Nitrite sensor based on multilayer film of Dawson-type tungstophosphate alpha-K7)[H4PW18O62]x18H2O immobilized on glassy carbon.

A nitrite sensor based on immobilized Dawson-type tungstophosphate alpha-K(7)[H(4)PW(18)O(62)].18H(2)O (PW(18)) in multilayers of charged polyelectrolyte poly(allylamine hydrochloride) (PAH) on a glassy carbon electrode is described. A nitrite sensor manufactured with 10 layers has a sensitivity of approximately 4 nA/microM nitrite, fast response time (<6s), low detection limit ( approximately 0.1 microM), high selectivity towards endogenous interferences such as nitrate and molecular oxygen, a linear range from 0.1 microM to at least 20mM nitrite and was stable for at least 2 months. In addition, such nitrite sensors can operate in a pH range from 1 to 9, and the sensitivity can be increased by increasing the number of layers at the expense of increasing the response time.