Sensitive voltammetric response of methylparathion on single-walled carbon nanotube paste coated electrodes using ionic liquid as binder

An ionic liquid (i.e. 1-butyl-3-methylimidazolium hexafluophosphate, BMIMPF6)–single-walled carbon nanotube (SWNT) paste coated glassy carbon electrode (BMIMPF6–SWNT/GCE) has been fabricated. The electrode shows good electro-catalysis to the reduction of methylparathion (MP) and MP can accumulate effectively on it. Thus, MP can produce a sensitive cathodic peak on the BMIMPF6–SWNT/GCE. Parameters influencing the voltammetric response of MP are optimized for MP determination. Under the selected experimental conditions (i.e. solution pH 7.0; accumulation time, 180 s; accumulation potential, on open-circuit; the ratio of SWNT to BMIMPF6 1:20 (mg μL−1)), the peak current is linear to MP concentration over the range of 2.0 × 10−9 to 4.0 × 10−6 M. The detection limit is 1.0 × 10−9 M. Therefore, this system is quite sensitive in comparison with other electrochemical methods. In addition, it is found that the hydrolysate of MP (i.e. p-nitrophenol, PNP) can also produce a sensitive cathodic peak under this condition. But the peaks of MP and PNP do not overlap with each other. Hence they can be determined simultaneously. This electrode has been applied to the determination of MP and PNP in real samples.