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At least 487 records · Page 27Linked to original sources
PubMed1998

[Study on the determination of tung oil adulterated in vegetable oils by first derivative spectrophotometry].

A method of first derivative spectrophotometry for qualitative and quantitative analysis of tung oil adulterated in vegetable oils, including peanut oil, bean oil, rape seed oil, tea seed oil, palm oil and mixed vegetable oil, was established. The spectrum of tung oil features three valleys at 291.3, 278.3 and 266.4nm, and three peaks at 284.1, 271.5 and 260.7nm. At 291.3nm, the coefficient (deltaE(1%)1cm/deltalambda) was -1.03 x 10(3). When the concentration of tung oil adulterated in vegetable oils was downed to 0.1%, the above specialities still remain and the changes in wavelengths were not more than 0.7nm. The detection limit of the concentration of tung oil adulterated in vegetable oils was lower than 0.1%.

Food Analysis↗
PubMed1997

[Determination of Keganmin tablet with multi-wavelength K-factor spectrophotometry].

The contents of phenacetin, aminopyrine and caffeine in Keganmin tablet were determined simultaneonsly with multiwavelength K -factor spectrophotometry. The result is accurate and the method is rapid. The average recoveries and relative standard deviations of the analysis for phenacetin, aminopyrine and caffeine were 99.91%, 0.41%; 100.1%, 0.29%; 100.1%, 0.56%, respectively.

Aminopyrine↗
PubMed1999

[Determination of 2,4-dinitrochlorobenzene in environmental water by primary-secondary wavelengths new spectrophotometry].

In basic solution, dinitrochlorobenzene may react on pyridine to form a purplish red compound. In this paper with the absorption property of a suspended liquid against light a new analytical method as primary-secondary wavelengths spectrophotometry was studied to determine trace dinitrochlorobenzene in environmental water. In 0-50 microg dinitrochlorobenzene/25 mL, the calculation curve is very stable and hardly affected by environment conditions. Experiments for practical waters have shown that the detection limit was 0.7 microg/25 mL dinitrochlorobenzene and RSD < or = 2.7% and the recovery rate was 99.2%-101.0%.

Dinitrochlorobenzene↗
PubMed1999

[Research into determination of tricomponent sample by ridge regression spectrophotometry].

In this paper ridge regression spectrophotometry was used to analyze three components--Acetaminophen, P-Ni-trophenol and P-Aminophenol with absolute ethanol as the solvent. The basic principle and analytical steps of the method were described in detail. The experimental results show that the recovery of each component ranges from 99.24% to 101.31% with the medium of absolute ethanol. As compared with conventional methods, this method is simple, rapid and suitable for computer-aid analysis.

Acetaminophen↗
PubMed1999

[Continuous determination of Zn, Cu and Mn in tea by flame atomic absorption spectrophotometry].

This paper reports the determination of trace metals Zn, Cu and Mn in tea by flame atomic absorption spectrophotometry. The method is simple and rapid with good precision and accuracy. The characteristic concentration is 0.009 microg/mL/1% for Zn, 0.031 microg/mL/1% for Cu and 0.017 microg/mL/1% for Mn, respectively. The relative standard deviation is between 0.9% and 5.0%. The recovery rate is between 92.0% and 106.0%.

Camellia sinensis↗
PubMed1999

[Determination of copper in waste water by beta-correction new spectrophotometry].

In pH 5-6 solution copper [Cu(II)] can react on p-dimethylaminobenzylidene rodamine (PDR) to form red compound. Beta-correction spectrophotometry was studied to determine trace copper. It can remove the absorption interference of surplus PDR in reaction solution to raise the analytical sensitivity. Experiments for samples showed that RSD = 2.9% and the recovery rate was 87.7%-112%. The minimium concentration of the determination is 0.55 microg/25 mL. The method is suited to analyse copper in metals and waste water.

Copper↗
PubMed1999

[Determination of the content of aminopyrine in antongding injection by orthogonal function spectrophotometry].

Determination of the content of aminopyrine in the antongding injection by orthogonal function spectrophotometry was reported in this paper. The six wavelengths for the determination are 257, 261, 265, 269, 273 and 277 nm. The concentration of aminopyrine in the range of 5-25 microg x mL(-1) is in a good linear relation to P2, and the regression equation is P2 = + 0.018 - 0.032 9c, r = 0.999 9. The average recovery and relative standard deviation are 100.3% and 0.40%, respectively. On the basis of the data observed it is concluded that this method shows no obvious difference as compared with Hebei province pharmacy regulation.

Aminopyrine↗
PubMed1998

[Indirect determination of trace amount of oxalic acid radical by the I2-CCl4 extraction spectrophotometry].

The article studies that in dilute H2SO4 dielectric substance IO3(-) reacts with C2O4(2-) to release certain amount of iodine under certain reaction condition: 2IO3(-) + 5C2O4(2-) + 12H+ = I2 + 10CO2 increasing + 6H2O therefore the method of indirect determination with I2-CCl4 extraction spectrophotometry is established. The reaction temperature is controlled in 90 degrees C; the reaction time 3 minutes; the reaction acidity pH1.0-2.0. The common ion basically does not affect the determination. The lowest detection limit of C2O4(2-) is 0.08 microg x mL(-1). After comparing the method of the recovery experiment with that of other determination, a satisfactory result is aquired and the recovery is between 96-98%.

Calibration↗
PubMed1998

[Determination of trace Fe in doxycycline hydrochloric acid by flame atomic absorption spectrophotometry].

This paper reports the development of the determination of trace metal Fe in doxycycline hydrochloric acid by flame atomic absorption spectrophotometry. The method is convenient to determine elements in doxycycline hydrochloric acid. The results show that the method offers good precision and accuracy. The relative standard deviation for Fe was 0.54% and the rate of recovery was 99.2%.

Calibration↗
PubMed1998

[Simultaneous determination of metronidazolum and vitamin B6 by the derivative spectrophotometry].

A new method for simultaneous determination of metronidazolum and vitamin B6 was established by the third derivative spectrophotometry in 0.1 mol/L HCl solution. The detection limits were 0.81 microg/mL for metronidazolum and 0.16 microg/mL for vitamin B6. The linear range of determination was 1.6-22.4 microg/mL for both metronidazolum and vitamin B6. This method has been applied to the determination of metronidazolum and vitamin B6 in tabellae metronidazoli compositae with satisfactory results. The coefficients of variation are below 2.26 and 2.65% and the recoveries are 93-102% and 99-101% for metronidazolum and vitamin 6, respectively.

Limit of Detection↗
PubMed2005

[Assay of three kinds of aluminum fractions (Al(a), Al(b) and Al(c)) in polynuclear aluminum solutions by Al-Ferron timed spectrophotometry and demarcation of their time limits].

Al-Ferron timed spectrophotometry assay is a basic method in the study on the formation of polynuclear hydroxyl aluminum species and their transformation laws in aqueous systems. In actual working process, this methodology has some dogmatism and arbitrariness in the time limits demarcation of the three kinds of aluminum fractions (Al(a), Al(b) and Al(c)) in polynuclear aluminum solutions, which makes this kind of classification rougher, and the experimental results non-reproducible. The reason for this difference is that the specific species within Al(a), Al(b) and Al(c) have different reaction mechanism and dynamics, and that specific species of Al(b) having different OH/Al ratios have different reaction rates with ferron. In this paper, the ExpAssoc distribution was applied to quantitatively fit the Al-Ferron reaction dynamics curve, and the extrapolation method was used to survey the 1 min measured value [Al(a)] of monomeric Al, which is hard to obtain in manual manipulation. The time demarcation between Al(b) and Al(c) should reach the point of the experimental data curve up to horizontal platform. The microwave-radiated technology was used to fast assay the total aluminum concentration [Al(T)]. With these methods, the contents of monomeric Al(a), polynuclear Al(b) and gel Al(c) can be conveniently and quantitatively measured. It offers a novel method for surmounting the arbitrariness in the measurement of the three kinds of aluminum fractions and the repetitive calculation of Al(a) and Al(b).

Aluminum↗
PubMed2005

Determination of arsenic in air particulates and diesel exhaust particulates by spectrophotometry.

A method was developed for the determination of trace arsenic by spectrophotometry. The proposed method is rapid, simple, and inexpensive. This method can be used for sensitive determination of trace arsenic in environmental samples and especially in air particulates. The results obtained by this method as a proposed method were compared with those obtained by hydride generation atomic absorption spectrometry as a popular reported method for the determination of arsenic and an excellent agreement was found between them. The method was also used for determination of arsenic associated with airborne particulate matter and diesel exhaust particulates. The results showed that considerable amount of arsenic are associated with diesel engine particulates. The variation in concentration of arsenic was also investigated. The atmospheric concentration of arsenic was different in different sampling stations was dependent to the traffic density.

Air Pollutants↗
PubMed2004

Characterization of free aromatic amino acids and estimation of exposition rate of phenylalanine in casein hydrolysates by second derivative spectrophotometry.

In this work, the second derivative spectrophotometry (SDS), a fast, simple and relatively low-cost method,-was used to characterize aromatic amino acids at two pH values (7 and 13) and to evaluate the exposition rate of Phe in casein hydrolysates prepared with papain. The results indicate that at 37 degrees C, pH 7.5 and an enzyme:substrate ratio of 4:100, for hydrolyzing casein by papain, the highest Phe exposition was observed. Therefore these are the most appropriate conditions for Phe removal and preparation of supplements for phenylketonurics. The use of SDS at pH 13.0 gives a good resolution of Tyr and Trp peaks. A similarity among SDS spectra of aromatic amino acids and protein hydrolysates, was also observed.

Caseins↗
PubMed2005

[Value of infrared spectrophotometry morpho-constitutional analysis of double J stent encrustations for indirect determination of urinary stone composition].

INTRODUCTION: A single stone analysis is necessary during the patient's clinical history in order to institute specific drug treatment and health and dietary measures to prevent stone recurrence. In practice, only one in every two stones is recovered for morpho-constitutional analysis. The objective of this study was to determine the place of double J stent encrustation analysis for indirect determination of stone composition. MATERIAL AND METHODS: Double J stents and stones from all patients treated in the same centre over 24 months were consecutively analysed by infrared spectrophotometry. The correlation coefficient 1, evaluating the concordance between the composition of stones and double J stent encrustation was estimated statistically by SPSS 12.0 software (0<1<1; 1=0: no concordance; 1=1: perfect concordance). RESULTS: 45 males and 27 females with a mean age of 45.3 years (range: 29-70) were included Double J stents were placed for: febrile obstruction (N=52; 72%), acute renal colic (N=15; 21%) and impaired renal function (N=5; 7%). Calculated values for 1 were: 0.78 for the concordance between the predominant constituent of the stone and the encrustation (N=72; p < 0.0005); 0.91 for the concordance between the nature of the encrustation of the upper loop and that of the lower loop of the stent (N=30, p < 0.0005). CONCLUSION: The composition of mineral encrustation of double J stents is a good marker of stone formation. This constitutes an alternative method that can be used by urologists when no stone is available for spectrophotometric analysis.

Adult↗
PubMed2005

[Determination of Chinese traditional medicine activity eliminating superoxide anion radical by kinetics spectrophotometry].

A new method to determine Chinese traditional medicine activity eliminating superoxide anion radical by kinetic spectrophotometry was developed. It is shown that the optimum determination condition may be obtained when wavelength is 520 nm, the concentration of enzyme is 4 x 10(-3) microg x mL(-1), the reaction time is between 2-7 min. Vitamin C activity eliminating superoxide anion radical was determined under the condition, and the results were identical with literature. The method is used to determine IC50 of Cortex Magnoliae Officinalis and Cortex Eucommia, and they are 7.580 and 323.800 mg x L(-1) respectively.

Antioxidants↗
PubMedDate not supplied

Estimation of pioglitazone hydrochloride and metformin hydrochloride in tablets by derivative spectrophotometry and liquid chromatographic methods.

Two simple and accurate methods of analysis to determine pioglitazone hydrochloride (PIO) and mefformin hydrochloride (MET) in combined dosage forms were developed using second-derivative spectrophotometry and reversed-phase liquid chromatography (LC). PIO and MET in combined preparations (tablets) were quantified using the second-derivative responses at 227.55 nm for PIO and 257.25 nm for MET in spectra of their solutions in a mixture of methanol and acetonitrile (30 + 70). The calibration curves were linear [correlation coefficient (r) = 0.9984 for PIO and 0.9986 for MET] in the concentration range of 8-40 microg/mL for PIO and 4-12 microg/mL for MET. In the LC method, analysis was performed on a Hypersil ODS-C18 column with 5 microm particle size using the mobile phase acetonitrile-water-acetic acid (75 + 25 + 0.3), adjusted to pH 5.5 with liquor ammonia, at a flow rate of 0.5 mL/min. Measurement was made at a wavelength of 230 nm. Both the drugs were well resolved on the stationary phase, and the retention times were 8.5 min for PIO and 16.0 min for MET. The calibration curves were linear (r = 0.9933 for PIO and 0.9958 for MET) in the concentration range of 4-20 microg/mL for PIO and MET. Both methods were validated, and the results were compared statistically. They were found to be accurate, precise, and specific. The methods were successfully applied to the estimation of PIO and MET in combined tablet formulations.

Acetonitriles↗
PubMedDate not supplied

Simultaneous determination of N-butylscopolamine and oxazepam in pharmaceutical formulations by first-order digital derivative spectrophotometry.

A simple method has been developed for the simultaneous determination of N-butylscopolamine bromide and oxazepam in pharmaceutical formulations using first-order digital derivative spectrophotometry. Acetonitrile was selected as the solvent in which both compounds showed well-defined bands. Both analytes showed good stability in this solvent when solutions of the analytes were exposed to light and temperatures between 20 degrees and 80 degrees C. The simultaneous determination of both drugs was performed by the zero-crossing method at 226.0 and 257.0 nm for N-butylscopolamine and oxazepam, respectively. The linear range of determination was found to be 2.5 x 10(-7) to 8.0 x 10(-5) mol/L for N-butylscopolamine and 7.1 x 10(-8) to 8.0 x 10(-5) mol/L for oxazepam. A very good level of repeatability (relative standard deviation) of 0.2% was observed for N-butylscopolamine and oxazepam. The ingredients commonly found in pharmaceutical formulations do not interfere. The proposed method was applied to the determination of these drugs in pharmaceutical formulations (capsules).

Acetonitriles↗