Graphene-Chitosan Composite Modified Electrode for Simultaneous Detection of Nitrophenol Isomers

Abstract

The graphene-chitosan composite film modified glassy carbon electrode (GR-CS/GCE) was prepared for the simultaneous detection of p-nitrophenol (p-NP) and o-nitrophenol (o-NP). GR-CS/GCE showed good electrocatalytic activity for the reduction of p-NP and o-NP. Under the optimized detection conditions, p-NP exhibited a linear detection range of 0.1∼140 μM with the detection limit (S/N = 3) of 0.09 μM at GR-CS/GCE, while 1∼240 μM for o-NP with a detection limit of 0.1 μM. The GR-CS demonstrated as a promising sensor material for the simultaneous detection of nitrophenol isomers.Nitrophenols are extensively employed in pharmaceutical, dye and pesticide industry. 1-3 The nitrophenol isomers such as p-nitrophenol (p-NP) and o-nitrophenol (o-NP) have serious impact on the growth and metabolic activities of living organisms. 4-6 Both p-NP and o-NP are therefore listed as the hazardous wastes and priority toxic pollutants. 7-9 The development of simple and effective methods for the detection of nitrophenol isomers is thus very important. To date, various analytical techniques have been employed for the detection of nitrophenol isomers, which include fluorescence, 10 high performance liquid chromatography, 11,12 spectrophotometry, 13,14 capillary electrophoresis 7 and electrochemistry. 15,16 Electrochemical approaches are becoming more attractive, due to their high accuracy, fast response and simple instrumentation. 17,18 To obtain higher sensitivity, the working electrodes are generally surface-modified with carbon nanotubes, 19 nano-gold, 16 reduced graphene oxide, 20 cyclodextrin (CD) functionalized mesoporous silica 21 and ordered mesoporous carbon. 22 These modified electrodes have been satisfactorily employed for the detection of nitrophenol isomers. However, the fabrication of new electrochemical electrodes with both sensitivity and wide linear detection range is still very challenging for the detection of nitrophenol isomers.Graphene (GR), two-dimensional sp 2 -hydridized carbon nanosheets, has attracted extensive attention since its discovery. 23 Due to its unique structure and excellent electrocatalytic activity, 24 GR based composites have been widely employed as electroactive materials for electrode modification. 25,26 The pristine GR is not good for electrochmical application due to its aggregation of nanosheets in bulk. 27 The β-cyclodextrin functionalized GR nanosheets was employed for the electrochemical detection of o-Nitrophenol, with a detection limit of 0.3 μM and a linear detection range of 5∼400 μM achieved. 28 To further increase the sensitivity of GR modified electrodes for electrochemical analysis, the well exfoliation of GR nanosheets is proved to be crucial. For this purpose, chitosan (CS) is used to stabilize exfoliated GR nanosheets for electrode modification. With abundant -OH and -NH 2 (or O = C-NH 2 ) groups present on its backbone, CS is advantageous as a dispersion agent by constructing hydrogen bonds and electrostatic interactions with the corresponding substrates. 29,30 The CS/GR composi...

Recent Developments in Polymer Nanocomposite-Based Electrochemical Sensors for Detecting Environmental Pollutants

“…Tang et al procured the Gr-CHIT composite film-modified GCE (Gr-CHIT/GCE) for the simultaneous detection of o -NP and para-nitrophenol p -NP) and investigated the electrochemical behavior of p -NP and o -NP by CV; the modified GCE displayed very good electrocatalytic activities to reduce p -NP and o -NP. Using LSV method, p -NP exhibited the linear determination ranges from 0.1–140 μM with an LOD of 0.09 μM (S/N = 3) at G-CHIT/GCE, while 1–240 μM for o -NP with the LOD equal to 0.1 μM.…”

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