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 505 records · Page 28Linked to original sources
PubMed2005

[Spectrum analysis of erythrocyte intracellular hemoglobin with a novel fast multi-channel micro-spectrophotometry].

With the application of a novel fast multi-channel micro-spectrophotometry (MMSP), the absorption spectrum of intracellular hemoglobin molecule in a human single living red blood cell was monitored under the altered physiological environments (pH, temperature, partial pressure of oxygen, and osmotic pressure). It was found that on the absorption spectrum curve of hemoglobin the spike, the height and the position of the characteristic absorption peaks at 540 and 575 nm were altered obviously with the changes in physiological conditions, indicating that the concentration, structure and function of the hemoglobin in the red blood cell may be closely associated with the physiological environments.

Algorithms↗
PubMed2005

[The determination of chromium in feeds by flame atomic absorption spectrophotometry].

Chromium in feeds is regulated by China Standard GB 13078-2001. A method of flame atomic absorption spectrophotometry for the determination of Cr in feeds has been developed in allusion to shortage of China standard method. Several acetylene flow-rate, burner-high and the additive of interference suppressor NH4Cl were studied respectively on the effect of sensitivities of Cr(III) and Cr(VI). The two sets analytical average results of Cr in feed sample determined by calibration curves of Cr(III) and Cr(VI) were tested by t test, no marked discrepancy was found. Optimum instrumental conditions of Cr(III) and Cr(VI) with same sensitivity were confirmed. Sensitivity was 0.014 microg x mL(-1) with detection limit 0.70 mg x kg(-1). The recoveries were 94.4%-104.9%. Relative standard deviation of sample determination (5-6 times) was 1.90%-4.08%. This method is simply, fast and exact, the detection limit was answered for Cr limit in feeds regulated by GB 13078-2001, it can be applied to the analysis of Cr in feeds.

Acetylene↗
PubMed2005

[Multi-wavelength negative absorption fading spectrophotometry to determine trace nitrite and it's mechanism].

Using negative absorption rectifyingtechniquie, the authors investigated spectra of the reaction of nitrite with acridine yellow in 1.0 mol x dm(-3) (1 dm = 10 cm = 0.1 m) hydrochloric medium. The authors established the new dynamics method of mensuratiog trace nitrous acid radical by the negative absorption undertint spectrophotometry at multi-wavelengths, based on the linear relation between the negative absorbance value or the AT value of absorbance sum and the nitrous acid radical concetration in a certain range. The linear range was 7.2 x 10(-6) -3.6 x 10(-4) mol x dm(-3), RSD was 1.06%-3.12%, and CV (recovery) was 98.00%-100.20%. In application to the determination of nitrite in environmental water sample, satisfactory result was abtained with high accuracy, better selectivity and common ions ceasing to effect measuring. According to the change in the absorption peak value in the reactive system,the liquor acidity, the different order for added reagent, liquor temperature, reactive time, acid kind etc., the authors believe that the reaction of acridine yellow with mitrite is diazotization-coupling, under the condition of feasible pH value, temperature, and additive order of midium.

Hydrogen-Ion Concentration↗
PubMed2005

[Studies on the interaction between RNA with methyl violet and determination of RNA by spectrophotometry].

An analytical method for the determination of ribonucleic acid was established by spectrophotometry. At maximum absorption wavelength for methyl violet in the B-R buffer solution, and under the best conditions, the degree of decrease of the absorbance was linear with the amount of ribonucleic Acid. It was a new and preferable approach for the determination of ribonucleic Acids. The method with the linearity range was 1.0 to 8.0 microg x mL(-1) and the detection limit was 0.52 microg x mL(-1), and the correlation coeffient was 0.9999. This method was simple, rapid, and selective. So it was satisfactory to the application for the determination of ribonucleic Acid. The reaction mechanism was electrostatic interaction to make molecular association of RNA with methyl violet, to go on antiion permutation and bonded reaction of concert.

Gentian Violet↗
PubMed2005

[Study on extractive spectrophotometry for determination of amoxicillin with ionic associate].

A method of extractive spectrophotometry has been proposed for the determination of amoxicillin (AMO). The ion pairs complex of amoxicillin with methylene blue (MB) can be extracted into 1,2-dichloroethane at pH 3.3 and has absorption maximum at 657 nm. The ratio of amoxicillin to methylene blue in the ion pairs complex is 1:1. The apparent molar obsorptivity of ion pairs complex is 5.0 x 10(4) L x mol(-1) x cm(-1) at 657 nm. The calibration graph generated is linear over the range of 0.4-6.8 mg x L(-1) drug in solution with a correlation of 0.9989. The detection limit is 0.01 mg x L(-1) and the recovery of AMO is 97.5%-101.3%. The present method has been applied to the determination of amoxicillin in pharmaceutical formulations and urine samples with satisfactory results.

Amoxicillin↗
PubMedDate not supplied

New methods for determination of cinnarizine in mixture with piracetam by spectrodensitometry, spectrophotometry, and liquid chromatography.

Four new methods were developed and validated for the determination of cinnarizine HCl in its binary mixture with piracetam in pure and pharmaceutical preparations. The first one was a densitometric analysis that provides a simple and rapid method for the separation and quantification of cinnarizine HCI. The method depends on the quantitative densitometric evaluation of thin-layer chromatograms of cinnarizine HCI at 252 nm over concentration range of 1-6 microg/spot, with a mean accuracy of 100.05 +/- 0.91%. The second method was determination of the drug using a colorimetric method that utilizes the reaction of 3-methyl-benzothiazolin-2-one in the presence of FeCl3 as an oxidant. The green color of the resulting product was measured at 630 nm over concentration range 10-40 microg/mL, with a mean accuracy of 100.10 +/- 1.13%. The third method was a direct spectrophotometric determination of cinnarizine HCI at 252 nm over the concentration range 7-20 microg/mL, while piracetam was determined by derivative ratio spectrophotometry at 221.6 nm over concentration range 5-30 microg/mL, with a mean accuracy of 100.14 +/- 0.79 and 100.26 +/- 1.24% for cinnarizine HCI and piracetam, respectively. The last method was a liquid chromatography analysis of both cinnarizine HCI and piracetam, depending on quantitative evaluation of chromatograms of cinnarizine HCI and piracetam at 252 and 212 nm, respectively, over the concentration range 10-200 microg/mL for cinnarizine HCI and 20-500 microg/mL for piracetam, with a mean accuracy of 100.03 +/- 0.89 and 100.40 +/- 0.94% for cinnarizine HCI and piracetam, respectively. The proposed procedures were checked using laboratory-prepared mixtures and successfully applied for the analysis of their pharmaceutical preparations. The validity of the proposed procedures was further assessed by applying the standard addition technique. Recoveries were quantitative, and the results obtained agreed with those obtained by other reported methods.

Calcium Channel Blockers↗
PubMed2005

[Determination of catechin by three wavelength spectrophotometry and the antioxidation effect in natural teas and their beverages].

OBJECTIVE: To determine the catechin and the antioxidation effect in natural tea and their beverages. METHODS: Three wavelength spectrophotometry can eliminate the absorbance error of interfering components, turbid solution and the scattering effect. Background changedwith concentration changed and asymmetric absorption peak problems can be solved, and the antioxidation effect of natural tea and their beverages was studied by the flow-injection chemiluminescence. RESULTS: The recovery is 95.2%-102.0% and the coefficient of variation is 1.05%. Conclusion The results have shown that natural tea and their beverages are abundant in the catechin compounds and strong antioxidative effect.

Antioxidants↗
PubMedDate not supplied

Determination of amlodipine in pharmaceutical dosage forms by liquid chromatography and ultraviolet spectrophotometry.

A liquid chromatography (LC) method and an ultraviolet (UV) spectrophotometric method were developed and validated for quantitative determination of amlodipine in tablets and compounded capsules. The isocratic LC analyses were performed on an RP18 column using a mobile phase composed of 0.1% (v/v) ortho-phosphoric acid (pH 3.0) -acetonitrile (60 + 40, v/v) at a flow rate of 1.0 mL/min. The UV spectrophotometric method was performed at 238 nm. The analytical methods were validated according to International Conference on Harmonization Guidelines. The calibration graphs were linear [correlation coefficient (r) > 0.999] in the studied concentration range of 10-30 microg/mL for LC and 10-35 microg/mL for UV spectrophotometry. The relative standard deviation values for intraday and interday precision studies were less than 2%, and the accuracy was greater than 98% for both methods. The specificity of the LC method was proved using forced degradation. Statistical analyses showed no significant difference between the results obtained by the 2 methods. The proposed methods are precise and accurate and can be applied directly and easily to the oral pharmaceutical preparations of amlodipine.

Amlodipine↗
PubMed2006

[Determination of six metal elements in plant Bupleurum scorzoneri folium Willd. by flame atomic absorption spectrophotometry (FAAS)].

The objective in this paper was to determine the amount of metal elements in the Plant Bupleurum scorzoneri folium Willd. by flame atomic absorption spectrophotometry (FAAS). FAAS method was established for the determination of Ca, Mg, Fe, Cu, Zn and Pb in the Plant Bupleurum scorzoneri folium Willd. after digestion with HNO3-HClO4 (V : V= 4 : 1) at 90-95 degrees C and at normal pressure. In the meantime, the optimum parameters of FAAS and the effects of solution medium on the results were studied. The analytical results of Ca, Mg, Fe, Cu and Zn were 5,588.9, 1,790.5, 869.3, 78.4, 44.3 microg x g(-1) respectively, and Pb was not checked out in the samples. The results showed that the recovery of standard addition was 99.57%-102.10%, the relative standard deviation (n= 9) was 0.18%-2.26%. The method is quick, simple and convenient, and the results are satisfactory.

Bupleurum↗
PubMed2006

[Simultaneous determination of total flavone and total saponin in Gynostemma pentaphyllum by signal multiplier spectrophotometry].

Important chemical constituents analysis for the total flavone and total saponin in Gynostemma pentaphyllum is described. The colour reactions of flavones and saponines with vanillin-perchloric acid in acetic acid produced the good absorptions at 451 and 547 nm, but the absorption peaks too overlapped to be determined simultaneously. A new method for the total flavone and the total saponin in Gynostemma pentaphyllum to be determined by signal multiplier spectrophotometry simultaneously without any preliminary separation was proposed. For quantitative analysis, the rutinum as a standard of the total flavone and the ginsenoside Rb1 as standard of the total saponin were applied. The experiment results showed that the regression equations of concentration and deltaA were obtained: deltaAflavone = 0.0133+4.417 0Cflavone, relation coefficient rflavone = 0.9994, and the total flavone concentrations were in 0-0. 16 microg x mI(-1) with deltaA obeying linear relation; deltaAsaporin = 2.775 5Csaponin -0.8881 x 10(-2), relation coefficient rsaponin = 0.9991, and the total saponin concentrations were in 0-0.30 microg x mL(-1) with deltaA obeying linear relation respectively. The recovery ratio was 104.0%-113.0% and 86.8%-94.6% respectively. The RSDflavone was less than 0.58% (n = 9) and RSDsaponin was less than 0. 35% (n=9) respectively. The proposed method is simple, rapid accurate and feasible.

Feasibility Studies↗
PubMed2006

[Determination of thirteen metal elements in the plant Foeniculum vulgare Mill. by flame atomic absorption spectrophotometry].

The objective of the paper is to determine the amount of metal elements of Na, K, Mg, Ca, Cu, Zn, Mn, Fe, Co, Ni, Cd, Cr and Pb in the planted Foeniculum vulgare Mill. by flame atomic absorption spectrophotometry (FAAS), after the cinefaction and the digestion with HNO3-HClO4 (phi 4:1) at 90-95 degrees C and normal pressure. The optimum parameters of FAAS and the effects of solution medium on the results were investigated. The analytical results show that the amount of Na, K, Mg, Ca, Mn, Fe, Cu, Zn and Pb was 1508.7, 27653.0, 2036.0, 4848.1, 24.8, 323.5, 15.2, 23.7 and 10.8 microg x g(-1), respectively, and that of Co, Ni, Cd and Cr was not checked out in the samples. The recovery of standard addition is 97.45%-102.50%, the relative standard deviation (n=9) was 0.34%-2.77%. The characteristic method is quick, simple and convenient and the results are satisfactory.

Foeniculum↗
PubMed1991

[Determination of megestrol acetate and estradiol valerate in injection of microencapsulated compound megestrol acetate by secondary derivative spectrophotometry].

The paper reports the simultaneous determination of megestrol acetate and estradiol valerate in the injection of microencapsulated compound megestrol acetate by secondary derivative spectrophotometry. The experimental results showed that the average recoveries of the two drugs were 98.8% and 98.0%, respectively, and that the coefficients of variation were 0.71% and 1.81%, respectively.

Capsules↗
PubMed1991

[Application of differential derivative spectrophotometry to the determination of total chlorogenic acid in Lonicera japonica Thunb. and yinqiao jiedu pian].

The total chlorogenic acid in Lonicera japonica and yinqiao jiedu pian was determined by differential derivative spectrophotometry in this paper. Quantitative analysis of this component in eight mixtures of medicinal herbs can be done without any separation. The average recovery of total chlorogenic acid is 100.40 +/- 1.82% (CV). The method features good reproducibility, favorable stability and high sensitivity.

Chlorogenic Acid↗
PubMed1991

[Determination of the copper content in healthy placenta and placenta in gestosis using atomic absorption spectrophotometry].

Several complications in pregnancy seem to be related to the fluctuations of serum copper. In particular, values of serum copper over the normal range, have been associated to pregnancies complicated by EPH-gestosis. In this study we have evaluated the copper concentration in samples of placenta from 15 gravidas affected by EPH-gestosis and from 15 healthy gravidas with atom absorption spectrophotometry. The results of our study confirm the presence of an elevated copper concentration in the EPH-gestosis patients group (mean value: 196 micrograms/100 g of placental tissue). We can hypothesize that the result is due to a reduced copper uptake from the fetus.

Copper↗
PubMed1991

[Determination of chlorphenamine and propantheline bromide in pukeling tablets by differential--linear combination derivative spectrophotometry].

This paper provides the basic principle and experimental technique of differential--linear combination equal value derivative spectrophotometry. Quantitative analysis of three or four component--mixture can be done without separation. This method was investigated to assay the contents of chlorphenamine and propantheline bromide in Pukeling tablets by using UV-210A spectrophotometer. The average recoveries of chlorphenamine and propantheline bromide were 100.2 +/- 1.49% (CV) and 99.89 +/- 1.03% (CV) respectively. The results showed that it not only can effectively remove disturbances from each other, but also give higher sensitivity and accuracy.

Chlorpheniramine↗
PubMed1991

[Determination of aluminum in serum using electrothermal atomic absorption spectrophotometry].

A simple and sensitive method for the determination of aluminium in human serum by electrothermal atomic absorption spectrophotometry has been developed. In view of contradictory data in literature all relevant analytical conditions have been tested. The method involves simple dilution with a 0.05% solution of Triton X-100 and atomization on the wall of a pyrolytically coated graphite tube. The sensitivity of the method is about 1 microgram/L and precision less than 11%. The method of standard addition is recommended for calibration, but the use of a calibration curve based on serum with a low content of aluminium is also possible.

Aluminum↗
PubMed1991

[Study on polymorphism of gossypol by infrared spectrophotometry and X-ray diffraction].

The polymorphism of gossypol has been investigated by IR spectrophotometry and X-ray diffraction. Nine samples of gossypol crystallized from mixed solvent of ether, ethanol and water (1:2:2), five samples from chloroform and ten samples from petroleum ether (bp 60-90 degrees C) were determined. Significant differences in the infrared spectra of gossypol crystallized from three solvents were observed near 3500 cm-1. The spectrum of gossypol crystallized from mixed solvent of ether, ethanol and water (mp 183-184 degrees C) showed bands at 3500 (sh), 3470, 3375 cm-1; that from chloroform (mp 198-199 degrees C) at 3455, 3415 (sh) cm-1 and that from petroleum ether (mp 213-214 degrees C) at 3510, 3495, 3430 (sh), 3410 cm-1. Moreover, the spectra of the three forms of gossypol showed slightly different bands at 780 and 600-400 cm-1. Gossypol crystallized from the three solvents showed the same infrared spectra after being crystallized from acetone. Significant differences in the X-ray diffraction pattern of gossypol crystallized from the three solvents were also observed. Angles, intensities and D-values of most of the X-ray diffraction peaks were listed.

Crystallization↗