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At least 523 records · Page 29Linked to original sources
PubMed1991

[Study on the multiwavelength coefficient spectrophotometry and its application].

This paper reveals a general principle of multiwave length spectrophotometry and puts forward a multiwave length coefficient method to determine mixed components system. The determination of the coefficients and the connection between the coefficients with the method are discussed in the paper. Using several groups of coefficients, according to the method, a mixed components of chlorpromazine hydrochloride and promazine hydrochloride were assayed at the same time. The laboratory results of recoveries indicates that the precision and the accuracy are good, and, different coefficients do not make a notable impact on the method.

Chlorpromazine↗
PubMed1990

[Simultaneous determination of brucine and strychnine in semen Strychni by dual wavelength spectrophotometry and studies on processing principles of semen Strychni].

The paper reports the experimental result of the simultaneous quantitative determination of strychnine (ST) and brucine(BR) in Semen Strychni by dual wavelength spectrophotometry. The result shows that there are some deviations in the official method, because the wavelength combination might not have been chosen rightly and the correct coefficient is inconsistent with the facts. We have made a study of the thermal stability of ST and BR, too. On this basis a baking principle for Semen strychni is spelt out.

Drugs, Chinese Herbal↗
PubMed1990

Evaluation of the depth sensitivity of tissue reflectance spectrophotometry in gingival measurement.

Tissue reflectance spectrophotometry (TRS) can estimate hemoglobin concentration (Hb index) and oxygen saturation of hemoglobin (apparent SO2) in tissues. Reflectance spectra were measured in a gingiva-model and in human gingival biopsies by TRS. The gingiva-model was composed of human red cells and white gel in a cuvette placed on a black or white surface. The distance from the bottom surface of the cuvette to the optical probe was decreased from 5.0 to 0.5 mm. The Hb index in the gingiva-model on the black surface was constant before decreasing at less than a 3.0 mm distance. However, the Hb index in the gingiva-model on the white surface showed a decrease at less than a 1.5 mm distance. Apparent SO2 was constant at more than a 1.0 mm distance. Reflectance spectra were measured from human gingival tissue preparations, by slicing them off with microtome and making them less thick each time. Changes in reflectance spectra were observed in less than 1.0-1.5 mm thick specimens. These results suggest that the sensitivity in TRS measurement may exist within 1.0-1.5 mm from the gingival surface, and the limit of depth at which the TRS can measure may be within 3.0 mm.

Gingiva↗
PubMedDate not supplied

Determination of biphenyl residues in citrus fruit by derivative infrared spectrophotometry.

A method for determination of biphenyl residues in whole citrus fruit is described. The mascerated fruit was distilled in an acid medium, the distillate was extracted with cyclohexane, and biphenyl was determined in the extract using various measures obtained by first and second derivative infrared (IR) spectrophotometry. Calculations were performed by PE680 and SNGLE programs on data obtained using a Perkin-Elmer Model 3600 data station. The relative precision of the determinations at 70 ppm was 1.8 to 2.0%; the detection limit was 5 ppm in all measurements, and recovery of spiking concentrations of 20 to 80 ppm ranged from 90.2 +/- 5.5% (for the amplitude of the 739 cm-1 peak of the first derivative) to 97.5 +/- 2.0% (for the trough-to-peak difference from the 737 cm-1 minimum to the 743 cm-1 maximum of the second derivative.

Biphenyl Compounds↗
PubMed1990

[Application of ridge regression spectrophotometry to the determination of multicomponents in aspirin compound tablet].

In this paper, a ridge regression method of spectrophotometry in multiwavelength is proposed. The basic principle and computing of this method applied to multicomponent analysis were discussed. This method was applied to simultaneous determination of multicomponents in aspirin compound tablet and satisfactory results were obtained. The experiment clearly indicates that ridge regression may provide a new approach to experimental measurement of multicomponent analysis computations.

Aspirin↗
PubMed1990

[Study on the determination of zinc in plasma after oral administration of licorzin by atomic absorption spectrophotometry and the pharmacokinetics of zinc in healthy volunteers].

A rapid, accurate and sensitive atomic absorption spectrophotometry was established for the determination of zinc in plasma after oral administration of licorzin to healthy volunteers. The plasma sample diluted with de-ionized water (1:1) was determined directly. A 5% glycerol solution was used as the solvent of zinc standard solution. The recovery of the proposed method was 97.3 +/- 4.3%. The precisions (CV%) of within-day and day-to-day were less than 5%. The pharmacokinetics of zinc in healthy volunteers after oral administration of 2.5 g licorzin was studied. The results showed that an one-compartment model (Ka = K) was found in 10 healthy volunteers. The pharmacokinetic parameters were as follows: Ka = K = 0.380h-1, Tmax = 2.7h, V = 33.03 L, T1/2 = 1.9h.

Adult↗
PubMedDate not supplied

Survey of total and bioavailable chromium in grain and cereal products by atomic absorption spectrophotometry.

The chromium content of samples of cereals, legumes, oil seeds, and alimentary pastes (in the latter, bioavailable chromium as well) was determined by atomic absorption spectrophotometry. The chromium content in whole cereals differs substantially and is mostly concentrated in pericarps. Variations occur not only among different types of cereals, but also among cereals of the same type, depending on the areas of origin. Concentration varies substantially even in samples of legumes and oil seeds. The content of bioavailable chromium (ethanol-extractable) is, in most cases, more than 50% of the total chromium amount. This makes these products particularly interesting as dietary supplements.

Amino Acids↗
PubMedDate not supplied

Analysis of illegally distributed anabolic steroid products by liquid chromatography with identity confirmation by mass spectrometry or infrared spectrophotometry.

Anabolic steroid products found in the illegal market are primarily oil-based injectables or tablets and often do not contain the ingredients declared on the label. An analytical scheme based on a reverse-phase liquid chromatographic (LC) system for screening, tentative identification, and quantitation is presented. Methanolic sample extracts are chromatographed on an octadecyl column using 2 mobile phases (methanol and (75 + 25) methanol-water) and tracked at 3 wavelengths (240, 210, and 280 nm) or with a photodiode array UV detector. Retention time ratios (RR) relative to testosterone and UV data are used for tentative identification. The same LC system serves as a cleanup and isolation step for identity confirmation by direct insertion probe mass spectrometry (MS) or Fourier transform infrared spectrophotometry (FTIR). Recoveries range from 96.2 to 100.2% for 11 different steroids extracted from sesame oil. LC RR values for over 40 steroids, analytical results for typical products, and MS and FTIR spectra for selected compounds are presented.

Anabolic Agents↗
PubMed1990

[Application of derivative spectrophotometry for determining plasma hemoglobin and semi-quantitative evaluation of urinary porphyrins].

We described a method using second-derivative spectrophotometry with a spectrophotometer Uvikon (Kontron) for the assay of plasma hemoglobin and urinary porphyrins. We evaluated the procedure for sensitivity, linearity, analytical recovery. Non specific interference is not significant and reproductibility is excellent. This simple, rapid, sensitive, not expansive method can be adapted for use in a clinical laboratory.

Humans↗
PubMed1975

Ultramicro analysis for copper, cadmium, and zinc in human liver tissue by use of atomic absorption spectrophotometry and the heated graphite tube atomizer.

We describe a method of analysis for copper, cadmium, and zinc in a 15-mg (wet weight) sample of human liver by atomic absorption spectrophotometry. The sample is digested with nitric acid (1.0 mol/liter), evaporated, and dilute HNO3 (10 mmol/liter) added. The reconstituted acid mixture is injected into the graphite tube atomizer for analysis of Cu and Cd and aspirated into the air--acetylene flame for measurement of Zn. The absorbance for each metal is suppressed with increasing pH. NaNO3, KNO3, KCl, and NaCl (e.g.) quench the Cd absorbance in acid solutions that contain no protein, but not in the presence of protein. Metal ions added to the predigestion human liver sample at 10 percent and 100 percent of the intrinsic metal concentrations were, respectively, 93 percent and 90 percent accounted for analytically in the case of Cu, 98 percent and 102 percent for Zn, and 101 percent and 93 percent for Cd. Analysis of a National Bureau of Standards' Bovine Liver Standard Reference Material yielded results corresponding to 99 percent (Cu), 112 percent (Zn), and 91 percent (Cd) of the mean expected concentrations of these metals. The between-run coefficient of variation for the bovine liver material was 6 percent for Cu, 9 percent for Zn, and 10 percent for Cd. For 16 histologically normal samples of human liver, the mean values were: Cu, 26; Zn, 293; and Cd, 6.0 nanograms of metal per milligram dry weight, in agreement with values published previously. The method can be easily and reliably applied to small samples of liver obtained by closed-needle biopsy.

Animals↗
PubMed1990

[Application of equal value derivative spectrophotometry to the determination of coptis alkali in wanshi niuhuang qingxin pills].

The total coptis alkaloids Wanshi Niuhang Qingxin Pills were determined by equal value derivative spectrophotometry in this paper. Quantitative analysis of six mixtures of medicinal herbs can be done easily on the extract. The average recovery of berberine.HCl is 98.55 +/- 1.90% (CV). The method features good reproducibility, favorable stability and high sensitivity.

Alkaloids↗
PubMed1990

[Simultaneous determination of 6 components contained in compound reserpine tablets by Kalman filtering spectrophotometry].

Kalman filtering spectrophotometry was investigated to assay the contents of vitamin B1, vitamin B6, chlordiazepoxide, dihydralazine sulfate, promethazine hydrochloride and hydrochlorothiazide in compound reserpine tablets consisting of 10 components. Absorption proportionality constant for each component was obtained by the application of non-negative least square method. The average recoveries for each were 97-103% with CV% less than or equal to 6.9 except vitamin B1 (n = 11).

Chlordiazepoxide↗
PubMedDate not supplied

Determination of total gossypol in cottonseed and cottonseed meals by derivative UV spectrophotometry.

A new method for the determination of total gossypol in cottonseed and cottonseed meals has been developed. The method involves oxalic acid hydrolysis of the bound gossypol in a methyl ethyl ketone-water azeotrope, partitioning the liberated gossypol into chloroform, and quantification by 2nd derivative UV spectrophotometry. The 2nd derivative transformation and measurement of the conventional analytical band around 300 nm permits direct quantification of all compounds containing naphthalene nuclei; chromogenic reaction is not required. The method was tested at concentration levels of total gossypol normally expected for cottonseed and cottonseed meal. Precision and accuracy data suggested an overall relative standard deviation of 4.0% and an overall recovery of 89.5%. Although results for cottonseed and solvent-extracted cottonseed meal analyses were comparable to those obtained by use of American Oil Chemists' Society methods, results were lower for screw-pressed meals. The lower results were attributed to the partial conversion of gossypol, during the cooking process of these meals, to compounds that differ in composition and structure from gossypol and which react with aniline to give false readings.

Aldehydes↗
PubMed1990

[The effect of the method of detecting indocyanine green (HPLC, spectrophotometry) on the determination of pharmacokinetic parameters].

The method of determination of indocyanine green (ICG) in plasma by means of high-performance liquid chromatography (HPLC) is compared with the method of spectrophotometry. A sample for HPLC is purified by deproteination with acetonitrile and the supernatant is directly spread on the column. The internal standard is diazepam. The mobile phase consists of 50% of phosphate buffer pH 6 prepared according to PhBs 4, 47% of acetonitrile and 3% of methanol. Detection takes place at 260 nm. Spectrophotometric analysis consists in the measurement of plasma absorbance at 805 nm. Correlation of both methods is linear r = 0.989, n = 20, p less than 0.05. From the curves of elimination of the dye from the blood bed the principal pharmacokinetic parameters were calculated by means of a one-compartmental model after single intravascular administration. In spectrophotometric examination, elimination of ICG seems to be slower as compared with HPLC.

Chromatography, High Pressure Liquid↗
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↗
PubMed1990

Determination of 2,6-dimethyl-4-(2'-nitrosophenyl)-3,5-pyridinedicarboxylic acid dimethylester in nifedipine by derivative UV-spectrophotometry in bulk material and pharmaceutical forms.

A method for the determination of 2,6-dimethyl-4-(2'-nitrosophenyl)-3,5-pyridinedicarboxylic acid dimethylester in nifedipine (bulk material and pharmaceutical formulations) by second-derivative ultraviolet spectrophotometry is described. The procedure is simple and rapid and gives accurate and precise results.

Dihydropyridines↗
PubMed1989

Qualitative and quantitative evaluation of chrysotile and crocidolite fibres with infrared spectrophotometry: application to asbestos-cement products.

Infrared (IR) spectrophotometry allows simple and rapid qualitative and quantitative evaluations of different types of asbestos, as well as of other inorganic particles. In particular, chrysotile and crocidolite have characteristic IR spectra, and optical density measurements in the 2710 nm band for chrysotile and the 12820 nm band for crocidolite permit the quantitative evaluation of each fibre either alone or in mixtures. IR spectra also provide information on changes in fibre structure and in chemical composition as the result, for example, of thermal treatment or acid leaching. The analytical method that we have developed can detect amounts as small as 0.1 mg of fibre in a 300-mg disk of potassium bromide using a low-cost IR spectrophotometer. The use of a Fourier transform IR spectrophotometer dramatically improves the sensitivity and selectivity. Computer-assisted analysis of spectra offers the possibility of reducing matrix interference and of comparing different spectra. The application of the IR technique to asbestos-cement products and insulating materials is described.

Asbestos↗