Polyaniline(PANI) chemically coated on poly(vinyl chloride) (PVC) membrane based on a neutral carrier 7,16-didecyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (kryptofix 22 DD) as the active component has been developed for determination of pH values ranging from pH 0.1-1. The effect of experimental parameters such as membrane composition, nature and amount of plasticizer, lipophilic additives and thickness of PANI film on the potential response of the pH electrode was investigated. The electrode has an apparent Nernstian response slope of 54.5 ± 0.4 mV pH^-1 (at 20°C). The equilibrium water content of the electrode was determined in pure water and NaCl solution (I = 0.1 mol Kg^-1). The electrode had low electric resistance, good potential stability and reproducibility (±1.5 mV, 𝑛 = 10). It has a rapid potential response to changes of pH (15 s). The excellent performance in terms of linearity, stability and fast response makes this device suitable for pH measurements in highly acidic media.

A simple procedure for the voltammetric detection of the DNA damage using a disposable electrochemical DNA biosensor is reported. The DNA biosensor is assembled by immobilizing the double stranded calf thymus DNA (dsDNA) on the surface of a disposable carbon screen-printed electrode. The interaction of 2-aminoanthracene (2-AA) with calf thymus dsDNA was studied electrochemically based on the oxidation signals of guanine (G) and adenine (A) by using square wave voltammetry (SWV) at screen printed electrode (SPE). The oxidation signals of the guanine and adenine bases, obtained by a square wave voltammetric scan, were used as analytical signal to detect the DNA damage. The presence of this aromatic amine compound with affinity for nucleic acids was measured by its effect on the guanine and adenine oxidation peaks. The response was obtained in the range of 0.05-20 mg L^-1 for 2-AA concentration on dsDNA-modified SPE. This test has been used due to its rapid, easy handling and cost effective responses for the toxicity assessment in real water and bleach solution samples.