Mehdi Taghdiri; Setareh Zakeri-Shahvari; Hamidreza Zare-mehrjardi
Abstract
The principle of this research is based on the development of multi-residue method by QuEChERS sample preparation follow by gas chromatography with mass spectrometric detection in the selected ion monitoring mode (GC–MS-SIM) for the routine analysis of 42 pesticides in rice samples. The rice samples ...
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The principle of this research is based on the development of multi-residue method by QuEChERS sample preparation follow by gas chromatography with mass spectrometric detection in the selected ion monitoring mode (GC–MS-SIM) for the routine analysis of 42 pesticides in rice samples. The rice samples were initially extracted with acetonitrile, and the targeted pesticides were purified following the dispersive solid phase extraction (d-SPE) cleanup method. The calibration curve for each analyte quantified by matrix-matched calibration was linear over the concentration range of 10.0–1000.0 μg L−1 with a correlation coefficient range between 0.990 and 0.999. Mean recoveries from three replicates ranged from 79% to 112%, with satisfactory precision (RSD<7%). The limit of detection and the limit of quantification were in the range of 3.04–12.52 μg L−1 and 10.14–41.76 μg L−1 respectively, for all 42 pesticides.
Hamidreza Zare-mehrjardi
Abstract
In this study, the surface of the glassy carbon electrode (GCE) is modified with the nanocomposite of graphene oxide (GO)/ ionic liquid (1-Butyl-3-methylimidazolium tetrafluoroborate; [BMIM]BF4). The electrochemical behavior of ascorbic acid (AA) and dopamine (DA) at the surface of the modified glassy ...
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In this study, the surface of the glassy carbon electrode (GCE) is modified with the nanocomposite of graphene oxide (GO)/ ionic liquid (1-Butyl-3-methylimidazolium tetrafluoroborate; [BMIM]BF4). The electrochemical behavior of ascorbic acid (AA) and dopamine (DA) at the surface of the modified glassy carbon electrode was studied using the differential pulse and cyclic voltammetric methods (DPV and CV). The results show good response sensitivity to AA and DA. The acceleration of the electron transfer rate and enhancement of the electroactive surface area is obtained due to a synergistic effect in the concurrent presence of GO and [BMIM]BF4 at the surface of the electrode. The presence of GO caused to a higher specific surface of the electrode, and ionic liquid ([BMIM]BF4) increased the ion conductivity and dispersibility in the modifier layer at the surface of the GCE. These results obtained in optimum conditions, show good peak separation for AA and DA (more than 300 mV), and the sub-micromolar detection limits for them. The obtained results in this work, make the modified GCE very effective in the manufacture of simple devices for the detection of AA and DA in human urine samples.
Hamid-Reza Zare-Mehrjardi
Abstract
Acridine orange supported on multi-walled carbon nanotube (MWCNT) is used for modification of carbon-paste electrode. The studies show that acridine orange efficaciously immobilized in the matrix of the electrode by applying nafion/MWCNT composite under the ultrasonic condition. The results of voltammetric ...
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Acridine orange supported on multi-walled carbon nanotube (MWCNT) is used for modification of carbon-paste electrode. The studies show that acridine orange efficaciously immobilized in the matrix of the electrode by applying nafion/MWCNT composite under the ultrasonic condition. The results of voltammetric experiments demonstrate that the prepared electrode has an effective response to DA and AA and a relatively big anodic peak separation (nearly 368 mV) is obtained for these compounds. Good sensitivity and selectivity and very low detection limit (0.03 µM) makes the modified electrode very effective in the manufacture of simple devices for the concurrent detection of dopamine in the presence of ascorbic acid in clinical and pharmaceutical preparations.
