Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Spectrophotometry”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed2003

First-order UV-derivative spectrophotometry in the analysis of omeprazole and pantoprazole sodium salt and corresponding impurities.

The first-order UV-derivative spectrophotometry, applying zero-crossing method was developed for the determination of omeprazole (OM), omeprazole sulphone (OMS), pantoprazole sodium salt (PANa), and N-methylpantoprazole (NPA) in methanol-ammonia 4.0% v/v, where the sufficient spectra resolutions of drug and corresponding impurity were obtained, using the amplitudes 1D(304), 1D(307), 1D(291.5) and 1D(296.5), respectively. Method showed good linearity in the ranges (microg ml(-1)): 1.61-17.2 for OM; 2.15-21.50 for OMS; 2.13-21.30 for PANa and 2.0-20.0 for NPA, accuracy and precision (repeatability and reproducibility). The experimentally determined values of LOD (microg ml(-1)) were 1.126; 0.76; 0.691 and 0.716 for OM, OMS, PANa and NPA, respectively. The obtained values of 2.91% w/w for OMS and 3.58% w/w for NPA in the presence of their parent drug, by applying the method of standard additions, point out the usage of the proposed method in stability studies. Zero-crossing method in the first-order derivative spectrophotometry showed the impurity-drug intermolecular interactions, due to the possible intermolecular hydrogen bonds, confirmed by divergences of experimentally obtained amplitudes for impurities OMS and NPA in comparison to expected values according to regression equations of calibration graphs.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2003

Determination of binary mixtures of analgesic and spasmolytic drugs in pure and dosage forms by derivative spectrophotometry.

Binary mixtures of dipyrone and pitophenone hydrochloride are assayed by zero-crossing second- and third-derivative spectrophotometry and by ratio-spectra first- and second-derivative spectrophotometry. In the first method, calibration plots are linear at 266.5 and 302.5 nm (dipyrone, second derivative), and 257 and 286 nm (pitophenone second derivative) and 242 and 278.3 nm (dipyrone third derivative), and 228.5 and 300 nm (pitophenone, third-derivative). By the second method, lines of regression are linear at 235 and 262 nm (dipyrone, first derivative), and 229.5 and 288.5 nm (pitophenone, first-derivative), and 249.7 and 268 nm (dipyrone, second derivative), and 280.5 and 300 nm (pitophenone, second-derivative). In all methods calibration curves follow the Beer's law up to 40 microg/ml of each drug. LOD and LOQ values were calculated. The developed derivative spectrophotometric methods were applied to laboratory mixtures and to vials for these drugs. The procedures are simple, rapid, and did not require any preliminary separation or treatment of the samples.

Analgesics↗
PubMed1998

Simultaneous determination of dextromethorphan HBr and bromhexine HCl in tablets by first-derivative spectrophotometry.

A rapid, simple and direct assay procedure based on first-derivative spectrophotometry, using a zero-crossing and peak-to-base measurement at 234 and 324 nm, respectively, has been developed for the specific determination of dextromethorphan HBr and bromhexine HCl in tablets. Calibration graphs were linear with the correlation coefficients of 0.9999 for both analytes. The limit of detections were 0.033 and 0.103 microgram ml-1 for dextromethorphan HBr and bromhexine HCl, respectively. A HPLC method has been developed as the reference method. The results obtained by the first-derivative spectrophotometry were in good agreement with those found by the HPLC method.

Antitussive Agents↗
PubMed1999

Simultaneous determination of hydrochlorothiazide and amiloride hydrochloride by ratio spectra derivative spectrophotometry and high-performance liquid chromatography.

Rapid, precise, accurate and specific ratio spectra derivative spectrophotometry and high-performance liquid chromatographic procedures were described for the simultaneous determination of hydrochlorothiazide and amiloride hydrochloride in combined pharmaceutical dosage forms. For the first method, ratio spectra derivative spectrophotometry, the signals were measured at 285.7 nm for hydrochlorothiazide and at 302.5 nm for amiloride hydrochloride in the mixture, in the first derivative of the ratio spectra. The second method is based on high-performance liquid chromatography (HPLC) on LiChrosorb RP-C18 column (5 microm, 20 cm x 4.6 mm) using 0.025 M orthophosphoric acid (adjusted to pH 3.0 with triethylamine (TEA)), acetonitrile (84:16 v/v) as a mobile phase at a flow rate of 1.2 ml/min(-1). Detection was carried out using a UV detector at 278.0 nm. Commercial sugar-coated and laboratory-prepared mixtures containing both drugs in different proportions were assayed using the developed methods.

Amiloride↗
PubMed1999

Application of derivative-differential UV spectrophotometry and ratio derivative spectrophotometric determination of mephenoxalone and acetaminophen in combined tablet preparation.

A method is presented for the direct determination of mephenoxalone and acetaminophen in combined pharmaceutical dosage forms without prior separation. The first method, derivative-differential spectrophotometry, comprised of measurement of the difference absorptivities derivatized in the first order (deltaD1) of a tablet extract in 0.1 N NaOH relative to that of an equimolar solution in methanol at wavelengths of 289.6 and 252.6 nm respectively. The second method is based on ratio derivative spectrophotometry. The amplitudes in the first derivative of the ratio spectra at 233.5 and 288.9 nm were selected to determine mephenoxalone and acetaminophen in the mixture. The proposed methods, which give thoroughly comparable data, are simple and rapid, and allow one to obtain precise and accurate results.

Acetaminophen↗
PubMed2000

Determination of nimesulide in pharmaceutical dosage forms by second order derivative UV spectrophotometry.

In this study, nimesulide which has been used as an analgesic, antipyretic and anti-inflammatory agent, was analyzed by using second order derivative UV spectrophotometry. The solvent, the degree of derivation, ranges of wavelength and n-value were chosen in order to optimize the conditions. The concentration of nimesulide in its solutions in ethanol and chloroform were determined between the wavelength ranges of 200 and 500 nm (n = 6, delta lambda = 21) and in the linearity ranges of 2.0-90.0 microg ml(-1) in ethanol and 2.0-50.0 microg ml(-1) in chloroform by using the values obtained from the second derivative UV spectrum of the substance. The developed second derivative UV spectrophotometric method was applied to the pharmaceutical preparations such as tablet, sachet (granule) and suspension. Tablet and sachet were analysed in ethanol while the suspension was analysed in chloroform. The results obtained from derivative UV spectrophotometry were compared with those obtained by using HPLC. It was found that the difference was not statistically important between these methods. It was concluded that developed derivative UV spectrophotometric method was accurate, sensitive, precise, reproducible and could be applied directly and easily to the pharmaceutical preparations.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Optothermistor as a breakthrough in the quantification of lycopene content of thermally processed tomato-based foods: verification versus absorption spectrophotometry and high-performance liquid chromatography.

This study reports on the first use of the "optothermistor" as a novel, precise, fast, and low-cost detector of lycopene in a wide range of commercially available processed-tomato products. The quantitative performance of the new device was evaluated by comparing data obtained to that acquired by conventional methods, namely, absorption spectrophotometry and high-performance liquid chromatography (HPLC); the linear correlation was high (R = 0.98). The variation of data obtained with the optothermistor in a series of consecutive measurements performed with the same loading of the sample was better than 1%. However, the repeatability (RSD 0.5-9.0%, n = 3-5) achieved with the optothermistor by independent analyses (multiple loading) is comparable to that of HPLC and spectrophotometry. Results of the studies performed on the 19 products derived from tomatoes demonstrated that the optothermistor is suitable for selective, accurate, precise, and simple determination of lycopene (range = 7-75 mg/100 g of product weight) without the need for a sample pretreatment step. The estimated sensitivity of the present optothermistor is 2 mg of lycopene/100 g of product.

Carotenoids↗
PubMed1988

Determination of amiodarone hydrochloride in pharmaceutical formulations by derivative UV spectrophotometry and high-performance liquid chromatography (HPLC).

Assay procedures based on derivative ultraviolet spectrophotometry and high-performance liquid chromatography (HPLC) have been developed for the specific determination of amiodarone hydrochloride in pharmaceutical dosage forms. The use of first- and second-order derivative spectrophotometry was found to have suppressed the background absorption from the excipients with comparable accuracy and precision to the reversed-phased HPLC reference method. A conventional UV absorption method (lambda = 242 nm) is subject to possible interference by formulation excipients.

Amiodarone↗
PubMed1989

Analysis of trifluralin and other dinitroaniline herbicide residues by zero-order and derivative ultraviolet spectrophotometry.

The utility of zero-order and first- and second-derivative ultraviolet (UV) spectrophotometry for the identification of benfluralin, trifluralin, isopropalin and oryzalin is discussed. These four herbicides were determined by zero-order and first-derivative UV spectrophotometry, with linear calibration graphs established between 50 and 100 concentration units and limits of detection ranging from 1 to 7 micrograms ml-1. The application of these techniques to the residue analysis of fortified soils and niebe and peanut leaves is described. Trifluralin residues were found to be 6.7, 8 and 1.7 micrograms ml-1 in samples of fortified soils, niebe leaves and peanut leaves, respectively. Isopropalin residues were found to range from 62 to 154 micrograms ml-1 in samples of fortified niebe leaves.

Aniline Compounds↗
PubMed2003

Localized irregularities in hemoglobin flow and oxygenation in calf muscle in patients with peripheral vascular disease detected with near-infrared spectrophotometry.

PURPOSE: Near-infrared spectrophotometry is used to measure flow, concentration, and oxygenation of hemoglobin in arterioles, capillaries, and venules several centimeters deep in tissue. The purpose of this study was to investigate the distribution of flow, concentration, and oxygenation of hemoglobin in calf muscle in patients with documented peripheral arterial occlusive disease (PVD), patients with risk factors for PVD,and healthy younger subjects at rest. METHOD: With a frequency-domain near-infrared spectrophotometer and a specially designed probe, we generated maps at 22 locations simultaneously of hemoglobin flow, concentration, and oxygenation, with the venous occlusion method. Eight legs of 7 patients with diagnosed PVD (PVD group), 10 legs of 8 patients with normal ankle-brachial index but with risk factors for PVD (RF group), and 16 legs of 8 healthy subjects (H group) were studied. RESULTS: Global mean values were significantly (P <.05) different between the three groups for oxygen consumption (PVD group, 0.027 +/- 0.009 mL/100 g/min; RF group, 0.038 +/- 0.017 mL/100 g/min; H group, 0.022 +/- 0.020 mL/100 g/min), venous oxygen saturation (PVD, 59.7% +/- 15.4%; RF, 69.6% +/- 10.5%; H, 80.8% +/- 4.5%), and, at 60 s of venous occlusion, concentration changes in oxyhemoglobin (PVD, 4.48 +/- 3.25 micromol/L; RF, 8.44 +/- 2.33 micromol/L; H, 6.85 +/- 4.57 micromol/L), deoxyhemoglobin (PVD, 3.60 +/- 0.73 micromol/L; RF, 4.39 +/- 1.30 micromol/L; H, 2.36 +/- 1.79 micromol/L), and total hemoglobin (PVD, 8.07 +/- 3.83 micromol/L; RF, 12.83 +/- 2.75 micromol/L; H, 9.21 +/- 6.34 micromol/L). No significant difference was found between the three groups for hemoglobin flow (PVD, 0.92 +/- 0.69 micromol/100 mL/min; RF, 1.68 +/- 0.50 micromol/100 mL/min; H, 1.44 +/- 1.17 micromol/100 mL/min) and blood flow (PVD, 0.45 +/- 0.28 mL/100 g/min; RF, 0.77 +/- 0.21 mL/100 g/min; H, 0.62 +/- 0.50 mL/100 g/min). All parameters featured a distribution dependent on location. CONCLUSION: Mean value for venous oxygen saturation was higher in healthy subjects compared to patients with documented PVD. In patients with PVD, areas of lower oxygenation were clearly discernible. At distal locations of calf muscle, significant correlations between reduced hemoglobin flow, venous oxygen saturation, oxyhemoglobin, and total hemoglobin and reduced ankle-brachial index were found. Maps revealed localized irregularities in oxyhemoglobin, total hemoglobin, and venous oxygen saturation in patients with PVD. Near-infrared spectrophotometry is a noninvasive bedside technique that can enable determination of blood flow and oxygenation in tissue and may provide a method for evaluating patients with PVD.

Adult↗
PubMed1998

Alternative test methods to control the compliance of polyolefin food packaging materials with the European Union regulation: the case of aromatic antioxidants and of bis(ethanolamine) antistatics based on 1H-NMR and UV-visible spectrophotometry.

In order to decide whether a plastic food packaging material complies with the European Communities (EC) regulation on migration, a quick analysis of two functional classes of plastics additives (aromatic antioxidants and antistatic agents) from polyolefin materials by 1H-NMR and UV-visible spectrophotometry is presented. The scope of spectroscopic methods for alternative and migration tests is presented. 1H-NMR can be used in several ways, from a simple fingerprint of the potential migrants to an identification procedure. Extraction is optimized using UV spectrophotometry. Optimization relies on extraction kinetics, which include the demonstration that extraction is more severe than migration. Only a few hours are required to conclude whether a material complies with the regulation. The specific migration limits are expressed as specific absorbance limit values, alpha. These data can be annexed by food industries to specifications of a plastic packaging material.

Antioxidants↗
PubMedDate not supplied

A comparison of spectrophotometry and color charts for evaluating total plasma carotenoids in wild birds.

The study of the role of carotenoids on the physiology and evolutionary ecology of birds demands methods for their quantification in the bloodstream. We compared color-chart scores of plasma hue with the actual concentration of plasma carotenoids obtained by spectrophotometry in 356 wild birds from 26 species. Repeatability of chart scores between three independent observers was high. However, color scores did not correlate with the spectrophotometric results in interspecific analyses. Within species (n = 3), one showed no relationship and two showed weak but significant positive correlations. Hemoglobin, and probably other substances, may mask the color of carotenoids, making the accurate use of color charts difficult. Spectrophotometry should be the method of choice as it permits precise quantifications of total plasma carotenoids and objective comparisons among studies.

Animals↗
PubMed1981

Separation of bilirubin from hemoglobin by recording derivative spectrophotometry.

Recording derivative spectrophotometry is a technic for resolving overlapping absorbance curves by enhancing small changes in those curves. The derivative (slope) is a function sensitive to rapid changes in the curve and will amplify those regions while damping out slowly changing portions of curves. The method presented relies on a mathematical analysis of the composite absorption curve formed by bilirubin and hemoglobin. Data confirming the usefulness of this technic for reliably and quantitatively separating these two substances in aqueous solution are presented. Recording derivative spectrophotometry may be useful for analyzing amniotic fluid, urine, or other biologic fluids.

Bilirubin↗
PubMedDate not supplied

The application of derivative spectrophotometry for the simultaneous determination of cocaine and other local anesthetics.

Part I. Cocaine-Lidocaine Mixtures A rapid procedure based on second-derivative UV spectrophotometry is proposed for the simultaneous determination of cocaine and lidocaine. The optimum magnitudes are chosen in terms of response linearity, sensitivity, relative percent error, relative recovery data, and reproducibility. Part II. Cocaine-Procaine Mixtures A derivative spectrophotometric method based on second-derivative ultraviolet absorption spectra has been developed for the simultaneous determination of cocaine and procaine. Several derivative magnitudes have been investigated. A statistical analysis of the results is reported. Part III. Cocaine-Tetracaine Mixtures A simple method has been developed for the simultaneous determination of cocaine and tetracaine by measuring the amplitudes of the positive peak at 286.6 nm and the negative peak at 313.9 nm with respect to zero baseline. Part IV. Cocaine-Benzocaine Mixtures Derivative ultraviolet spectrophotometry has been used for the simultaneous determination of cocaine and benzocaine. Both cocaine and benzocaine can be assayed by measurement of, respectively, the peak-to-peak amplitude D261.4,277.4 and the peak-to-zero amplitude D299.4. The method is applied to simulated street samples of cocaine.

Anesthetics, Local↗
PubMed1978

Lithium neurotoxicity. I. The concentration of lithium in dopaminergic systems of rat brain determined by flameless atomic absorption spectrophotometry.

Severe neurotoxicity has been reported in patients receiving combinations of lithium and butyrophenones and halogenated phenothiazines and the suggestion has been made that lithium is preferentially concentrated in dopamine systems in brain. Conventional flame atomic absorption spectrophotometry does not allow analysis of sufficiently small samples of brain tissue to allow accurate association with specific transmitter systems, although previous reports have suggested that lithium is concentrated in the striatum. A method has been developed using flameless atomic absorption spectrophotometry to allow accurate measurement of lithium concentrations in 10--100 ng fresh weight of brain tissue. Using this technique in experiments where rats were fed lithium over a period of three weeks, we could not confirm a direct association of lithium with an area predominetly served by dopamine transmitters.

Animals↗
PubMed2001

ACP Best Practice No 166: CSF spectrophotometry in the diagnosis of subarachnoid haemorrhage.

After subarachnoid haemorrhage (SAH), cerebral angiography is usually performed to establish a site of bleeding, which may then be treated surgically to prevent a potentially catastrophic re-bleed. The investigation of choice in the diagnosis of SAH is computerised tomography (CT). However, because CT can miss some patients with SAH, cerebrospinal fluid (CSF) spectrophotometry should be performed in those patients with negative or equivocal CT scans or those who have presented several days after the suspected bleed. Spectrophotometry should aim to detect the presence of both oxyhaemoglobin and bilirubin because either one or both of these pigments may contribute to xanthochromia following SAH. CSF supernatant is scanned using a double beam spectrophotometer at wavelengths between 350 nm and 650 nm. Oxyhaemoglobin alone produces an absorption peak at 413-415 nm, bilirubin alone produces a broad peak at 450-460 nm, and bilirubin together with oxyhaemoglobin produce a shoulder at 450-460 nm on the downslope of the oxyhaemoglobin peak. To minimise the frequency of false positive and false negative results, a protocol has been developed, which is described.

Bilirubin↗
PubMed1974

Spectrophotometry of cerebrospinal fluid in subacute and chronic subdural haematomas.

Spectrophotometric examinations were performed on cerebrospinal and subdural fluids in subacute (five patients) and chronic (20 patients) subdural haematomas, with special reference to the diagnostic aid of CSF spectrophotometry. Spectrophotometric xanthochromia of haemorrhagic origin was found in all CSFs examined, while definite visible xanthochromia was observed in only 28% and the CSF was judged as colourless in 52% of those cases. Characteristic bleeding patterns were found spectrophotometrically in all the 20 CSFs examined within 24 hours after lumbar puncture, haematoma patterns being detected in 90-95% of the cases. In many cases the electrophoretically separated protein fractions of CSF and subdural fluids were spectrophotometrically examined. In conclusion, CSF spectrophotometry is a simple, fast, and extremely sensitive method, which in our opinion should be used routinely in the diagnosis of suspected subdural haematomas, if lumbar puncture is not contraindicated.

Adolescent↗
PubMed1978

Determination of urinary manganese by the direct chelation-extraction method and flameless atomic absorption spectrophotometry.

The direct chelation-extraction method, originally developed by Hessel (1968) for blood lead analysis, has been successfully applied to urinalysis for manganese. The analyses of 35 urine samples containing up to 100 microgram/1 of manganese from manganese-exposed workers showed that the data obtained by this method agree well with those by wet digestion-flame atomic absorption spectrophotometry and also by flameless atomic absorption spectrophotometry.

Chemical Industry↗