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At least 415 records · Page 23Linked to original sources
PubMed1998

Resazurin reduction assay for ram sperm metabolic activity measured by spectrophotometry.

Resazurin (7-hydroxy-3H-phenoxazin-3-one 10-oxide) is a redox dye that can be reduced by metabolically active spermatozoa to resorufin and manifested as visual color change from blue (resazurin) to pink (resorufin). This study combined the resazurin reduction test with spectrophotometric methods and investigated the correlation between metabolic activity and fertilization potential of spermatozoa, using ram semen as a model. The absorbance at specific wavelengths of resazurin and resorufin was determined by scanning photo spectrometer (600 nm for resazurin and 570 nm for resorufin, respectively). The absorbance at wavelengths of 600 nm (A600) and 570 nm (A570) was measured by spectrophotometry and used to evaluate sperm metabolic activity. A600 decreased and A570 increased in relationship to the increased concentrations of motile spermatozoa and increased resazurin reaction times. We observed, upon using a retrospective experimental design, that fertile rams had greater relative absorbance values than rams with lower fertility. Also, we observed a wide range variation of absorbance between the fertile rams, which is highly correlated to the sperm motility. We conclude that the spectrophotometric measurement of resazurin reduction for sperm activity might be a good assay for ram fertility.

Animals↗
PubMed1978

Determination of zirconium in natural water by spectrophotometry following the concentration step with yield tracer.

Zirconium in natural water samples was determined spectrophotometrically after concentration using95Zr as a yield tracer. Acidified sample (1l) with a known amount of 95Zr was evaporated to dryness, treated with hydrofluoric and nitric acids, and then with nitric and perchloric acids, and evaporated nearly to dryness. The residue was taken up with 2 M perchloric acid and zirconium in the solution was extracted with 0.1 M thenoyltrifluoroacetone (TTA) in benzene. The TTA complex solution was converted to hydrochloric acid solution. After the recovery yield was estimated by measuring the radioactivity of 95Zr in the final solution, zirconium was then determined by spectrophotometry with Arsenazo III. Zirconium contents in lake and hot and cold spring samples from Nikko and Shiobara districts were found to be 0.29-2.8 microgram/l by this method.

Fresh Water↗
PubMed2005

Analysis of mercury in sportfish tissue by thermal decomposition, amalgamation/atomic absorption spectrophotometry.

Sportfish samples (n = 133) that originated from Indiana waters were analyzed for total mercury using inductively coupled plasma/mass spectrometry (ICP/MS) and thermal decomposition, amalgamation/atomic absorption spectrophotometry (TDA/ AAS). Total mercury concentrations obtained by the two methods were not significantly different (P > 0.05). The correlation coefficient for total mercury obtained for the two methods was 0.94. The limit of detection using TDA/AAS was 0.1 ppm. TDA/AAS is a preferred technique for the analysis of total mercury in fish tissue because it is rapid (6 min per sample) and easy to use and requires little sample preparation.

Animals↗
PubMedDate not supplied

Determination of selenium in meat products by hydride generation atomic absorption spectrophotometry.

Wet digestion using a mixture of nitric, sulfuric, and perchloric acids and an aluminum block digester effectively and rapidly decomposed meat samples for selenium determination by hydride generation atomic absorption spectrophotometry. Digestion did not require constant attention by an operator. Selenium recoveries (range, 94-105%) from National Institute of Standards and Technology standard reference materials and spiked samples were used to validate method accuracy. Coefficients of variation (CVs) of repeatability of in-house reference materials used for precision study were 6.4 and 5.6%, respectively, for seafood mix and mutton liver. Selenium levels in meat products from Brisbane markets varied widely: 0.042-0.142, 0.081-0.42, and 0.050-0.198 microgram/g (wet weight) respectively, for beef, chicken, and pork. Overall, selenium levels in manufactured meat ranged from 0.041 to 0.189 microgram/g. The levels of selenium found in this study were generally lower than those reported in Finland but comparable with those reported in some parts of the United States.

Animals↗
PubMedDate not supplied

Use of microwave digestion and atomic absorption spectrophotometry to determine chromic oxide as a digestibility marker in feed, feces, and ileal content.

Most conventional digestion procedures, such as dry ashing and wet ashing, are tedious and labor intensive. Microwave digestion is a good alternative, because microwave dissolution is faster, safer, and simpler, and provides more controlled reproducible conditions than conventional methods. The purpose of this study was to develop a microwave digestion method for mineralizing meat and bone meal diets, feces, and ileal contents. Each sample was heated on a hot plate for 10 min, dry ashed at 65 degrees C for 4 h, and transferred into microwave vessels. Then, 10 mL 70% HNO3 was added. Samples were digested for 7, 10, and 20 min at 95, 90, and 85% power, respectively. After the heating cycle, 6 mL 30% H2O2 was added, and samples were returned to the microwave for a second heating cycle of 1 and 7 min at 95% and 90% power, respectively. Finally, chromium concentration was determined by flame atomic absorption spectrophotometry. The digestion method was validated by using a standard reference material, SRM domestic sludge 2781, with a certified chromium value of 195 +/- 9 micrograms/g. The value obtained in this study was 178 +/- 11 micrograms/g, for a difference of 17 micrograms/g. Spike recovery experiments resulted in 103.16 and 100.35% recoveries of chromium from diet and feces samples, respectively. Coefficients of variation were 10.8 and 7.8%, respectively.

Animal Feed↗
PubMed1999

Atomic absorption spectrophotometry (AAS) for the evaluation of metallosis in prostheses and artificial organs: a new approach.

To study the presence of metals in body fluids and tissues after implantation of metallic biomaterials and possible related diseases, a new approach in Atomic Absorption Spectrophotometry (AAS) was developed. This technique was compared to three traditional methods: mineralisation with acid digestion (method A) also known as "wet method", dry ashing (with or without oxygen) (method B); classic Kjeldaal (method C). The new approach (method D) modifies the mineralisation phase and the instrument operating instructions. Al, Na, Cr, K, Ni, Co, Ti, Fe, Hg, Pb, V, Sb and Cu levels were tested with the four methods on bone, muscle, cartilage, skin, brain, lymph nodes, blood, urine, and hair. Test results were checked by the addition method. Results demonstrated a significantly higher percentage of Al, Cr, Ni, Ti and Hg recovery with the new approach. The advantages of method D are no residue, no redox reaction, insignificant loss of analytes and enhanced sensitivity (at ppb level vs ppm of the other methods). This approach should be considered especially when testing heavy metals and complex matrices. Its disadvantages are that it is more time consuming and requires the presence of an operator.

Humans↗
PubMed1998

[Determination of cyanide in whole blood by completely differential spectrophotometry].

This paper introduced a method for the determination of cyanide in whole blood by completely differential spectrophotometry with pyridine-pyrazolone method after stabilization by addition of silver sulfate and separation by distillation. The analytical results showed a precision 5.4% (n = 6) for the determination of 0.068 microgram.ml-1 CN- in whole blood. The average recovery was 97.4%. This method was successfully used for the determination of cyanide in whole blood of non-smokers and smokers.

Cyanides↗
PubMed1998

[A preliminary study of plasma oxidase activity by spectrophotometry on the healthy middle-aged and old volunteers in Changsha].

The plasma oxidase activities (POA) in 26 healthy volunteers were determined by spectrophotometry. The results showed that the POA value of the 26 cases was obviously lower (78.90 +/- 8.12 U.L-1) than that in Lasla's (84 +/- 5 U.L-1) (P < 0.05). A preliminary normal reference range of POA (45-60 years old) in Changsha was established. This method is an accurate (CV = 3.9%), cheaper, and easy one and applicable for clinical laboratories.

Age Factors↗
PubMed2000

Determination of tetrahydrozoline hydrochloride and fluorometholone in pharmaceutical formulations by HPLC and derivative UV spectrophotometry.

Two methods for the quantitative determination of tetrahydrozoline hydrochloride (1) and fluorometholone (2) in pharmaceutical eye drops (Efemoline) are described. The procedures are based on derivative UV spectrophotometry and HPLC. In the former method, d2A/d lambda 2 values were measured in methanol at 226 and 282 nm for 1 and 2, respectively. The relative standard deviations for the method were found to be 1.06% for 1 and 0.98% for 2. The latter method based on a reversed phase HPLC system using a Partisil 5 ODS analytical column. The mobile phase used for the separation of 1, 2 and internal standard (lidocaine) was methanol/acetonitrile/water (50:50:10 v/v) and the compounds in the eye drops were detected at 220 nm using an UV detector. The relative standard deviations for the HPLC method were determined to be 0.61% and 0.50% for 1 and 2, respectively. The proposed methods, which give thoroughly comparable data, are simple, rapid, and allow precise and accurate results and could be used for commercial formulations containing tetrahydrozoline hydrochloride and fluorometholone in combination.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Improved determination of mercury complex with Thiomicher's ketone by beta-correction spectrophotometry.

Determination of the mercury complex formed with Thiomicher's ketone (TMK) was improved by beta-correction spectrophotometry in the presence of a nonionic surfactant at pH 5. The complex formed was Hg(TMK)2, and its true molar absorptivity is reported for the first time: epsilon Hg(TMK)2(560) = 1.04 x 10(5) L/mol.cm. In addition, the stability constant of Hg(TMK)2 was equal to 3.64 x 10(10) at an ion strength of 0.01 at 20 degrees C. Results from analyses of wastewater samples showed that the relative standard deviations were < or = 8.3%, and the recoveries of mercury ranged from 90 to 110%.

Chelating Agents↗
PubMedDate not supplied

Application of infrared spectrophotometry to the identification of inorganic substances in dosage forms of Antacida group.

Powdered tablets from the Antacida group: Alusal, Milk of Magnesia, Alumag, Maalox, Magnosil, Alugastrin, Malugastrin, Rennie, and components deciding about their antiacidity like Al(OH)3, Mg(OH)2, Mg2Si3O8, NaAl(OH)2CO3, MgAl(OH)(SO4)2, CaCO3, MgCO3, were subjected to infrared spectrophotometric investigations. It was found that infrared spectra of each pharmaceutical compound are different and show a series of characteristic maxima, by which they can be identified with in the spectral range of 4000 cm-1-200 cm-1. Comparison of infrared spectra of finished products with spectra of their components it was showed that the application of infrared spectrophotometry methods enabled us to prove the presence of particular compounds used in formulations. Tablet mass and odorizing agents do not cause significant changes in spectra of the tablets studied, preparations from the Antacida group.

Antacids↗
PubMed2000

Second derivative ultraviolet spectrophotometry and HPTLC for the simultaneous determination of vitamin C and dipyrone.

Two accurate, precise and sensitive thin layer chromatographic (TLC) and second derivative UV-spectrophotometric procedures are described for the simultaneous determination of ascorbic acid and dipyrone in pure form and in pharmaceutical dosage forms. The TLC method involved direct application of methanolic solutions of tested samples on silica gel TLC plates using water:methanol (95:5 v/v) as developing system. The developed plates were then directly scanned at 260 nm using a TLC scanner. The second method depends on second derivative UV-spectrophotometry with zero crossing technique of measurement. Second derivative amplitudes at 280 and 272 nm were selected for the determination of ascorbic acid and dipyrone, respectively. Both methods show good linearity, precision and reproducibility. They are simple and do not require manipulation prior to analysis. The proposed methods have been successfully applied to the determination of the drugs in various pharmaceutical dosage forms such as tablets and ampoules.

Ascorbic Acid↗
PubMedDate not supplied

Determination of chelate complexes by spectrophotometry; L-ascorbic acid with cadmium (II) and zinc (II) in alkaline solution.

The chemical behaviour of L-ascorbic acid (H2Asc) with cadmium (II) and zinc (II) in alkaline medium was studied. The total stability constants of the examined complexes and their composition were determined by spectrophotometry (Jacymirsky and computer) method. An attempt has been made to explain the nature of complexes formed in the systems Cd (II)-H2Asc-H2O and Zn (II)-H2Asc-H2O and the interaction between these compounds.

Ascorbic Acid↗
PubMed1975

Effect of the matrix of the standard on results of atomic absorption spectrophotometry of zinc in serum.

Zinc in pooled human serum, diluted 10-fold with demineralized water, was determined by flame atomic absorption spectrophotometry. Recoveries of zinc added to the serum were calculated by use of standards prepared in water, physiological saline, synthetic serum, or dilute HNO3 (10 ml/liter). The flow rates were essentially the same (9.1 to 9.3 ml/min) for water, diluted synthetic serum or actual human serum, and diluted nitric acid. The mean apparent percentage recoveries (plus or minus SD) were the best (102.6 plus or minus 2.5) when the standards were prepared in nitric acid; the values obtained when standards in water were used were too high (111.5 plus or minus 3.9); those with standards prepared in physiological saline (92.0 plus or minus 3.2) or synthetic serum (92.3 plus or minus 2.5) were too low.

Evaluation Studies as Topic↗
PubMed1975

Direct determination of total serum cholesterol by use of double-wavelength spectrophotometry.

We describe a simple, accurate method for direct determination of total cholesterol in serum. Systematic investigation of a previously described modified Liebermann-Burchard reagent has indicated the necessity of accounting for both bilirubin interference and decreased specificity owing to exothermia. Double-wavelength spectrophotometry was used to optically null out bilirubin as an interfering factor, whereas adding serum to the cold reagent increases its specificity for the cholesterol color reaction. Comparison of 106 cholesterol values with those obtained by the procedure of Abell et al. [J. Biol. Chem. 195, 357 (1952)] yielded a correlation coefficient greater than 0.99; our inter-run coefficient of variation of polled laboratory serum was 1.7%.

Bilirubin↗
PubMed1997

[Determination of adenosine and thymidine in Fritillaria bulbs by ultraviolet spectrophotometry].

A convenient method for quantitative analysis of the nucleosides in Fritillaria bulbs has been developed by means of thin layer chromatography and ultraviolet spectrophotometry. The MeOH extracts from four species of Fritillaria were analyzed with this method. The results show that both adenosine and thymidine in the four species are quite disparate, suggesting that the nucleosides may be responsible for the anti-coagulative activity of Fritillaria.

Adenosine↗
PubMed2001

[Measurement of formaldehyde in disinfectant with spectrophotometry].

Formaldehyde in disinfectant was measured by acetylacetone spectrophotometry. The regression equation was linear when the formaldehyde concentration was smaller than 10 micrograms/ml. The detection limit was 0.08 microgram/ml. The accuracy was less than 3.9% and the recovery varied between 100.2%-108.2% for formaldehyde disinfectant with different concentration, which was similar to titrimetry. It was demonstrated that the method was simple, reproducible, sensitive, precise and accurate, making it important for assay of formaldehyde in disinfectant when disturbance caused titrimetry unavailable.

Disinfectants↗
PubMedDate not supplied

Column preconcentration of trace manganese with the ion pair of 2-nitroso-1-naphthol-4-sulfonic acid tetradecyldimethylbenzyl-ammonium chloride supported on naphthalene and determination by derivative spectrophotometry.

A column preconcentration method has been developed for the determination of trace amounts of manganese by preconcentration on 2-nitroso-1-naphthol-4-sulfonic acid (nitroso-S)-tetradecyldimethylbenzylammonium (TDBA) naphthalene as an adsorbent using a simple funnel tipped glass tube. Manganese reacts with nitroso-S to form a water soluble brown colored chelate anion. The chelate anion forms a water insoluble Mn-Nitroso-S-TDBA ion pair on naphthalene packed in a column in the pH range 9.6-10.5 at a flow rate of 1-2 ml/min. The solid mass consisting of manganese complex and naphthalene is dissolved in 5 ml of dimethylformamide (DMF) and the metal determined by second derivative spectrophotometry. The calibration curve is linear in the concentration range 0.25-35.0 micrograms of Mn in 5 ml of the final DMF solution. Eight replicate determinations of 25 micrograms of standard manganese solution give a mean peak height of 4.0 with a correlation coefficient of 0.9995 and relative standard deviation of +/- 1.1%. The sensitivity was calculated to be 0.502(d2 A/d lambda 2)/microgram ml-1 from the slope of the calibration curve. The detection limit was 0.020 microgram ml-1 for manganese at the minimum instrumental settings (signal to noise ratio = 2). Various parameters effecting the method such as the effect of pH, volume of aqueous phase and interference of a number of metal ions on the determination of manganese have been evaluated to optimize the conditions for its determination in standard alloys and biological samples.

Adsorption↗