A new optical chemical sensor is established for sensitive and selective spectrophotometric detection of copper based on the immobilization of 3‐(2‐methyl‐2,3‐dihydro‐1,3‐benzothiezol‐2‐yl)‐2H‐chromen‐2‐one on a triacetylcellulose membrane. Copper ions react with the immobilized ligand and cause an increase in the absorption of the membrane at 550 nm in universal buffer solution at pH = 6. The effects of pH, indicator concentration and reaction time on the immobilization of the ligand were studied. This optode exhibits a linear range of 7.0 × 10−7 to 1 × 10−4 mol l−1 of copper ion concentration with a limit of detection of 3.0 × 10−7 mol l−1. The response time of the newly designed optode is within 3 min. The effect of different possible interfering species was investigated and it was found that the sensor has very good selectivity. The proposed sensor benefits from advantages such as low cost, high stability, low detection limit, fast response time, reproducibility, relatively long lifetime, and good selectivity for Cu2+ ion determination among a large number of alkali, alkaline earth, transition and heavy metal ions. The sensor can readily be regenerated with thiourea solution and its response is reversible and reproducible (relative standard deviation < 1.4%). The proposed optode was applied successfully for the determination of Cu(II) in various samples.
A rapid and simple method for the extraction and preconcentration of ceftazidime in aqueous samples has been developed using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography analysis. The extraction parameters, such as the volume of extraction solvent and disperser solvent, salt effect, sample volume, centrifuge rate, centrifuge time, extraction time, and temperature in the dispersive liquid-liquid microextraction process, were studied and optimized with the experimental design methods. Firstly, for the preliminary screening of the parameters the taguchi design was used and then, the fractional factorial design was used for significant factors optimization. At the optimum conditions, the calibration curves for ceftazidime indicated good linearity over the range of 0.001-10 μg/mL with correlation coefficients higher than the 0.98, and the limits of detection were 0.13 and 0.17 ng/mL, for water and urine samples, respectively. The proposed method successfully employed to determine ceftazidime in water and urine samples and good agreement between the experimental data and predictive values has been achieved.
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