Spectrophotometric Determination of Methyldopa in Pure and Pharmaceutical Preparations

Abstract

Methyldopa reacts with barbituric acid to give a red colour having maximum absorbance at 540 nm. The reaction is selective for methyldopa with 0.01 mg/ml as visual limit of quantitation and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer's Law from 0.1 mg to 2.5 mg/10 ml of methyldopa and the relative standard deviation is 1.1%. The quantitative assessment of tolerable amount of other drugs is also studied.     

Spectrophotometry Determination of Amitriptyline-HCl in Pure and Pharmaceutical Preparations.

ABSTRACT

Amitriptyline-HCl reacts with ammonium molybdate in concentrated sulphuric acid after heating for 20 min. at 100°C to give a green colour having maximum absorbance at 660 nm. The reaction is selective for amitriptyline with 0.01 mg/10ml as visual limit of identification and provides a basis for a new spectrophotometric determination. The reaction obeys Beer's law from 0.01 mg to 1.4 mg/10ml of amitriptyline-HCl and the relative standard deviation is 0.35%. The quantitative assessment of tolerable amount of other drags is also studied.     

Spectrophotometric Determination of Barbituric Acid

Abstract

Barbituric acid reacts with chloral hydrate in alkaline media, after heating for 1 min. at 100°C to give an orangish yellow colour having maximum absorbance at 450 nm. The reaction is selective for barbituric acid with 0.01 mg/ml as the visual limit of quantitation and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer's Law from 0.001 to 0.6 mg/ml and the relative standard deviation is 1.1%. The quantitative assessment of tolerable amounts of other drugs is also studied.     

A Simple Isocratic High-Performance Liquid Chromatographic (HPLC) Determination of Naproxen in Human Plasma using a Microbore Column Technique

Abstract

A simple and sensitive HPLC method was developed for the determination of naproxen in human plasma. The assay employs a microbore column packed with a C18 reversed-phase material (5 μm ODS Hypersil) with an isocratic mixture of acetonitrile and 10 mM phosphate buffer, pH 2.5 (40:60, v/v) as the mobile phase. The mobile phase was pumped at a flow rate of 0.5 ml/min. For sample analysis 200 μl of acetonitrile containing internal standard (flurbiprofen) was added to 100 μl of plasma. After centrifugation 10 mM phosphate buffer, pH 7.4 (200 μl) was added to the tube, then vortexed and centrifuged. The supernatant (20 μl) was injected onto the HPLC column. The chromatographic separation was monitored by a fluorescence detector at an emission wavelength of 350 nm with an excitation wavelength of 225 nm. The direct precipitation of plasma protein using acetonitrile gave a good recovery for both naproxen and the internal standard. The detection limit was 0.1 μg/ml for naproxen. The intra- and inter-assay coefficients of variation at different concentrations evaluated were less than 10%.     

Spectrophotometric determination of isonicotinic acid hydrazide

Summary Isonicotinic acid hydrazide reacts with 2,3,5-triphenyltetrazolium chloride in acidic medium in presence of excess of thallium(III) to give a pink-coloured formazan having maximum absorption at 480 nm. This colour reaction is used to determine isonicotinic acid hydrazide in urine and blood. The reaction is specific for isonicotinic acid hydrazide, and the visual limit of identification is1 g per ml.

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Zusammenfassung Isonikotinsäurehydrazid reagiert mit 2,3,5-Triphenyltetrazoliumchlorid in saurem Milieu bei Gegenwart von überschüssigem Thallium(III) unter Bildung eines rosa gefärbten Formazans mit dem Absorptionsmaximum bei 480 nm. Diese Farbreaktion wird zur Bestimmung von Isonikotinsäurehydrazid in Harn und Blut verwendet. Sie ist spezifisch. Ihre Erfassungsgrenze beträgt 1g/ml.

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Résumé L'hydrazide de l'acide isonicotinique réagit avec le chlorure de triphényl-2,3,5 tétrazolium, en milieu acide en présence d'un excès de thallium-III, en donnant un formazan coloré en rose dont le maximum d'absorption se situe à 480 nm. On utilise cette réaction colorée pour doser l'hydrazide de l'acide isonicotinique dans l'urine et dans le sang. La réaction est spécifique et la limite d'identification visuelle est de 1g par ml.

     

Novel thermoresponsive water-soluble oligomers based on amphiphilic calixresorcinarenes

Novel water-soluble thermoresponsive oligomers TO1 and TO2 were obtained by reaction of amidoamine tetramethylcalixresorcinarenes (C1) and tetrapentylcalixresorcinarenes (C5) with ethylene glycol diglycidyl ether. The compounds were characterised by ¹H and FT-PGSE NMR, FTIR, static light scattering and elemental analysis. The thermoresponsive properties of oligomers were investigated by spectrophotometry, DLS, FT-PGSE NMR and TEM. The cloud points of oligomers (43 °C for TO1 (5 mg/ml) and 41 °C for TO2 (1.2 mg/ml), respectively) were determined. The influence of salts effect on TO2 cloud points was investigated. The binding of anti-inflammatory drug naproxen (Nap) at 20 °C by TO1 and TO2 and its partial release at cloud points of oligomers in aqueous solution are observed using fluorescence and FT-PGSE NMR methods. New example of creating of thermoresponsive macrocyclic systems on the basis of amidoamine calixresorcinarenes with possibility of substrate binding and release under the influence of termo-stimuli in an aqueous solution was shown.     

Kinetic Spectrophotometric Determination of Trace Amounts of Nitrite Ion Using Its Reaction With Neutral Red

Abstract

A rapid, simple, sensetive and selective method for the determination of trace amounts of nitrite ion(30-800 ng/ml) is developed. It depends on the reaction of nitrite with Neutral Red. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance at 530 nm by a fixed time method. The limit of detection is 14 ng/ml. The method is used for the determination of nitrite ion in waste water.     

Kinetic Spectrophotometric Determination of Acetaldehyde

ABSTRACT

A method for determination of trace quantities of acetaldehyde based on its inhibition effect on the malachite green-sulfite reaction is described. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance at 613 nm by a fixed time method of 60 seconds. The method allows the determination of acetaldehyde in the range of 0.2-10 μg/ml. The limit of detection was 0.1 μg/ml and the relative standard deviation for ten determinations of 2 μg/ml acetaldehyde was 1.8%. The method is applied to the determination of acetaldehyde in chemical industrial waste water with satisfactory results.     

Spectrophotometric and Spectrofluorometric Determination of Heptaminol and mexiletine in Their Dosage Forms

Abstract

Two simple, rapid specific methods were developed for the determination of heptaminol and mexiletine and their dosage forms. The methods are based on the reaction of either heptaminol or mexiletine with acetylacetone-formaldehyde reagent to give a yellow chromophore measurable spectrophotometrically at 344 or 338 nm or flurometrically at 480 nm for heptaminol and mexiletine, respectively. The color was stable for at least 1/2 h. Beer's law was valid within a concentration range of 15–30 and 8–20 μg ml^?1 spectrophotometrically and 0.2–0.8 and 0.4–1.0 μg ml^?1 fluorometrically for heptaminol and mexiletine, respectively.     

Extractionless HPLC Method for the Determination of Naproxen in Human Plasma and Urine

Abstract

A simple and rapid (extractionless) high-performance liquid chromatographic method with ultraviolet detection, at 278 nm, is described for the determination of naproxen in human plasma and urine. Niflumic acid is used as internal standard. The chromatographic system consists of a reversed-phase C18-Spherisorb column with acetonitrile/0.1 M sodium acetate (35:65 v/v, pH 6.14) as the mobile phase. The retention time is 3.0 min for naproxen and 3.8 min for niflumic acid. The total run time is 5 min and the typical assay time is 10 min. The method is sufficiently sensitive for biopharmaceutical studies, after the oral administration of a single sustained release dose.     

Simultaneous Determination of Micro Bromide and Iodide by Kinetic Spectrophotometric Method

ABSTRACT

ABSTRACTA new kinetic spectrophotometric method for the simultaneous determination of concentrations of micro bromide and iodide has been proposed. It is based on their catalytic effects on the reaction of m-cresol purple oxidized by potassium periodate in hydrochloride acid medium. The reaction rate was monitored by measuring the decrease in absorbance at 528nm and the increase in absorbance at 455nm. The total difference in absorbance of the sum of bromide and iodide is identical with determination of bromide was carried out after Cr(VI) oxidized I? to I₂, and I₂ was removed by extraction with CCI₄, and the amount of iodide was measured by subtracting the absorbance change of bromide from the total absorbance change in the presence of bromine and iodide. The optimum conditions influencing the reaction rate were studied. The linear range of determination is 0～4.0μg/ml for Br? and 0～3.0 μg/ml for I?. The detection limits are 0.032μg/ml for Br? and 0.059 μ/ml for I?. The method was successfully applied to the determination of micro amounts of bromide and iodide in food and life samples.     

Second Derivative Ultraviolet Spectrophotometry and High Performance Liquid Chromatography with Fluorometric Detection of Cycloserine Using 9-Chloro-10-methyl Acridinium Triflate as a New UV and Fluorescent Labeling Agent

Abstract

Sensitive and simple second derivative UV spectrophotometric and HPLC with fluorometric detection methods were developed for cycloserine based on derivatization with 9-chloro-10-methyl acridinium triflate (CMAT) to yield a reaction product which absorbs in the UV at 361 nm and is fluorescent using excitation and emission wavelengths of 257 nm and 475 nm, respectively. The CMAT derivatization reaction takes 30 minutes at 70°C. Cycloserine was linear in the 0.3 – 5.0 μg/ml range (r=0.999, n=5) for the second derivative UV method and the 0.8 – 5 μg/ml range for the HPLC method (r=0.999, n=5). The limit of detection for cycloserine in the HPLC method can be improved to 0.15 μg/ml with the addition of glacial acetic acid to the analytical sample. The HPLC assay was applied to the determination of cycloserine in spiked human urine samples. The correlation coefficient (r) was in the 0.999 range and sensitivity was at the low pg/ml level.     

4-Aminoantipyrine as an Analytical Reagent for the Colorimetric Determination of Tetracycline and Oxytetracycline

Abstract

A spectrophotometric method is proposed for the determination of tetracycline and oxytetracycline and their dosage forms. The suggested method depends on the reaction with 4-aminoantipyrine in the presence of an alkaline oxidising agent. A red antipyrine dye is produced. The reaction ratio has been determined. Variables such as pH, temperature, reagent concentration, stability of the colour produced have been evaluated to permit selection of the most advantageous technique. Beer's law was obeyed over the concentration range 0.04 - 0.12 mg/ml and 0.04 - 0.16 mg/ml for tetracycline and oxytetracycline respectively.     

The use of chloranilic acid salts in micro analysis

Summary A quick method for the determination of polymetaphosphates, orthophosphates, pyrophosphates and their mixtures with the help of chloranilic acid salts has been described.By measuring the optical density on a spectrophotometer at 505 nm the following quantities per ml can be determined approximately: polymetaphosphate, orthophosphate and pyrophosphate, 0.05 mg; polymetaphosphates in the presence of orthophosphates, 0.15 mg.

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Zusammenfassung Es wird ein Verfahren zur raschen spektrophotometrischen Bestimmung von Polymetaphosphaten, Orthophosphaten und Pyrophosphaten sowie ihren Gemischen mit Hilfe von Chloranilsäure beschrieben. Hierbei wird die optische Dichte bei 505 nm gemessen. Es können noch 0,05 mg Phosphat/ml bestimmt werden (bei Polymetaphosphat in Gegenwart von Orthophosphat: 0,15 mg/ml).

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Part I: Hoffmann, E.: Z. analyt. Chem. 185, 372 (1962)     

Highly Selective Photometric Method for the Determination of Periodate

ABSTRACT

A simple and selective photometric procedure was developed for the micro-determination of periodate in aqueous media. The method is based on the reaction of periodate with Gallocyanine at pH = 4.8. The reaction was monitored photometrically by measuring the absorbance of the reaction mixture at 620 nm. The effects of reagent concentration, temperature and influence of other species for the determinations of periodate were investigated. Periodate can be determined in the range of 0.02-2.20 μg/ml, with a relative standard deviation of 1.96% for ten replicate measurements of 0.13 μg/ml periodate. Periodate can be determined in the presence of iodate or iodide.     

Fluorometric reactions of purines and determination of caffeine

Two new spot-tests for purines are described together with a new sensitive determination of caffeine. The spot tests involve a fluorometric reaction with 4,5-dimethyl-o-phenylenediamine after oxidation with N-bromosuccinimide. Caffeine treated in this manner exhibits a blue fluorescence with excitation maxima at 340 and 390 nm, and an emission maximum at 480 nm. The fluorometric reaction may be used to determine caffeine in the range 0.01–10, μg/ml with a relative standard deviation of 0.9% for 0.1 μg/ml caffeine. The method has been used to determine caffeine in cough syrups.     

A Chemiluminescence Reaction Between Hydroxyl Radical and Rhodamine 6G and its Applications

Abstract

A novel chemiluminescence (CL) reaction between hydroxyl radical and ascorbic acid is described in this paper. Hydroxyl radical generated on line by the reaction between Fe³⁺ solution and H₂O₂ solution in HCl medium could oxidize rhodamine 6G to produce weak chemiluminescence. It was found that ascorbic acid could enhance the chemiluminescence and the excited rhodamine 6G was the emitter of the chemiluminescence reaction. The possible mechanism of the CL system was also discussed. Ascorbic acid can be determined in the range of 2.0×10^?6?8.0×10^?4 mg/ml with a detection limit of 1×10^?6 mg/ml (3σ). A complete analysis could be done in 1 minute with the relative standard deviation of 3.1% for 5.0×10^?5 mg/ml (n=11). In order to study the chemiluminescence reaction further, the application to the determination of ascorbic acid in food using the chemiluminescence reaction combined with flow injection is investigated.     

Simultaneous Determination of Flunixin,Phenylbutazone, Oxyphenbutazone and γ-Hydroxyphenylbutazone in Equine Plasma by High-Performance Liquid Chromatography: With Application to Pharmacokinetics

Abstract

A high performance liquid chromatographic method was developed for the simultaneous determination of flunixin, phenylbutazone, oxyphenbutazone and γ-hydroxyphenylbutazone in equine plasma. Samples of plasma or sera were deproteinated by addition of acetonitrile containing the internal standard naproxen. The concentration step consisted of taking an aliquot of deproteinated plasma, evaporating under nitrogen to dryness and redissolving in mobile phase. The extracts were chromatographed on a Spherisorb 5 μm ODS column using an isocratic mobile phase of methanol (30% v/v), acetonitrile (20% v/v) and pH 3.0 1% acetate buffer (50% v/v) at a flow rate of 1.2 ml/min using naproxen as the internal standard. The detection limit for flunixin, phenylbutazone, oxyphenbutazone and γ-hydroxyphenylbutazone was 50 ng/ml.

The developed chromatographic method was applied to the determination of equine nonsteroidal anti-inflammatory treatment. Plasma samples from clinically treated horses administered flunixin and phenylbutazone simultaneously are reported. Effect of different anticoagulants used in sampling is reported.     

Spectrophotometric Determination of Narcotine

Abstract

Narcotine reacts with potassium iodate and antimony potassium tartarate to give a yellowish orange colour having maximum absorbance at 430–440 nm. The reaction is specific for narcotine, having 1 ug/10 ml as visual limit of identification and provides a basis for a new spectropho-tometric determination of pure narcotine and in the presence of other drugs. The maximum tolerable limits of these are reported.     

High-Performance Liquid Chromatographic Assay of D-Glucose in Erythrocytes

Abstract

A procedure is presented after several attempts with different modes of chromatography for measuring high concentrations of d-glucose in erythrocytes. The procedure utilizes rapid deproteinization of hemolysate by mixing with acetonitrile. The supernatant is analyzed by strong cation exchange chromatography, using an Organic Analysis Column. Separation conditions are: eluent = 0.01 N H₂SO₄, flow rate = 0.6 ml/min, detection = 195nm at 0.05 AUFS, sample size = 20 μl and temperature = ambient. The coefficients of variation for 5 mg/ml samples were (within-run) 6.7%, and (day-to-day) 7.1%. This study shows the presence of a high concentration (1900 mg/dl) of d-glucose within the erythrocytes as a result of a high external d-glucose concentration (2000 mg/dl) in plasma, and suggests that d-glucose is rapidly transported into the cell.