Laser-pyrolyzed electrochemical paper-based analytical sensor for sulphite analysis

A CO2 laser can be used to pyrolyze the surface of common paperboard to produce a conductive carbon material for subsequent use as an electrode for general electrochemical measurements. In this work, a laser-pyrolyzed electrochemical paper-based analytical device (LP-ePAD) of this type was combined with a gas-diffusion microextraction (GDME) unit for the square-wave voltammetric analysis of sulphites in commercial beverages. The fabricated LP-ePAD had a resistivity at room temperature of 11 +/- 4 Omega per square electrical sheet (measured with a four-point probe system). The developed methodology showed a limit of detection of 1 mg L-1 for sulphite analysis, with good repeatability and reproducibility (coefficient of variation below 7%), as well having as the desirable qualities of portability and low price.