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At least 865 records · Page 48Linked to original sources
PubMed1975

Binding study of sulfonylureas and phenothiazines to bovine serum albumin using difference spectrophotometry.

2-(4'-Hydroxybenzeneazo)benzoic acid is a spectrophotometric probe which shows absorption spectrum changes upon binding to protein. Difference absorption spectra of this probe were used as an indirect measurement of the binding of selected sulfonylurea and phenothiazine drugs to bovine serum albumin. The results obtained using the spectrophotometric probe were similar to data obtained from other methods, especially fluorescent methods. Of the four sulfonylureas studied, tolbutamide showed the highest binding affinity, followed by glyburide, glipizide, and acetohexamide, in that order. The data collected for phenothiazine drugs indicated that chlorpromazine has the highest affinity, followed in order by trifluoperazine, perphenazine, fluphenazine, and promazine. Correlation of these results with chemical composition indicated that the interaction of phenothiazine drugs with bovine serum albumin was of a hydrophobic nature.

Animals↗
PubMed1977

Spectrophotometry as a tool for assaying endotoxins.

A spectrophotometric method is reported for assaying endotoxins over a wide concentration range, including low parts per billion levels. Five solution of endotoxins. Escherichia coli 0127:B8, Escherichia coli 055:B5, Salmonella abortus-equi, Salmonella enteritidis, and Shigella flexneri, were examined. Each exhibited an absorption maximum at 259 nm, but the absorptivities differed in each case. Thus, rigorous quantification requires that the identity of the endotoxin be known. The uv absorbance and the statistical data for the standard curves for three groups of standard solutions are presented. The absorbance for each group was linear with concentration within acceptable limits.

Endotoxins↗
PubMed1980

Aspirin--a national survey III: Determination of impurities in bulk aspirin and aspirin formulations by high-pressure liquid chromatography and spectrophotometry.

A quantitative high-pressure liquid chromatographic method, using a reversed-phase column and an aqueous acetic acid-methanol solution as the mobile phase, was employed for the determination of O-acetyl-O-salicylsalicylic acid and O-salicylsalicylic acid in pharmaceutical aspirin preparations. The aspirin was dissolved, filtered, and injected into the chromatograph. The absorbance of the impurities was measured at 254 nm. Acetylsalicylic anhydridge was determined by a spectrophotometric method. The aspirin was dissolved in pH 11.3 buffer and extracted with benzene. An aliquot of the benzene was evaporated, and the residue was dissolved in alpha-benzamidocinnamate-pyridine reagent. The acetylsalicylic anhydride was measured using the difference between the absorbance at 362 and 372 nm. Possible interference of aspirin with the procedure is discussed. Thirty-four bulk aspirin and 172 tablet formulations were examined. Results for O-acetyl-O-salicylsalicylic acid, O-salicylsalicylic acid and acetylsalicylic anhydride are given.

Aspirin↗
PubMed1981

Determination of platinum in serum and ultrafiltrate by flameless atomic absorption spectrophotometry.

A graphite furnace atomic absorption spectrophotometric assay, capable of accurately determining nanogram amounts of platinum in serum and ultrafiltrate, was developed. A sample serum or ultrafiltrate was acidified with nitric acid and heated to destroy the protein-platinum bond. A measured excess of ammonium 1-pyrrolidinedithiocarbamate was added, and the platinum complex was extracted into isopropylacetone. The extract was injected into the graphite furnace. The sample was dried, charred, and atomized using optimal conditions. The resulting absorbance was used to determine the platinum content.

Humans↗
PubMed1981

Analysis of pilocarpine and isopilocarpine in ophthalmic solutions by UV spectrophotometry-polarimetry.

An improved analytical method was developed that simultaneously quantitates pilocarpine and isopilocarpine in the presence of each other and pilocarpic acid. Pilocarpine and isopilocarpine are first separated from any pilocarpic acid present in the sample by eluting with water-washed chloroform through a column packed with acid-washed diatomaceous earth. The concentrations of pilocarpine and isopilocarpine then are determined by a combination of UV spectrophotometric and polarimetric measurements. UV absorbance is measured at the absorption maximum (215 nm), and optical rotation is measured at the 254-nm line of mercury. Standard curve and standard recovery data are presented. The method is applicable to several commercially available ophthalmic solutions of pilocarpine and is compared to both the USP colorimetric method and a high-performance liquid chromatographic method.

Magnetic Resonance Spectroscopy↗
PubMed1984

Assay of chlordiazepoxide and demoxepam in chlordiazepoxide formulations by difference spectrophotometry.

Rapid difference spectrophotometric methods for chlordiazepoxide and demoxepam in chlordiazepoxide formulations are described which overcome the nonspecificity of the official spectrophotometric assays. The procedures are based on the measurement of the difference absorbance at 269 nm of equimolar solutions of chlordiazepoxide at pH 8 and pH 3 and the difference absorbance at 263 nm of equimolar solutions of demoxepam at pH 13 and pH 8. The methods are specific for chlordiazepoxide and demoxepam in the presence of both compounds, 2-amino-5-chlorobenzophenone, certain coformulated drugs, and formulation excipients. Analyses of commercial dosage forms of chlordiazepoxide have shown the presence of demoxepam at concentrations in excess of the pharmacopoeial specifications in some aged samples.

Anti-Anxiety Agents↗
PubMed1984

Assay of benzenoid drugs in tablet and capsule formulations by second-derivative ultraviolet spectrophotometry.

Rapid second-derivative assay procedures are described for tablet and capsule formulations of benzenoid drugs, which eliminate the interference of the formulation excipients in simple UV spectrophotometric methods. Accuracy, precision, and selectivity of the technique are discussed. The general application of the procedures for the batch assay of tablet and capsule dosage forms containing greater than or equal to 2 mg of a benzenoid drug is indicated by the results obtained for 18 such formulations, in good agreement with pharmacopeial assay results and/or declared amounts. The procedures are sufficiently sensitive to permit unit dose assays of these formulations.

Benzene Derivatives↗
PubMed2005

Extraction and determination by liquid chromatography and spectrophotometry of naloxone in microparticles for drug-addiction treatment.

This paper discusses the development and validation of two analytical methods for the assay of naloxone in microparticles, as used in the therapy of opioid drug addiction (weaning). A UV-Vis spectrophotometric method is proposed to study drug loading and drug release, due to its ease and simplicity of performance, while a high performance liquid chromatographic method is developed as a means of stability-indication. Both analytical procedures were validated according to the International Committee for Harmonization (ICH) guidelines. Although the ranges and wavelengths were different for the two analytical methods, they were both found to be specific, linear, precise, and accurate under the determined conditions.

Chromatography, High Pressure Liquid↗
PubMed1993

Different structure of the complexes of two cytochrome P-450 isozymes with acetanilide by 1H-NMR relaxation and spectrophotometry.

The functional and spectral characteristics of the interaction of acetanilide with phenobarbital- and methylcholanthrene- induced rat liver microsomes, as well as with corresponding major isozymes (cytochromes P-450b and P-450c) have been compared. The magnitude of the reverse 1st type binding spectra proved to be negatively correlated with the acetanilide oxidation on isozymes under study. The data on paramagnetic relaxation of acetanilide protons in the presence of P-450 have shown the structure of the enzyme-substrate complex to be different for two isozymes, acetanilide molecule being closer to Fe ion in the active site in the case of P-450c, which is active towards acetanilide oxidation. For the P-450c-acetanilide complex the group oxidized (phenyl) is the closest to Fe ion.

Acetanilides↗
PubMed2002

ICG pulse spectrophotometry for perioperative liver function in hepatectomy.

BACKGROUND: The indocyanine green (ICG) clearance test has been used to estimate liver functional reserve before hepatectomy. However, changes in ICG clearance after hepatectomy have not been investigated, and their extent remains unknown. PATIENTS AND METHODS: The ICG(K) value, signifying the ICG elimination rate constant, was measured with pulse-dye densitometry before operation and 1, 2, 3, 5, and 7 days postoperatively in 22 patients who underwent liver resection of various extent. CT volumetry was used to calculate the residual liver volume ratio. The relationship between the pre- and postoperative ICG(K) value and the residual liver volume ratio was examined statistically. RESULTS: There was a significant drop in ICG(K) value, from 0.193 +/- 0.011 before operation to 0.160 +/- 0.013 on Postoperative Day 1, and then it remained significantly low at the postoperative examination times. The residual liver volume ratio was 70.2 +/- 5.4%. The estimated ICG(K) value, calculated by the preoperative ICG(K) value and the residual liver volume ratio, showed a significant correlation with the actual postoperative value (r = 0.859 on Postoperative Day 1, P < 0.0001). In five patients with prolonged jaundice, the estimated ICG(K) value was significantly lower than in those without it (0.077 +/- 0.028 versus 0.153 +/- 0.012, P = 0.0136). CONCLUSIONS: The perioperative ICG(K) value measured by pulse-dye densitometry revealed a significant decrease in ICG(K) after operation depending on the reduction in liver volume, and the estimated ICG(K) based on the residual liver volume was useful in predicting postoperative morbidity.

Adult↗