A sensitive conductivity sensor for arsenic detection in environmental samples

Arsenic is a poisonous contaminant affecting the environment as well as living beings, thus its determination is critical. The study describes the designing and fabrication of a conductometric biosystem for the indirect identification of arsenic in aqueous samples. The principle of detection is based on the measurement of the inhibition of immobilized papain catalytic efficiency in the presence of arsenic. A linear response against arsenic trioxide (as trivalent inorganic arsenic is toxic) by the developed biosystem was found in the range of 0.1–20 ppm (correlation coefficient = 0.96) with the lower limit of detection of 5 ppb. For optimum working conditions and the response of the designed biosystem, different parameters were optimized such as substrate concentration (14 mM), pH (7), and temperature around (35 °C ± 5 °C). The resultant data were statistically evaluated by analysis of variance and were found to be significant at α = 0.05 with a recovery rate of 101.6%. The biosystem displayed a high recovery with a lower detection limit, thus it can be utilized for environmental arsenic trioxide estimation. • The report describes the development and fabrication of an inhibition based electrochemical biosensor • Enzyme papain is used to design the biosensor which shows the inhibition in response to its reaction with arsenic. • This change in the inhibition activity is the measure of analyte concentration. • The designed biosensor has the LOD of 5 ppb.