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Voltammetric behavior of p-nitrophenol and its trace determination in human urine by liquid chromatography with a dual reductive mode electrochemical detection system

Honeychurch, Kevin C.; Hart, John P.

Authors



Abstract

The determination of trace p-nitrophenol (PNP) concentrations in human urine has been successfully achieved by high performance liquid chromatography dual electrode detection (LC-DED) in the reduction-reduction mode. Initial cyclic voltammetric studies were undertaken to investigate the electrochemical behavior of PNP at a glassy carbon electrode over a wide pH range; the redox processes giving rise to the signals have been deduced. Further, deductions regarding the behavior in the flow cells were made from hydrodynamic voltammetric data. PNP eluting from the analytical LC column is first reduced to p-hydroxylaminophenol, at the first generator electrochemical cell. This species then undergoes chemical oxidation to give a quinoneimine species which is then detected at the downstream detector electrode using an applied potential of -0.1 V. The optimum chromatographic mobile phase consisted of 40% acetonitrile, 60% water, containing 25 mM o-phosphoric acid, at a flow rate of 0.5 mL/min; this was used in conjunction with a Hypersil C18 column. Hydrodynamic voltammetric studies were undertaken to investigate the dual electrode behavior of PNP, and an applied potential of -2.0 V at the generator cell and -0.10 V at the detector cell were found to be optimum. The response was found to be linear over the range 7.0 ng to 500 ng on column, with an associated R2 value of 0.9981; the limit of detection was found to be 1.0 ng PNP on column. No interferences were seen for a number of common drugs or for the principal electrochemically active components of human urine or serum. The developed assay was successfully applied to the determination of trace concentrations of PNP in human urine samples, exhibiting coefficients of variation of 7.1% (n = 7), with a mean recovery of 94.7% for urine fortified at 522 ng mL-1. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.

Citation

Honeychurch, K. C., & Hart, J. P. (2007). Voltammetric behavior of p-nitrophenol and its trace determination in human urine by liquid chromatography with a dual reductive mode electrochemical detection system. Electroanalysis, 19(21), 2176-2184. https://doi.org/10.1002/elan.200703989

Journal Article Type Article
Publication Date Nov 1, 2007
Journal Electroanalysis
Print ISSN 1040-0397
Electronic ISSN 1521-4109
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 19
Issue 21
Pages 2176-2184
DOI https://doi.org/10.1002/elan.200703989
Keywords urine, HPLC, dual electrode detection, p-nitrophenol
Public URL https://uwe-repository.worktribe.com/output/1033097
Publisher URL http://dx.doi.org/10.1002/elan.200703989