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At least 19 recordsLinked to original sources
PubMed1998

[Comparison of two methods of ultraviolet spectrophotometry methods of a mixture of paracetamol/acesulfam-K].

Ultraviolet spectrophotometry can help determined the quantity of paracetamol and acesulfam-K when mixed. The isosbestic wavelength (lambda iso) and the absorbency at the wavelength (Aiso) determined with equimolecular solutions or by annulation of the first derivative at 226 nm for paracetamol determination and at 242.5 nm for acesulfam-K determination can be used.

Acetaminophen↗
PubMed2001

Simultaneous determination of valsartan and hydrochlorothiazide in tablets by first-derivative ultraviolet spectrophotometry and LC.

First-derivative ultraviolet spectrophotometry and high-performance liquid chromatography (HPLC) were used to determine valsartan and hydrochlorothiazide simultaneously in combined pharmaceutical dosage forms. The derivative procedure was based on the linear relationship between the drug concentration and the first derivative amplitudes at 270.6 and 335 nm for valsartan and hydrochlorothiazide, respectively. The calibration graphs were linear in the range of 12.0-36.1 microg x ml(-1) for valsartan and 4.0-12.1 microg x ml(-1) for hydrochlorothiazide. Furthermore, a high- performance liquid chromatographic procedure with ultraviolet detection at 225 nm was developed for a comparison method. For the HPLC procedure, a reversed phase column with a mobile phase of 0.02 M phosphate buffer (pH 3.2)-acetonitrile (55: 45; v/v), was used to separate for valsartan and hydrochlorothiazide. The plot of peak area ratio of each drug to the internal standard versus the respective concentrations of valsartan and hydrochlorothiazide were found to be linear in the range of 0.06-1.8 and 0.07-0.5 microg x ml(-1), respectively. The proposed methods were successfully applied to the determination of these drugs in laboratory-prepared mixtures and commercial tablets.

Antihypertensive Agents↗
PubMed1991

Determination of serum acetaminophen in emergency toxicology: evaluation of newer methods: Abbott TDx and second derivative ultraviolet spectrophotometry.

Newer methods for the determination of serum acetaminophen in emergency toxicology, the Abbott TDx immunoassay and second derivative ultraviolet spectrophotometry, were evaluated and compared to a high pressure liquid chromatographic procedure. The Abbott TDx immunoassay within-run and day to day precision yielded coefficients of variance below 2.7% and 7.2% respectively: Abbott TDx immunoassay results correlated well with those of high pressure liquid chromatographic in patient serums 15.0 to 333 mg/L acetaminophen; r2 = 0.954, n = 40. The Abbott TDx immunoassay assay was rapid, easy to perform, free of interferences from other drugs and exhibited no carryover from previous samples. The within run precision of the second derivative ultraviolet spectrophotometry method yielded coefficients of variance of less than 7.0%. Second derivative ultraviolet spectrophotometry results demonstrated good correlation with high pressure liquid chromatographic results in patient sera; r2 = 0.923, n = 40; however, performance deteriorated below 50.0 mg/L acetaminophen. Spectral interferences were noted at high concentrations of some drugs.

Acetaminophen↗
PubMed1975

Ultraviolet spectrophotometry of theophylline in plasma in the presence of barbiturates.

Ultraviolet spectrophotometry is widely used for the analysis of theophylline in blood, for purposes of monitoring therapy, and for pharmacokinetic studies. Phenobarbital, a component of common oral theophylline preparations, interferes with assays now in use. The modification of the method of Schack and Waxler [J. Pharmacol. Exp. Ther. 97, 283 (1949)] presented in this paper eliminates barbiturate interference. After solvent extraction and back extraction into NaOH, the pH of the alkaline solution is adjusted from pH 13 to 10 before spectrophotometric measurement. This shifts the barbiturate absorption maximum from 255 to 240 nm, permitting accurate analysis of theophylline, the spectrum of which is unaffected by the pH change.

Humans↗
PubMed1978

Improved ultraviolet spectrophotometry of serum theophylline.

We present an improved method for ultraviolet spectrophotometry of theophylline in serum. We studied various extraction techniques aimed at eliminating interferences from co-extractable serum constituents. In the resulting modified procedure, 1 ml of serum is required and a salt-solvent pair of ammonium sulfate and chloroform/hexane is used for extraction. The solvent forms the top phase after extraction, the lower phase after back-extraction, thereby permitting easy removal of the appropriate phase from culture tubes. The use of ammonium sulfate coupled with the added specificity of the extraction solvent results in an extract with low background absorption and a well-defined spectrum for the extracted theophylline.

Humans↗
PubMed1976

[Determination of the initial stage of fat auto-oxidation in dry dairy products by ultraviolet spectrophotometry].

Studied were the values of the conjugated dienes using ultraviolet spectrophotometry of fats contained in the dry dairy products produced in this country, such as powdered milk for children, Vitalakt 1, Bébé 1, and Biolakton in the first months of storage. It was found that the extinction maximum values characteristic of the conjugated dienes for the fats of all studied dry milk products were at 227 nm. The juxtaposition of changes taking place with conjugated dienes and peroxide numbers of the fats during storage revealed the greater stability of conjugated dienes in comparison with the hydroperoxides.

Animals↗