Amperometric Nitric Oxide Sensors: a Comparative Study

Abstract

A comparative study among different types of modified electrodes for nitric oxide (NO) determination has been carried out. Detection limit, response time, reproducibility and selectivity versus some interferents as ascorbic acid, nitrite and dopamine were evaluated. Platinum (Pt) and glassy carbon (GC) electrodes have been assembled with homemade cellulose acetate membranes, commercially available membranes, Nafion and nonconducting polymers electrosynthesized directly onto the electrode surface. The most interesting results were obtained with a cellulose acetate membrane modified electrode and a Pt/poly[4,4 0 -dihydroxybenzophenone (4,4 0 -DHB)] electrode. The NO probes assembled showed a detection limit of 20 nmol/L and 40 nmol/L, respectively, for the cellulose acetate membrane modified electrode and for the Pt/poly[4,4 0 -dihydroxybenzophenone (4,4 0 -DHB)] electrode. A biological test on washed platelets stimulated by collagen was performed using the Pt/poly(4,4 0 -DHB) electrode.

Calibration of NO sensors for in-vivo voltammetry: laboratory synthesis of NO and the use of UV?visible spectroscopy for determining stock concentrations

“…The current was then measured when the solution was quiescent. The electrodes were held at a constant potential of +900 mV [19]. All calibrations were performed at room temperature.…”

“…Because the concentration of saturated NO solution at room temperature has been reported to be 1.9 mmol L À1 in the literature [19,[36][37][38][39][40] we decided to examine the possibility that our stock NO solution contained species other than NO which might be preventing a saturated concentration being obtained.…”

“…The first method involves the preparation of NO standard solutions from pure NO gas obtained by buying a commercial cylinder with a stainless-steel regulator. However, although this is the most commonly used method for NO sensor calibration found in the literature [16][17][18][19][20][21][22], it suffers from a number of drawbacks including expense and shelf-life.…”

“…In addition, while reviewing the literature it became apparent that many research groups working with NO standard solutions used no experimental method to verify the concentration of their stock solution, instead quoting saturation concentrations found in the literature -ca. 1.9 mmol L À1 at room temperature [19,[36][37][38][39][40]. Because of the reactivity of NO with molecular oxygen, and its high permeability characteristics [41], it should be considered important for research groups working with NO to verify their stock concentration.…”

On the Electrooxidation and Amperometric Detection of NO Gas at the Pt/Nafion® Electrode

“…A variety of sensing electrode, usually made of platinum and carbon electrodes or their composites, is mainly used for amperometric NO liquid sensing, for example, in the phosphate buffer solution. The electrodes employed include Pt/Nafion ® [1][2], Pt/Nafion ® /cellulose acetate [1], Pt/Ir [3], Pt/poly(4,4'-DHB) [4], C/NiP/Nafion ® [5][6], C/Nafion ® [2,[7][8][9], C/silicon [10], and M(salen)/Nafion ® [11]. Table 1 summarizes the operating condition, NO concentration range, and detection limit in the solution phase studied on various sensing electrodes.…”