Author(s): P.A.D. Nisansala, M.N. Kaumal
This paper reports the development of a simple, sensitive and low-cost microfluidic paper-based electrochemical sensing device developed for the detection of vitamin B12 in foods and pharmaceutical products. This hydrophobic barrier device was constructed on paper using commercially available varnish paint. The working electrode was constructed using a mixture of varnish and graphite powder. Silver conductive ink and a 6B pencil were used to fabricate the reference and counter electrodes, respectively. Cyclic voltammograms of standard vitamin B12 and real samples were collected from -2 V to +2 V at a scan rate of 200 mV/s. Currents of cyclic voltammograms at +2 V for the concentrations of vitamin B12 from 5 – 25 mM produced a linear relationship (r2 of 0.98). The calculated limit of detection of this paper-based device is 3.7 mM.