Full Paper Determination of ultra trace of thiosemicarbazide by adsorptive stripping voltammetric method (original) (raw)
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2019
According to the advantages of electrochemical analysis like high selectivity, high sensitivity, low analyte concentration, cost-effective, portable and easy-to-use setup, this method has attracted a great amount of attention among scientists for determination of different compounds. in this work, a simple, inexpensive, and rapid electrochemical method for the determination of thiosemicarbazide (TSC) was developed by using the modified glassy carbon electrode with multi-walled carbon nanotubes (MWCNT/GCE). Cyclic voltammetry (CV) studies indicated that TSC had a sensitive irreversible oxidative peak at 0.7 V. Compared to the untreated electrode, the modified electrode showed a negative shift in the oxidation peak of TSC. Differential pulse voltammetry on MWCNT/GCE showed a linear dependence on the concentration of TSC in the range of 1 × 10-6-100 × 10-6 M with a limit of detection (LOD) of 0.6 × 10-6 M. The proposed method was successfully applied to the determination of TSC in city...
The Analyst, 1996
A preliminary study of the indirect cathodic stripping voltammetric determination of 2-mercaptobenzothiazole (MBT) based on accumulation of its mercury, copper(1) and nickel(I1) salts or complexes was made as part of a wider study comparing these three related techniques of determining thiols. Detection limits for MBT using the copper@) and nickel(I1) methods (c 2 X considerably lower than that for the mercury method (about 3 x lo-' moll-1). The mercury method is susceptible to interference from copper(I1) and large amounts of nickel(@, and seems generally to be less reliable for the determination of MBT. The change from accumulation as the mercury salt to accumulation as the copper(1) salt is illustrated in the presence of excess of MBT over copper(@ with increasing copper(I1) concentrations, and with change of accumulation potential to more negative values from +lo0 mV. In the presence of a stoichiometric amount or excess of copper(I1) over MBT, no mercury salt is accumulated at potentials more negative than +50 mV. Currents obtained for MBT with the nickel(I1) method are much higher than those obtained previously with cysteine and penicillamine.
Electroanalysis, 2005
This work describes a very sensitive and selective voltammetric procedure for the determination of platinum. Instead of commonly used hydrazine, thiosemicarbazide as a component of supporting electrolyte was applied. The method is based on adsorption of platinum-thiosemicarbazone complex, formed in situ in voltammetric cell from thiosemicarbazide and formaldehyde, coupled with a hydrogen catalytic reaction at a hanging mercury drop electrode. The linear relation between platinum concentration and height of analytical signal was observed up to 1.5 Â 10 À9 mol L À1 with the detection limit calculated as 1.5 Â 10 À13 mol L À1 (3 s of the blank) after 50 s of accumulation time. The effect of various interferences from other ions was studied. Described method was applied for platinum determination in hydroponically cultivated plants after microwave decomposition.
Journal of Pharmaceutical and Biomedical Analysis, 2002
The adsorptive and electrochemical behavior of trimetazidine hydrochloride on a glassy carbon electrode were investigated in acetate buffer solution by using cyclic and square-wave voltammetry. Cyclic voltammetric studies indicated the oxidation of trimetazidine hydrochloride at the electrode surface through a single two-electron irreversible step and fundamentally controlled by adsorption. The solution condition and instrumental parameters were optimized for the determination of the authentic drug using adsorptive square wave stripping voltammetry. Trimetazidine hydrochloride gave a sensitive adsorptive oxidative peak at 0.750 V (vs. Ag/AgCl). The oxidation peak was used to determine authentic trimetazidine hydrochloride concentration in the range 5.0 × 10 − 8-5.0×10 − 6 M with a detection limit of 2.0 × 10 − 8 M. The procedure was successfully applied for assay of trimetazidine hydrochloride in the tablet dosage form (Vastarel). A mean recovery of 94.7% with a relative standard deviation (R.S.D.) of 0.88% was obtained. Applicability to assay the drug in urine samples was illustrated. The peak current was linear with the drug concentration in the range 17-85 mg per ml urine. The detection limit was 1.7 mg ml − 1 urine.
Journal of Chromatography, 1986
Twenty-five thiobenzamide derivatives were separated on a reversed-phase system on various stationary phases, with UV photometric and voltammetric detection. The best results were obtained using a Partisil ODS column (10 pm, 250 mm x 4.6 mm I.D.) with a mobile phase consisting of 0.05 M sodium dihydrogen phosphate with 30% (v/v) methanol, containing 1.2 . lop4 A4 EDTA, at a flow-rate of 1 .O ml/min. Voltammetric detection on a carbon-fibre electrode at + 1.4 V (silver-silver chloride) is more sensitive than UV photometric detection at 254 nm, typical detection limits being cu. 0.1 and 1 .O ng. Voltammetric calibration curves exhibit good linearity and the measurements are reproducible (relative standard deviation of cu. 2%).
Analytica Chimica Acta, 2000
A simple and more sensitive cathodic stripping voltammetric method is described for the determination of short-anaesthetic drug thiopentone−sodium (TPS). The method is based generally on the formation of a slightly soluble mercury salt of TPS with Hg onto HMDE surface. The reduction current of the formed salt was measured by both linear sweep (LSCSV) and differential pulse cathodic stripping voltammetry (DPCSV). Different variables were studied and optimized. Four-fold enhancement in the current is observed in the presence of trace Mg ion. The role of Mg ion is discussed in a manner that hydroxide species are formed and accelerate the adsorption of the drug. As low as 1×10 −8 mol l −1 (2.60 ppb) and 2×10 −9 mol l −1 (0.53 ppb) with accumulation time 240 and 300 s, in the absence and in the presence of Mg(II), respectively, have been determined using both techniques, with the relative standard deviation up to 3.5% (n=4). The interferences of some metal ions, ascorbic acid and amino acids were studied. The determination of the drug in pure pharmaceutical dosage form, urine, and human serum samples have been successfully carried out. The results were compared favorably with the official methods.
Microchimica Acta, 2001
A sensitive method for the determination of amitraz pesticide at nanomolar level by adsorptive stripping voltammetry at a hanging mercury drop electrode is described. The cyclic voltammograms demonstrate the adsorption of this compound on the mercury electrode. A systematic study of the various experimental parameters, that affect the stripping response, was carried out by differential pulse voltammetry. Using an accumulation potential of À0.50 V, and 30 s accumulation time, the limit of detection was found to be 2X3 Â 10 À9 mol L À1 and the relative standard deviations (n 5) was 2.2% at concentration level of 5X0 Â 10 À8 mol L À1 of amitraz. The in¯uence of diverse ions and some other pesticides was investigated. Finally, the method was applied to the determination of amitraz in spiked soil and water. The relative standard deviation is 4.5% for 5 determinations of amitraz in water and 3.2% for 5 determinations in soil.