scholarly journals Simultaneous Determination of Parathion, Malathion, Diazinon, and Pirimiphos Methyl in Dried Medicinal Plants Using Solid-Phase Microextraction Fibre Coated with Single-Walled Carbon Nanotubes

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Reza Ahmadkhaniha ◽  
Nasrin Samadi ◽  
Mona Salimi ◽  
Parisa Sarkhail ◽  
Noushin Rastkari
Keyword(s):  
Carbon Nanotubes ◽  
Solid Phase Microextraction ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Organophosphorus Pesticides ◽  
Single Walled Carbon Nanotubes ◽  
Single Walled Carbon ◽  
Pirimiphos Methyl ◽  
Walled Carbon Nanotubes

A reliable and sensitive headspace solid-phase microextraction gas chromatography-mass spectrometry method for simultaneous determination of different organophosphorus pesticides in dried medicinal plant samples is described. The analytes were extracted by single-walled carbon nanotubes as a new solid-phase microextraction adsorbent. The developed method showed good performance. For diazinon and pirimiphos methyl calibration, curves were linear (r2≥0.993) over the concentration ranges from 1.5 to 300 ng g−1, and the limit of detection at signal-to-noise ratio of 3 was 0.3 ng g−1. For parathion and malathion, the linear range and limit of detection were 2.5–300 (r2≥0.991) and 0.5 ng g−1, respectively. In addition, a comparative study between the single-walled carbon nanotubes and a commercial polydimethylsiloxane fibre for the determination of target analytes was carried out. Single-walled carbon nanotubes fibre showed higher extraction capacity, better thermal stability (over350∘C), and longer lifespan (over 250 times) than the commercial polydimethylsiloxane fibre. The developed method was successfully applied to determine target organophosphorus pesticides in real samples.

Nanostructured cobalt phthalocyanine single-walled carbon nanotube platform: electron transport and electrocatalytic activity on epinephrine

2008 ◽  
Vol 12 (12) ◽  
pp. 1289-1299 ◽  
Author(s):  
Bolade O. Agboola ◽  
Alfred Mocheko ◽  
Jeseelan Pillay ◽  
Kenneth I. Ozoemena
Keyword(s):  
Carbon Nanotubes ◽  
Electrocatalytic Activity ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Pyrolytic Graphite ◽  
Single Walled Carbon Nanotubes ◽  
Cobalt Phthalocyanine ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

The fabrication, characterization and application of edge-plane pyrolytic graphite electrode modified with acid-functionalized single-walled carbon nanotubes, nanostructured cobalt phthalocyanine and a mixture of both, towards epinephrine detection and analysis are described. The morphological features of the films were evaluated using atomic force microscopy (AFM). Electrochemistry of these electrodes in [ Fe ( CN )6]3−/4− using cyclic voltammetry and electrochemical impedance spectroscopy showed higher peak current responses with accompanying low electron-transfer resistances in comparison to the bare electrode. The edge-plane pyrolytic graphite-single-walled carbon nanotubes-nanostructured cobalt phthalocyanine electrode exhibited good electrocatalytic activity towards epinephrine oxidation with enhanced peak currents. Analytical studies using edge-plane pyrolytic graphite-single-walled carbon nanotubes-nanostructured cobalt phthalocyanine electrode proved that the electrode is suitable for sensitivity determination of epinephrine in pH 5 conditions judging from the good sensitivity (8.71 ± 0.31 A.M−1), and limit of detection (0.04 µM) and quantification (1.31 µM) obtained. Determination of EP in the absence and presence of ascorbic acid in phosphate buffer pH 5 conditions was carried out and it was established that the presence of AA did not interfere in EP analysis. Rotating disk electrode experiments proved that the catalytic rate constant was 2.28 × 1016 mM−1.s−1.

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