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Results for “Spectrophotometry, Ultraviolet”

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PubMed1976

High-pressure liquid chromatographic determination of vitamin D3 in resins, oils, dry concentrates, and dry concentrates containing vitamin A.

A high-pressur liquid chromatographic (HPLC) procedure has been developed for the determination of vitamin D3 in resins, oils, dry concentrates, and dry concentrates containing vitamin A. Specificity of the method for vitamin D3 in the presence of isomers and other related constituents was shown by ultimate recovery of the vitamin D3 and the individual constituents and their characterization by other methods such as ultraviolet spectrophotometry. Precision and accuracy are within 2%, and as many as 20 determinations may be completed in a working day. Excellent agreement with the official AOAC biological assay was found. A comparison of the response of isomers of vitamin D3 by the HPLC method vs. other instrumental and chemical procedures shows HPLC to be the most specific method for determining the bioactive isomers.

Chemical Phenomena↗

PubMed1991

[Fluorescent determination of magnolol by surfaceactive emulsifier].

Fluorescent determination of magnolol has been effected employing the sensitivity- and stability-enhancing action of the non-ionic surfaceactive emulsifier OP. As a result the accuracy of determination is raised by 2 orders of magnitude as compared to that of ultraviolet spectrophotometry.

Biphenyl Compounds↗

PubMed1991

[Reports on medico-legal data from the massive-investigation performed by the Medico-Legal Society of Japan--a statistical study of death by poisoning. Investigation Committee of the Medico-Legal Society of Japan].

A statistical study was made on the fatal poisoning cases examined by forensic pathologists in Japan, in the period of 1975-1984. The total number of the cases was 1559:29.9% were poisoning by carbon monoxide, 10.9% by the other gases (cyanide, liquefied petroleum gas, hydrogen sulfide and freon), 10.9% by alcohol (mean blood ethanol level was 4.27 mg/ml), 9.3% by medicines (bromvalerylurea, barbiturates, chlorpromazine etc.), 9.2% related to burning (mean CO-Hb level was 47.9%), 7.4% by pesticides (organophosphate, paraquat, carbamate, chlorinated hydrocarbon etc.), 3.5% by methamphetamine and 11.2% by the others, including 4.9% by oxygen deficiency. These cases were found most frequently in winter and 41% of the victims died within 30 minutes after ingestion or inhalation. With regard to age distribution, the peak of frequency was 41 to 45 in male, and not characteristic in female. Samples were mainly the blood, urine and stomach contents, and analyzed by gas chromatography, spectrophotometry, ultraviolet spectrometry, thin-layer chromatography, atomic absorption spectrometry and gas chromatography-mass spectrometry.

Adolescent↗

PubMed1990

[Quality control of cod liver oil, physicochemical methods of analysis].

The control of oils and fats requires analytical processes far surpassing the traditional framework of physical properties and chemical characteristics. The control of cod liver oil is improved by the use of these procedures. The present report is devoted to the measurement of vitamin A by ultraviolet spectrophotometry and of vitamin D3 by high performance liquid chromatography, to the determination of the profile of their fatty acids and polyunsaturated fats, as well as to their measurement by liquid gas chromatography after derivatisation. The results permit the definition of the cod liver oil's quality, the differentiation between fish oils and the detection of possible changes. A technique for verifying the absence of butylhydroxyanisol and of butylhydroxytoluen is also described.

Chemistry Techniques, Analytical↗

PubMed1978

Assay of vitamins D2 and D3, and 25-hydroxyvitamins D2 and D3 in human plasma by high-performance liquid chromatography.

I describe a new assay that is capable of measuring vitamin D2, vitamin D3, 25-hydroxyvitamin D2, and 25-hydroxyvitamin D3 in 2 ml of plasma or serum. Plasma is extracted by the Bligh and Dyer technique [Can. J. Biochem. Physiol. 37, 911 (1959)], the lipid component is fractionated by two high-performance liquid-chromatographic systems based upon adsorption and reversed-phase chromatography, and each of the four vitamin D metabolites is measured by its absorbance at 254 nm. The method has a sensitivity limit of 0.5 mug/liter of plasma. The identity of metabolite peaks was confirmed by mass spectrometry, ultraviolet absorption spectrophotometry, and rechromatography, and there was good correlation (r=0.84) between plasma 25-hydroxyvitamin D as measured by the present method and by a protein binding assay developed in our laboratory. Mean concentrations of vitamin D and 25-hydroxyvitamin D in normal adults (n=25) in December were 2.2 +/- 1.1 (SD) and 16 +/- 3.9 (SD) mug/liter, respectively. 25-Hyroxyvitamin D2 made up 31% of the total 25-hydroxyvitamin D. Patients receiving pharmacological doses of vitamin D had values for vitamin D and 25-hydroxyvitamin D that were 10- to 100-fold normal. This method provides a rapid, reliable physico-chemical assay that appears to have advantages over existing protein binding assays and can be used to measure circulating vitamin D.

Adult↗

PubMed1975

Drug diffusion and bioavailability: tetracycline metallic chelation.

The effects of chelation on the in vitro diffusion rate of tetracycline at variable pH values and concentrations was studied. A two-compartment diffusion cell using a semipermeable cellophane membrane was used to determine diffusion rates. Tetracycline in solution was mixed with aluminum, magnesium, copper, calcium and cobalt ions and analyzed by ultraviolet spectrophotometry. Diffusion rates were determined at pH 1, 5.5 and 8. Tetracycline chelate formation is pH-dependent. The diffusion rate of tetracycline chelates is concentration-dependent and is reduced even if the chelate is water soluble.

Biological Availability↗

PubMed1989

Evaluation of five procedures for measuring nonstandard doses of nifedipine liquid.

Five methods for removing the maximum volume of liquid from a nifedipine capsule were evaluated for efficiency and reproducibility, and the concentration of nifedipine in Procardia and Adalat 10- and 20-mg capsules was determined The methods evaluated were the needle puncture and squeeze method; the scissors method; the needle and syringe, one-hole method; the needle and syringe, two-hole method; and the capsule in syringe barrel method. The liquid content of 10 Adalat 10-mg capsules was removed by each method, the volume was determined by the weight and specific gravity of the nifedipine liquid, and the mean volumes of nifedipine liquid were compared. A stepwise procedure for using the needle and syringe, one-hole method was developed. The mean nifedipine concentration in Procardia 10- and 20-mg capsules was determined by ultraviolet spectrophotometry by using 30 capsules of each brand and strength. The needle and syringe methods were the most reproducible and efficient procedures for obtaining a desired milligram dosage of nifedipine from the capsules. The two-hole method would be less practical in the clinical setting, however, because it is time consuming and cumbersome. The mean assayed nifedipine concentration in the Procardia and Adalat 10- and 20-mg capsules was within 10% of the concentration reported by the manufacturer for each specific product lot number. Based on reproducibility and efficiency, the needle and syringe methods are the best methods for quantitation of liquid nifedipine doses for patient administration.

Capsules↗

PubMed1977

High-pressure liquid chromatography as a tool for determination of antibiotics in biological fluids.

The toxicity of some antibiotics used today necessitates rapid, specific and accurate determinations of antibiotic concentrations in biological fluids. Microbiological assays do not fulfill these needs and new procedures have recently been developed, for instance, fluorimetric assays, radioimmunoassays and radioenzymatic assays. However, these techniques have not been generally applicable to various antimicrobial agents. - The technique for high-pressure liquid chromatography (HPLC) has recently been applied to determination of antibiotics in biological fluids. The methods involve extraction of drug from the biological samples, separation by HPLC and detection by ultraviolet spectrophotometry of fluorimetry. Results obtained with tetracycline, amphotericin B, and cephalothin show that this procedure meets the demands for rapid, specific and accurate monitoring of antibiotic concentrations in body fluids. Because of its versatility, the HPLC technique seems to be applicable to the determination of a variety of antibiotics and other drugs in clinical and experimental medicine.

Anti-Bacterial Agents↗

PubMed1988

NAD+-dependent oxidation of 20-hydroxyleukotriene B4 to 20-carboxyleukotriene B4 by rat liver cytosol.

20-Hydroxyleukotriene B4 was converted by rat liver homogenates in the presence of NAD+ to a more polar product on reverse-phase high-performance liquid chromatography. The product was identified as 20-carboxyleukotriene B4 by straight-phase high performance liquid chromatography, ultraviolet spectrophotometry and gas chromatography-mass spectrometry. The oxidative activity of the homogenates was located in the cytosol with an optimal pH of 8.0. The activity was dependent on NAD+, and NADP+ could not substitute for NAD+. 1 mol of 20-carboxyleukotriene B4 was formed with the reduction of 2 mol of NAD+. The reaction was inhibited by pyrazole and 4-methylpyrazole, inhibitors of alcohol dehydrogenase, and by various alcohols, such as ethanol, 12-hydroxylaurate, and 20-hydroxyprostaglandin E1. Disulfiram, an inhibitor of aldehyde dehydrogenase, also inhibited the activity. These results suggest that two discrete steps catalyzed by different enzymes, alcohol dehydrogenase and aldehyde dehydrogenase, are involved in the oxidation of 20-hydroxyleukotriene B4 in rat liver cytosol. The enzyme system seems to be different from that of human neutrophils.

Animals↗

PubMed1986

Sorption of four drugs to polyvinyl chloride and polybutadiene intravenous administration sets.

Sorption of nitroglycerin, isosorbide dinitrate, diazepam, and clomethiazole edisylate (chlormethiazole) to polyvinyl chloride (PVC) i.v. administration sets with and without cellulose propionate burettes and to polybutadiene (PBD) sets with and without methacrylate butadiene styrene (MBS) burettes was studied. All drugs (except chlormethiazole) were diluted with 0.9% sodium chloride injection (NS) in glass bottles or in the burette chambers. Initial samples of each solution were obtained from the bottle or from the burette, and effluent samples were collected at various times up to 240 minutes from the sets without burettes and up to 90 minutes from the sets with burettes. For nitroglycerin, flow rates of 0.5 and 1.0 mL/min were used without the burette. The effect of priming the tubing before adding drug to the burette was studied for diazepam. Triplicate samples were analyzed for nitroglycerin and isosorbide dinitrate by high-performance liquid chromatography and for diazepam and chlormethiazole by ultraviolet spectrophotometry. Up to 50% potency of chlormethiazole and nitroglycerin, 15-25% of isosorbide dinitrate, and 13-20% of diazepam was lost to PVC sets without burettes, and an additional 10-15% loss of each drug resulted when PVC sets with burettes were used. Less sorption of nitroglycerin to the PVC sets occurred at the higher flow rate, but flow rate through the PBD sets did not affect sorption. Priming the tubing before adding diazepam to the burette did not affect final drug delivery. No loss to PBD sets was observed for nitroglycerin, isosorbide dinitrate, and diazepam; loss of chlormethiazole to PBD was 7-13%. Drug potency in effluent from PBD sets was not affected by presence or absence of a burette.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗

PubMed1979

Cefoxitin sodium compatibility with intravenous infusions and additives.

The compatibility and stability of cefoxitin sodium in solution with a series of frequently used intravenous infusion fluids and injectable additives were studied. Cefoxitin sodium's stability in various solutions was measured by ultraviolet spectrophotometry, iodometry, thin-layer chromatography, high-pressure liquid chromatography, ion-exchange chromatography and microbiological assay. Cefoxitin sodium was shown to maintain 90% of its initial concentration in aqueous solution for 40 hours at room temperature (25 C) and about 30 days at 5 C. The stability of cefoxitin sodium in common i.v. infusion fluids was independent of the concentrations (1 mg/ml to 400 mg/ml) and containers used, and was retained after 30 weeks storage at -20 C. Similar stability patterns were demonstrated for cefoxitin sodium in protein hydrolysate solutions and multivitamin formulations. Cefoxitin sodium was chemically and visually compatible with amikacin sulfate, gentamicin sulfate, kanamycin sulfate and tobramycin sulfate when admixed with normal saline or 5% dextrose in water injections. Cefoxitin sodium (397 mg/ml) in 0.5% lidocaine hydrochloride was stable after 26 weeks of storage at -20 C. Sodium cefoxitin is compatible with a wide variety of commonly used infusion solutions. Its stability is independent of concentration or pH within the ranges studied, and of types of common containers.

Aminoglycosides↗

PubMed1987

Fundamental properties of local anesthetics. I. The dependence of lidocaine's ionization and octanol:buffer partitioning on solvent and temperature.

The protonation equilibrium and hydrophobic character of lidocaine were characterized by its pKa and the octanol:buffer partition coefficients of the charged (P+) and neutral (Po) drug species. These measurements were accomplished by ultraviolet spectrophotometry of pure lidocaine HCl solutions at different temperatures, ionic strengths, and buffer concentrations. Corroboration of the pKa determination by the potentiometric method and of the partition coefficients by gas chromatography validated the general application of the spectrophotometric technique. The pKa increased with decreasing temperature (7.61 +/- 0.06 at 36 degrees C; 7.94 +/- 0.04 at 26 degrees C, in water; mean +/- SD), increasing ionic strength (8.06 +/- 0.02 at 26 degrees C in 0.165 M NaCl) and increasing buffer capacity (8.28 +/- 0.06 at 25 degrees C in 0.15 M NaCl + 20 mM buffer). Octanol:buffer partition coefficients for both the protonated and the neutral species (expressed as mole fractions) increased upon warning: 0.55 +/- 0.04 and 2666 +/- 202, respectively, at 25 degrees C, and 0.75 +/- 0.09 and 3210 +/- 272, respectively, at 36 degrees C. Ionic strength and buffer concentration had no significant effect on either P value. The increase in pKa at lower temperatures coupled with the decreased partition coefficients resulted in a nearly constant concentration of the protonated species in octanol as the system was cooled, whereas the concentration of the neutral species fell by more than 80%. This finding may explain the large increase in the impulse blocking potency of lidocaine observed upon nerve cooling, if the protonated anesthetic species is the more active form of the drug competing with the neutral species for a common binding site.

1-Octanol↗

PubMed1985

The metabolic transformations of columbinic acid and the effect of topical application of the major metabolites on rat skin.

The metabolism of columbinic acid by various fatty acid oxidizing enzyme systems was studied. A cyclooxygenase product, 9-hydroxy-(5E,10E,12Z)-octadecatrienoic acid, was formed nearly quantitatively by ram seminal vesicle microsomes and in small amounts by washed human platelets. The major lipoxygenase product from washed human platelets, soybean lipoxygenase, and neonatal rat epidermal homogenate was 13-hydroxy-(5E,9Z,11E)-octadecatrienoic acid, although lesser quantities of other isomers differing in the double bond configurations were also identified by ultraviolet spectrophotometry and gas chromatography-mass spectroscopy. Topical application of the major lipoxygenase product to paws of essential fatty acid-deficient rats resulted in nearly as complete resolution of the scaly dermatitis as did the application of columbinic acid itself; the cyclooxygenase product was not at all effective.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed1986

Localization of the structural difference between bovine blood coagulation factors X1 and X2 to tyrosine 18 in the activation peptide.

Bovine Factor X is isolated in two chromatographically separable forms, Factor X1 and Factor X2. Whereas only a single form of Factor Xa, the active protease, exists, the activation peptides also exist as two chromatographically distinct species. These peptides have been shown to differ at a tyrosyl residue by ultraviolet spectrophotometry, and in their composition after alkaline hydrolysis. On the basis of the spectral properties, and elution position of the modified tyrosine on Dowex 1 columns and on an amino acid analyzer, it has been concluded that Factor X2 contains a tyrosyl-O-SO4 residue at position 18 in the activation peptide whereas Factor X1 contains only tyrosine. Alternative explanations such as differences in carbohydrate composition, differences in phosphate content, or differences in the number of gamma-carboxyglutamic acid residues were demonstrated to be unrelated to the difference in chromatographic behavior between bovine Factors X1 and X2.

Amino Acids↗

PubMed1986

Determination of vanillylmandelic acid with ion-pair chromatography and fluorescence detection.

We describe a chromatographic procedure for sensitive (2.0 mumol/L), specific quantification of vanillylmandelic acid (VMA) in urine with iso-VMA as an internal standard. After rapid extraction from urine, the VMA is determined by isocratic reversed-phase ion-pair chromatography on a bonded C8 column and detection of the native fluorescence on excitation at 285 nm. The fluorescence signal is quite dependent on the pH of the mobile phase. Results by the method vary linearly with VMA concentration up to 320 mumol/L and correlate well (r = 0.9880) with those obtained by conventional ultraviolet spectrophotometry. The mean 24-h excretion of VMA from 29 healthy volunteers was 21.4 (SD 5.4) mumol.

Adolescent↗

PubMed1985

Thin layer chromatography and high pressure liquid chromatography of musk ambrette and other nitromusk compounds including photopatch studies.

For qualitative and quantitative analysis of musk ambrette and 4 other nitromusk compounds (musk ketone, moskene, musk tibetine, musk xylene) thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC) techniques were developed. By TLC a reasonable separation was obtained and the limit of detection was 2-5 x 10(-7) g. By HPLC the separation was even better and the limit of detection for musk ambrette was 2 x 10(-9) g. The correlation between the amount of musk ambrette/ketone and the HPLC peak was linear. The TLC and HPLC techniques were used to demonstrate the presence of nitromusks in several commercial products, mainly aftershave lotions and eau-de-toilettes preparations. By ultraviolet spectrophotometry, absorption spectra were studied for the nitromusk compounds. The absorption maximum for musk ambrette was at 264 nm, that for moskene at 253 nm. Photopatch testing was carried out in 13 patients photoallergic to musk ambrette. Only 3 patients also reacted to other nitromusks. Photoallergey to musk ketone and musk tibetine is reported for the first time.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

Metabolism and biliary excretion of benzo[a]pyrene 4,5-oxide in the rat.

The excretion and biliary metabolites of intravenously administered benzo[a]pyrene 4,5-oxide were studied in the rat at two dose levels. After administration of 4.5 or 0.47 mumol, half of the dose was excreted in the bile in 60 min. Biliary metabolites were separated by reverse-phase high-pressure liquid chromatography and identified by cochromatography with biosynthetic standards, beta-glucuronidase hydrolysis, ultraviolet spectrophotometry and, in the case of the thioether conjugates, identification of the constituent amino acids. The major biliary metabolite was a mixture of isomeric glutathione conjugates. Some cysteine conjugate was also present, but no cysteinylglycine conjugate was detected. Hydration to transbenzo[a]pyrene-4,5-dihydrodiol followed by glucuronidation was also a quantitatively important metabolic pathway. Although benzo[a]pyrene-4,5-dihydrodiol glucuronide was more readily excreted by the liver than was benzo[a]pyrene 4,5-oxide:glutathione conjugate, the rate of glucuronidation of the dihydrodiol was low, resulting in its accumulation in the liver and possible release into the circulation. Therefore, the glutathione S-transferases may provide a more efficient mechanism for the removal of benzo[a]pyrene 4,5-oxide from the body than is provided by expoxide hydrolase.

Animals↗

PubMed1976

Diazepam abuse: incidence, rapid screening, and confirming methods.

We studied 2500 patients suspected to be drug-overdose victims. Blood samples were quantitatively screened for the most commonly abused drugs, including diazepam. Of these, 61% had positive findings, including diazepam in about one of every four. A new rapid, simple, and quantitative gas-chromatographic method for simultaneous analysis of diazepam and sedatives (in two instruments) is described. A single extraction at low pH is used, preserving the balance of the sample to be used for confirming methods via ultraviolet spectrophotometry and thin-layer chromatography. Prevalance of other positive findings is also listed, and findings for diazepam are categorized by age.

Adolescent↗