جستجوی مقالات مرتبط با کلیدواژه « Spectrofluorimetry » در نشریات گروه « شیمی »

In the present study, a simple, rapid and efficient dispersive liquid–liquid microextraction (DLLME) coupled with spectrofluorimetry (SFM) and chemometrics methods have been proposed for the preconcentration and determination of fenthion in water samples. Box–Behnken design was applied for multivariate optimization of the extraction conditions (sample pH, the volume of dispersive solvent and volume of extraction solvent). Analysis of variance was performed to study the statistical significance of the variables, their interactions and the model. Under the optimum conditions, the calibration graph was linear in the range of 5.0–110 ng mL-1 with the detection limit of 1.23 ng mL-1 (3Sb/m). Parallel factor analysis (PARAFAC) and partial least square (PLS) modelling were applied for the multivariate calibration of the spectrofluorimetric data. The orthogonal signal correction (OSC) was applied for preprocessing of data matrices and the prediction results of model, and the analysis results were statistically compared. The accuracy of the methods, evaluated by the root mean square error of prediction (RMSEP) for fenthion by OSC-PARAFAC and OSC-PLS models were 0.37 and 0.78, respectively. The proposed procedure could be successfully applied for the determination of fenthion in water samples.

A new analytical approach was developed involving magnetic solid–phase extraction and spectrofluorimetric determination of carvedilol in human plasma samples. A plasma sample was prepared and adjusted to pH 8.2–10, then carvedilol was quickly extracted using iron oxide magnetic nanoparticles modified by the surfactant cetyltrimethylammonium bromide and determined to apply spectrofluorimetry at 354 ± 3 nm after excitation at 241 ± 3 nm. Experimental conditions, such as the amount of nanoparticles and cetyltrimethylammonium bromide, pH value, standing time and desorption solvent type and volume have been adjusted to optimize the extraction process and to obtain analytical characteristics of the method. Linearity was observed in the analyte concentration range of 2.0–125 ng/mL with correlation coefficients (r) of 0.999.
The method showed good precision and accuracy, with intra– and inter–assay precisions of less than 7.0% at all concentrations. Standard addition recovery tests were carried out, and the recoveries ranged from 94.4% to 100.7%. The limits of detection and quantification were found to be 0.67 and 2.24 ng/mL. The method was applied to the determination of carvedilol in human plasma samples.

A method based on the ultrasound-assisted solidification of floating drop microextraction technique was developed for the spectrophotometric and spectrofluorimetric determination of curcumin in turmeric powder. In this work a small volume of an organic solvent was floated on the surface of an aqueous solution. After sonication the organic solvent is solidified and separated. The effect of extraction parameters such as type and the volume of organic solvent, temperature, salt addition and exposure time, on the extraction recovery was investigated and optimized. Finally, the method droplet was used for the determination of analyte. Under the optimum extraction conditions, a linear range of 0.006–30 μg mL-1 and a relative standard deviation (RSD) of 2.72% for curcumin wasachieved. Limits of detection of 7 and 2 ng mL-1 curcumin was obtained for the spectrophotometric and spectrofluometric methods, respectively. The obtained results show that the application of this method can be successful for the analysis of curcumin in turmeric powder samples.

In this work, an environmentally friendly sample pre-treatment method, Ultrasound Assisted Surfactant Enhanced Emulsification Microextraction (UASEME) followed with spectrofluorimetry was performed for determination of oxadiazon residues in water samples. After the determination of the most suitable extraction solvent and its volume, other parameters such as type and concentration of surfactant, pH, extraction time and ionic strength were optimized. Under the best conditions for extraction recovery, 50µL of chlorobenzene was chosen as extraction solvent and Tween 20 in concentration of 0.06 mmol/L as emulsifier and 2 min was the required time for quantitative analysis, without ionic strength and pH adjustment. Limit of detection and relative standard deviation were calculated as 0.05µg/L and 3.2% respectively. The procedure was applied successfully for assessing matrix effect in real water samples with relative recovery 96-104% with the precision in the range of 2.9-3.4%. The results demonstrate that UASEME procedure as reported is reliable, rapid and easy to use for analysis of oxadiazon in water samples.