Alaa S. Amin; Hesham El-Feky
Abstract
A highly selective optical sensor for V(IV) ions was established depended on entrapment of a sensitive reagent, 5-(2`,4`-dimethylphenylazo)-6-hydroxy-pyrimidine-2,4-dione (DMPAHPD), in a silica sol–gel thin film coated on a glass substrate. The thin films fabricated depended on tetraethoxysilane ...
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A highly selective optical sensor for V(IV) ions was established depended on entrapment of a sensitive reagent, 5-(2`,4`-dimethylphenylazo)-6-hydroxy-pyrimidine-2,4-dione (DMPAHPD), in a silica sol–gel thin film coated on a glass substrate. The thin films fabricated depended on tetraethoxysilane (TEOS) as precursor, sol–gel of pH = 2.5, water: alkoxyde ratio of 4: 1 and DMPAHPD concentration of 2.5 × 10−4 M. The effect of sol–gel parameters on sensing behavior of the fabricated sensor was also illustrated. The fabricated sensor can be used to detect V(IV) ion with an outstanding high selectivity over a wider dynamic range of 5.0–145 ng mL−1 and a detection limit of 1.35 ng mL−1. It also recorded reproducible results with relative standard deviation of 1.75% and 1.02% for 20 and 70 ng mL−1 of V(IV), respectively, along with a fast response time of two min. Total vanadium was determined after reduction of V(V) to V(IV) using ascorbic acid as reducing agent. The V(V) amounts were estimated by subtracting the concentration of V(IV) from the total vanadium concentration. Interference studies reported a good selectivity for V(IV) with trapping DMPAHPD into sol–gel matrix and appropriately adjusting the structure of doped sol–gel. The proposed sensor was compared with others and was applied to define vanadium in different environmental samples with good results.
Alaa S. Amin; Ahmed Alharbi
Abstract
Ionic liquid based ultrasound-assisted dispersive liquid–liquid microextraction of trace levels of Rh3+ ions from aqueous samples is illustrated, to investigate a rapid and reliable sample pretreatment to determine Rh3+ ions spectrophotometrically. The Rh3+ is converted into its complex with 5-(4`-chlorophenylazo)-6-hydroxy-pyrimidine-2,4-dione ...
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Ionic liquid based ultrasound-assisted dispersive liquid–liquid microextraction of trace levels of Rh3+ ions from aqueous samples is illustrated, to investigate a rapid and reliable sample pretreatment to determine Rh3+ ions spectrophotometrically. The Rh3+ is converted into its complex with 5-(4`-chlorophenylazo)-6-hydroxy-pyrimidine-2,4-dione (CPAHPD) as a complexing agent, and an ultrasonic bath is used with the ionic liquid, 1-octyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl) imide at room temperature is applied to extract the analyte. The centrifuged rhodium complex is enhanced in the form of ionic liquid droplets and prior to its spectrophotometric analysis, 250 µL ethanol is added to the ionic liquid-rich phase. Finally, the influence of various parameters on the recovery of Rh3+ is examined and optimized. Under optimum conditions, the calibration graph is linear in the range of 10–260 ng mL−1, the detection limit is 3.2 ng mL−1 (3Sb/m, n=7) and the relative standard deviation is ± 1.78 % (n=7, C = 150 ng mL−1). Comparison with other procedures, the proposed procedure reduces the danger of exposure to toxic solvents, applied for extraction in conventional extraction procedures, it also requires a shorter extraction time. The method is successfully validated by the analysis of real samples and compared statistically with FG-AAS method. The proposed method is successfully validated by the analysis different complex materials such as environmental water and alloy samples and compared statistically with ETAAS method.
