,8-tetracyanoquinodimethane for determination of terfenadine.

Simple and sensitive spectrophotometric methods for the assay of terfenadine are described. The first is based on the reaction of terfenadine with iodine to give a molecular charge-transfer complex, the terfenadine acting as an n-electron donor and iodine as a sigma-electron acceptor. The second depends on the formation of a highly coloured stable radical anion between terfenadine and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as a pi-electron acceptor. Beers law is obeyed over the terfenadine concentration range 0.2-1.2 mg/100 ml. The proposed methods have been successfully applied to the analysis of commercial terfenadine tablets.

Determination of diazepam and oxazepam using high-performance liquid chromatography and fourth-derivative spectrophotometric techniques

Accurate and very precise HPLC and fourth-derivative ultraviolet spectrophotometric methods for the determination of diazepam and oxazepam in dosage forms are described. The methods are capable of distinguishing the intact drugs from their hydrolytic degradation products at 6 M hydrochloric acid. Mean recoveries for mixtures containing the drugs and their degradation products were found to be 101.3 ± 2.5 and 101.4 ± 1.8% using the HPLC procedure and 100.8 ± 2.0 and 101.0 ± 2.7% using the fourth-derivative spectrophotometric technique for diazepam and oxazepam, respectively. The reported procedures have been successfully applied to monitoring either diazepam or oxazepam in pharmaceutical formulations.

Simultaneous High-Performance Liquid Chromatographic Assay of Acetaminophen, Acetylsalicylic Acid, Caffeine, and D-Propoxyphene Hydrochloride

Abstract A reversed phase high-performance liquid chromatography (HPLC) method for simultaneous measurement of acetaminophen (I), acetylsalicylic acid (II), caffeine (III) and d-propoxyphene (IV), using phenacetin (V) as an internal standard was developed. Using a 6.5 μ C-8 reversed phase column (RPP) with a mobile phase consisting of 0.01M sodium acetate solution: methanol (85:15%) at pH 4.1 enabled the Chromatographic separation of the four components in about 12 min. Quantitation was achieved by measuring the peak height ratio of each component relative to the internal standard. the validity of the developed method was tested by analyzing laboratory-prepared mixtures containing the four components in various proportions. Assay precision and sensitivity have been established for each component. the developed method proved to be stability-indicating as it can be applied to monitor salicylic acid as a degradation product in acetylsalicylic acid samples.

Simultaneous Determination of Acetaminophen with Orphenadrine Citrate, Ibuprofen or Chlorzoxazone in Combined Dosage Forms by Zero-Crossing Derivative Spectrophotometry

Abstract A derivative spectrophotmetric procedure for the simultaneous determination of acetaminophen-orphenadrine citrate, acetaminophen-ibuprofen and acetaminophen-chlorzoxazone, binary mixtures is described. The procedure minimises the mutual interference between these drugs in mixtures and allows the determination of these compounds without a previous extraction step. The precision of the method, expressed as the relative standard deviation, is better than 4%. The method has been successfully applied to laboratory mixtures and commercial tablets containing these drugs.

Vitamin D3 and its metabolites in tomato, potato, egg plant and zucchini leaves

Abstract The presence of vitamin D3 (cholecalciferol) and its hydroxylated metabolite 25-hydroxyvitamin D3 (25-OH D3) was established in leaf extracts of Lycopersicon esculentum, Solanum tuberosum, S. melongena and Cucurbita pepo. Free vitamin D3 was detected in all the leaves of these plants with the exception of S. melongena. 25-OH D3 was detected only in the extract of L. esculentum. However, neither 1α-OH vitamin D3 (1α-OH D3) nor 1α,25(OH)2 D3 (calcitrol) was detected in any of the leaf extracts of these plants; no glycosides of either vitamin D3 or its hydroxylated metabolites were found.

Simultaneous determination of theophylline and guaiphenesin by third-derivative ultraviolet spectrophotometry and high-performance liquid chromatography

Two methods are described for the simultaneous determination of theophylline and guaiphenesin in combined pharmaceutical dosage forms. The first method depends on third-derivative ultraviolet spectrophotometry, with the zero crossing technique of measurement. Third-derivative amplitudes at 222 and 278 nm were selected for the assay of guaiphenesin and theophylline, respectively. The second method is based on high-performance liquid chromatography on a reversed-phase column using a mobile phase of 0.01 mol dm-3 sodium dihydrogen phosphate-methanol-acetonitrile (8 + 2 + 1) (pH 5.5) with detection at 245 nm. Both methods showed good linearity, precision and reproducibility. The proposed methods were successfully applied to the determination of these drugs in laboratory-prepared mixtures and in capsules or elixir.

Determination of Theobromine, Theophylline, and Caffeine in Various Food Products Using Derivative UV-Spectrophotometric Techniques and High-Performance Liquid Chromatography

Abstract Accurate, sensitive and precise derivative ultraviolet Spectrophotometric and high-performance liquid chromatographic (HPLC) methods are described for the simultaneous determination of three natural methyl xanthines (theobromine, theophylline and caffeine) in various food products. The derivative UV-spectro-photometry, with zero crrosing technique of measurement was selected for determination of theobromine and theophylline. First-derivative procedure (D1) was adopted for theobromine determination in the presence of theophylline and caffeine; and second-derivative procedure (D2) was adopted for theophylline determination in the presence of theobromine and caffeine. Caffeine was determined by compensation method using the zero order spectrophotometry. The second method was based on HPLC on a reversed phase column, using a mobile phase of 0.01 M sodium acetate solution: acetonitrile (85:15%) at PH 4.0 with detection at 272 nm. Both methods show good linearity, precision and reproducibility. The dev...

Spectrophotometric determination of chloramphenicol using orthogonal polynomials.

A direct spectrophotometric method using combined orthogonal polynomials (PW) for the determination of chloramphenicol in the presence of its alkali-induced degradation products is described. Mixtures of the intact drug with its degradation products were prepared and their absorbances were measured over the wavelength range 248–314 nm. The pW coefficient calculated over this range at 6-nm intervals was found to be reproducible and independent of the degradation products. The proposed method proved to be applicable to monitoring chloramphenicol stability.

Simultaneous High-Performance Liquid Chromatographic and First-Derivative Spectrophotometric Determination of Amitriptyline Hydrochloride and Chlordiazepoxide In Capsules

Abstract Rapid, precise, accurate and specific high-performance liquid chromatographic and first-derivative spectrophotometric procedures were described for the simultaneous analysis of amitriptyline and chlordiaze-poxide in two-component capsule formulations. A reversed phase Micropack MCH-5 (CI8) column with a mobile phase composed of acetonitrile/water in a ratio (50:50) at pH3 and containing 0.01 M sodium-n-octane sulfonate separated amitriptyline, chlordiazepoxide and diazepam (internal standard). the drugs were detected at 230 nm at ambient temperature. the trough amplitudes in the first derivative spectrophotometric spectra at 245 nm and 282 nm were selected to determine amitriptyline and chlordiazepoxide. Commercial capsules and laboratory-prepared mixtures containing both drugs in different proportions were assayed using the developed methods. the results were of comparable accuracy as indicated by the statistical analysis of data using t-test and F-test.

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.