title: Nitrite/nitrate detection in serum based on dual-plate generator-collector currents in a microtrench.
abstract: A dual-electrode sensor is developed for rapid detection of nitrite/nitrate at micromolar levels in phosphate buffer media and in dilute horse serum without additional sample pre-treatment. A generator-collector configuration is employed so that on one electrode nitrate is reduced to nitrite and on the second electrode nitrite is oxidised back to nitrate. The resulting redox cycle gives rise to a specific and enhanced current signal which is exploited for sensitive and reliable measurement of nitrite/nitrate in the presence of oxygen. The electrode design is based on a dual-plate microtrench (approximately 15 µm inter-electrode gap) fabricated from gold-coated glass and with a nano-silver catalyst for the reduction of nitrate. Fine tuning of the phosphate buffer pH is crucial for maximising collector current signals whilst minimising unwanted gold surface oxidation. A limit of detection of 24 μM nitrate and a linear concentration range of 200-1400 μM is reported for the microtrench sensor in phosphate buffer and dilute horse serum. Relative standard deviations for repeat measurements were in the range 1.8-6.9% (n=3) indicating good repeatability in both aqueous and biological media. Preliminary method validation against the standard chemiluminescence method used in medical laboratories is reported for nitrate analysis in serum.
authors.affiliation: Department of Chemistry, University of Bath, Bath BA2 7AY, UK. Electronic address: A.Gross@bath.ac.uk.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Gross
authors.affiliation: Department of Chemistry, University of Bath, Bath BA2 7AY, UK.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Holmes
authors.affiliation: Department of Chemistry, University of Bath, Bath BA2 7AY, UK.
authors.forename: Sara E C
authors.initials: SE
authors.lastname: Dale
authors.affiliation: University of Exeter Medical School, University of Exeter, St Luke׳s Campus, Exeter EX1 2 LU, UK.
authors.forename: Miranda J
authors.initials: MJ
authors.lastname: Smallwood
authors.affiliation: Department of Physics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QL, UK. Electronic address: S.J.Green@exeter.ac.uk.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Green
authors.affiliation: Department of Physics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QL, UK.
authors.forename: C Peter
authors.initials: CP
authors.lastname: Winlove
authors.affiliation: University of Exeter Medical School, University of Exeter, St Luke׳s Campus, Exeter EX1 2 LU, UK.
authors.forename: Nigel
authors.initials: N
authors.lastname: Benjamin
authors.affiliation: University of Exeter Medical School, University of Exeter, St Luke׳s Campus, Exeter EX1 2 LU, UK.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Winyard
authors.affiliation: Department of Chemistry, University of Bath, Bath BA2 7AY, UK.
authors.forename: Frank
authors.initials: F
authors.lastname: Marken
mesh_terms: D000818:Animals; D002384:Catalysis; D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D006736:Horses; D055616:Microtechnology / Q000295:instrumentation*; D009566:Nitrates / Q000097:blood*; D009573:Nitrites / Q000097:blood*; D012834:Silver / Q000737:chemistry*
chemical_list: D009566:Nitrates; D009573:Nitrites; D012834:Silver; D006046:Gold
keywords: Bipotentiostat; Electroanalysis; Electrochemical sensor; Microtrench; Nitrate; Serum