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PubMed2005

[Use of dinitrophenols in ion-pair extraction spectrophotometry of cationic tensides].

The application of 2,4-dinitrophenol and 2,6-dinitrophenol as reagents for a ion pair extraction spectrophotometry was tested. The ion pair extraction spectrophotometry experiments were carried out using a simplified procedure (test tube method). Four cationic tensides were used as model analytes. After the optimal conditions of the assay were being determined, the influence of the concentration excess of the reagents on the absorbance of the chloroform extract was investigated. Calibration curves were constructed; an estimation of limits of quantitation was performed and apparent molar absorption coefficients were determined. The obtained results show that both investigated dinitrophenols are suitable for the studied purpose.

Dinitrophenols↗
PubMed2005

[Ratio spectrophotometry and its application to assay of compound pharmacy preparations].

The present paper is to study ratio spectrophotometry for its application to the assay of compound pharmacy preparations. According to the feature of ratio spectra, the wavelength pair was selected at the peak point or valley point of ratio spectra to establish ratio spectrophotometry for the determination of Co-Chlorzoxazone tablet and injection of caffeine and sodium benzoate. The average recoveries and relative standard deviations for Chlorzoxazone and paracetamol were 100.0% and 1.28%, and 100.0% and 0.84%, respectively; the average recoveries and relative standard deviations for caffeine and sodium benzoate were 99.98% and 0.70%, and 99.91% and 0.78%, respectively. It is concluded that as long as the ratio spectra exhibit at least one peak and one valley, the results are satisfactory.

Acetaminophen↗
PubMedDate not supplied

Applications of derivative UV spectrophotometry for the determinations of fenbufen and ketoprofen in pharmaceutical preparations.

A methods for the determination of fenbufen and ketoprofen in pharmaceuticals by classical spectrophotometry--zero order derivative, first and second order derivatives spectrophotometry is described. using "peak-peak" (P-P) and, "peak-zero" (P-O) measurements. The calibration curves are linear within the concentration range of 2.0 - 12.0 microg x mL(-1) for fenbufen and ketoprofen. The procedure is simple, rapid and the results are reliable.

Ketoprofen↗
PubMedDate not supplied

Determination of citalopram in tablets by capillary zone electrophoresis and by direct and derivative UV-spectrophotometry.

Three rapid, simple and accurate analytical methods for the determination of citalopram in tablets were developed. The capillary zone electrophoresis (CZE) method was carried out using fused silica capillary with 67 mM phosphate buffer pH 7.0 as the background electrolyte, 30 kV of separation voltage and UV detection at 239 nm. The direct spectrophotometric method was performed by measuring the absorbance at the wavelength of 239 nm and derivative spectrophotometric assay was carried out by measuring the value of the second derivative of the spectrum at 210 nm. The linearity range for CZE method was 5-50 microg/mL and for both spectrophotometric methods was 2-12 microg/mL. The recovery in CZE was between 98.6 and 102.4%, in the direct spectrophotometry between 95.0 and 98.0% and in derivative spectrophotometry between 97.6 and 103.3%. The RSD values were between 1.36 and 2.30%, 1.80 and 2.70%, 1.52 and 2.68%, respectively.

Antidepressive Agents↗
PubMedDate not supplied

First-derivative spectrophotometry in the analysis of rosiglitazone in coated tablets.

First-derivative spectrophotometry, applying the peak-zero method, was developed for the determination of rosiglitazone (RSG) in coated tablets. The solutions of standard and sample were prepared in ethanol. Quantitative determination of the drug was performed at 331.4 nm (N = 4; delta lambda = 3.2 nm) and was evaluated for the parameters specificity, linearity, precision, and accuracy. The specificity test showed that there was no interference from excipients commonly found in the commercial pharmaceutical formulation at 331.4 nm. The standard curve showed a correlation coefficient of 0.9997. Precision was demonstrated by a relative standard deviation value of 0.50%. The recovery test resulted in an average of 100.06%, which confirmed the accuracy of the method. The results for first-derivative spectrophotometry (D(1)), liquid chromatography, and micellar electrokinetic chromatography were compared by analysis of variance (ANOVA), and there were no significant differences among these methods. Therefore, D(1) can be easily and directly applied to analyze RSG in coated tablets.

Chromatography, Liquid↗
PubMed2006

Comparative determination of halofantrine tablets by titrimetry, spectrophotometry and liquid chromatography.

Comparative determination of halofantrine tablets by titrimetry, ultraviolet spectrophotometry and liquid chromatography (LC) is described. Non-aqueous titrimetry on halofantrine hydrochloride tablets was carried out using glacial acetic acid as solvent, perchloric acid as titrant and crystal violet as indicator. Simultaneous potentiometric monitoring of end point delineated an exact color shade of indicator at the end point. Direct measurement of methanol solution, at 254 nm, was adopted for UV spectrophotometric method while reversed-phase liquid chromatographic (LC) method employed a C8 column (4.6 mm x 25 cm) with mobile phase consisting of methanol / 0.05 M NaH2PO4 (76:24, v/v) containing 55 mmol/L perchloric acid (pH 3.4) at a flow rate of 1 ml / min. The three methods gave precise and accurate results. Mean percentage recovery were obtained respectively as 100.73 +/- 0.41, 100.36 +/- 0.79 and 99.93 +/- 3.74% while coefficient of variation were 0.41, 1.36 and 3.74% for non-aqueous. UV spectrophotometry and LC. The three methods were successfully applied to analysis of halofantrine tablets (Halfan) and showed no statistically significant difference in accuracy (P > 0.05, ANOVA). Validated assay methods for halofantrine tablets have been developed. The titrimetric and spectrophotometric methods are of equivalent accuracy with the liquid chromatographic method and could be used for routine quality control of halofantrine tablets where LC method is not readily available.

Antimalarials↗
PubMed1991

[Use of infrared spectrophotometry of bile for diagnosis of cholelithiasis and predicting the chemical composition of the concrements].

Infrared spectrophotometry was applied in bile investigation from 47 cholelithiasis, 53 acalculous chronic cholecystitis and 23 control subjects. A cholelithiasis--specific shift in the absorption band appeared in the range of 900-1150 cm-1. Bile calculi removed at surgery from 110 relevant patients and bile from them were exposed to infrared spectrophotometry. The authors derived a correlation between the shape of the absorption band for bile in the range of 1500-1800 cm-1 and chemical composition of the concrement.

Bile↗
PubMed1991

[Update of a selected technique for uric acid determination in plasma and serum. Experimental study and value of derivative spectrophotometry].

A critical study of the candidate reference method for evaluation of uric acid in plasma proposed by the American Association of Clinical Chemistry is followed by testing in six laboratories. The dispersion of results is wide (CV greater than 5%). The importance of turbidity remaining after the deproteinization by trichloracetic acid is clearly demonstrated. This turbidity is really not reproducible from an operation to another one on the same serum. It is very likely responsible of the great dispersion of the results. After that, other deproteinization methods are tried. Ultrafiltration and ultracentrifugation give both defect errors because uric acid is in part bound to proteins. So it is necessary to find another technic which cancels the effects of turbidity on the absorbance readings in the ultra-violet domain. Experimental studies showed that uric acid may be evaluated with a good accuracy by derivative spectrophotometry, in lipid solutions as well as in cloudy ones. Turbidity was created by intralipid suspension additions. Various parameters hitting the method were examined (linearity, smoothing window...), taking as criterion the measure of overloaded serums at different levels. At last, the method is successfully transferred in several sites. In the case of blood serum, the respective influences of derivation and of repetition of final centrifugations are studied in order to estimate the effect of remaining turbidity. By the use of derivative spectrophotometry the improvement of the method of evaluation of uric acid proposed by A.A.C.C. is very noticeable; it reduces the variation coefficient between sites to less than 2%.

Animals↗
PubMed1989

[Simultaneous determination of four components in vitamin B compound tablets by Kalman filtering spectrophotometry].

The four principal components, vitamin B1, B2, B6 and nicotinamide in vitamin B compound tablet show certain instabilities individually and the amounts of these components differ considerably in the tablets, so their simultaneous determination without prior separation is usually difficult. This paper deals with the feasibility of using Kalman filtering spectrophotometry to do so, and makes some efforts concerning the deviation from the Beer-Lambert law due to mutual effects among the acting molecules. The results obtained were comparatively satisfactory both in precision and in accuracy. The average recovery of vitamin B1, B2, B6, and nicotinamide were 100.2 +/- 0.90% (CV), 100.3 +/- 1.7% (CV), 101.1 +/- 3.3% (CV), 99.90 +/- 0.65% (CV) respectively and were better than those in previous reports. All these show that the use of Kalman filtering spectrophotometry to the assay of vitamin B compound tablets is feasible.

Niacinamide↗
PubMed1989

[Simultaneous determination of aspirin and phenobarbital in infantile co-phenobarbital powder by dual wavelength K-ratio spectrophotometry].

Aspirin (I) and phenobarbital (II) in infantile co-phenobarbital powder were determined simultaneously using dual wavelength K-ratio spectrophotometry. I and II were analyzed with dual wavelength K-ratio spectrophotometry at 255, 244 and 236 nm. This method showed a mean recovery of 101.3% and a coefficient of variation of 1.6% for (I). The mean recovery and CV of II were 99.21% and 1.90% (n = 6) respectively. The method is simple, rapid and accurate.

Aspirin↗
PubMedDate not supplied

Comparison of four methods for digesting food samples for determination of trace levels of cadmium by flameless atomic absorption spectrophotometry.

We compared 4 digestion procedures, namely, sulfuric-nitric acid in an open flask, nitric acid under pressure, sulfuric-nitric acid with refluxing, and nitric-hydrochloric-peroxide with refluxing, for the determination of cadmium by flameless atomic absorption spectrophotometry in 3 foodstuffs: rice, beef, and cream cheese. The foodstuffs were homogenized and divided into several batches for analysis. The results were evaluated using a 2-way cross analysis of variance. The study revealed that the digestion procedure was a highly significant factor (P less than 10(-4] in the analysis of the 3 foods; whereas the nature of the foodstuffs was not significant for rice and meat and only slightly significant (P less than 10(-2] for cream cheese. When the foodstuffs were spiked with a known amount of cadmium, we observed a loss of the metal when the sulfuric-nitric acid procedure in an open flask and the nitric-hydrochloric-peroxide digestion procedure were used. Taken together, the results of the present study indicate that the choice of the reagents used for digestion of foodstuffs is a crucial factor for cadmium determination by flameless atomic absorption spectrophotometry.

Animals↗
PubMed1978

Comparative determination of phenytoin by spectrophotometry, gas chromatography, liquid chromatography, enzyme immunoassay, and radioimmunoassay.

Sera from patients being treated with phenytoin were analyzed for the drug by spectrophotometry, gas chromatography, radioimmunoassay, enzyme immunoassay, and liquid chromatography. The essay values obtained were intercompared statistically. Enzyme immunoassay and liquid chromatography appear to be attractive alternatives to the more traditional methods of spectrophotometry and gas chromatography. Our radioimmunoassay data correlated poorly with results by the four other methods.

Chromatography, Gas↗
PubMed1983

Hepatic hemodynamics in patients with chronic hepatitis or cirrhosis as assessed by organ-reflectance spectrophotometry.

Hepatic hemodynamics in patients with chronic liver disease has been studied by reflectance spectrophotometry of the liver in situ during peritoneoscopy. An organ-reflectance spectrophotometer used in this study was equipped with a branched optic fiber bundle, which coupled the liver surface with the spectrophotometer. The spectrophotometry could measure qualitatively and quantitatively the absorption of hemoglobin in the liver in situ, thus estimating the regional hepatic tissue blood hemoglobin concentration and the saturation level of hemoglobin in the regional tissue blood. The analysis of 42 cases has shown that the estimated regional hepatic tissue blood hemoglobin concentration and saturation level of hemoglobin decreased in most cirrhotic livers, suggesting that even in cirrhotic livers the hepatic oxygen extraction increased, concomitant with a decrease in the regional hepatic tissue blood hemoglobin concentration. The hepatic blood hemoglobin concentration estimated on the surface layer of the liver was positively correlated with the regional hepatic blood flow measured by radioisotope clearance technique. The estimated hepatic blood hemoglobin concentration was also correlated positively with serum albumin level and prothrombin time, and negatively correlated with plasma retention of indocyanine green at 15 min. It is concluded that the hepatic tissue blood hemoglobin concentration decreases significantly with progress of chronic hepatitis to cirrhosis. This decrease in hepatic blood hemoglobin concentration and flow is concomitant with a decrease in metabolic functions, which is not compensated by an increased hepatic oxygen extraction.

Adult↗
PubMed1978

Leak in evaporated milk by anodic stripping voltammetry and atomic absorption spectrophotometry: cooperative interlaboratory study.

The results of a cooperative study on the determination of lead in evaporated milk, using a double blind referee technique, are reported. This study was designed to determine the normal variability of methods currently used for lead analysis by canned food industry laboratories. Twenty-three laboratories participated in this study. Each laboratory was instructed to use atomic absorption spectrophotometry (AOAC 25.065), anodic stripping voltammetry, or carbon rod atomic absorption spectrophotometry. Overall, the results appear to be in close agreement with the spiking levels. The coefficient of variation for all laboratories was 36.0% at the 0.15 ppm lead level and 16.8% at the 0.40 ppm lead level.

Animals↗
PubMed1982

Zinc in plasma, neutrophils, lymphocytes, and erythrocytes as determined by flameless atomic absorption spectrophotometry.

Zinc is determined in neutrophils and lymphocytes (isolated from whole blood on discontinuous gradients of Ficoll-Hypaque) and in microliter quantities of plasma and erythrocytes by flameless atomic absorption spectrophotometry with greater sensitivity than with conventional flame atomic absorption spectrophotometry. Before analysis, neutrophils and lymphocytes are digested with nitric acid and diluted with de-ionized water. Plasma and erythrocytes required no digestion, only dilution. Overall CVs were 4.0, 3.0, 5.0, and 4.6% for neutrophils, lymphocytes, erythrocytes, and plasma, respectively. Matrix effects were fully compensated for by use of standard solutions that simulated the sample matrix. Results for plasma and erythrocytes agreed with those obtained by the conventional technique.

Erythrocytes↗
PubMed1981

Lead in preserved duck eggs: field screening test and confirmation and quantitation by atomic absorption spectrophotometry and anodic stripping voltammetry.

Analysis of preserved duck eggs in this laboratory by acid digestion and atomic absorption spectrophotometry has shown that addition of lead salts to the egg coating to speed the preservation process results in lead in the egg albumen and yolk. The lead levels decrease as the lead passes through successive membranes, i.e., the lead level in the yolk is lower than that in the albumen. A method has been developed for the field screening of preserved duck eggs for the presence of lead in which a portion of the egg coating is shaken with 4% acetic acid, and the resulting solution is tested by a modification of the AOAC dithizone method. A quantitative method for laboratory confirmation of lead in egg albumen and/or yolk has also been developed in which lead is determined by atomic absorption spectrophotometry or anodic stripping voltammetry after closed-system Teflon-cup digestion with nitric acid.

Animals↗
PubMed1993

[Study on dissolution rate and bioavailability of norfloxacin capsule by UV-spectrophotometry].

The dissolution rates and bioavailability of norfloxacin in seven batches of norfloxacin capsules produced by five pharmaceutical factories were studied with rotating basket and UV-spectrophotometry. The results showed that the T50, Td and m of the samples had obvious differences, and the correlation between the dissolution rate and bioavailability differed very obviously. The method used is simple and convenient. So UV-spectrophotometry is one of the methods for the assay of norfloxacin preparations in vitro and in vivo.

Biological Availability↗