Manganese Detection Using Stencil-printed Carbon Ink Electrodes on Transparency Film

Mn concentrations were determined using square-wave cathodic stripping voltammetry (CSV) with inexpensive, stencil-printed carbon ink electrodes generated on polypropylene transparency films. Using an optimized pH5 ammonium acetate buffer and addition of 1,4-benzoquinone, a detection limit as low as 500 nM (30 ppb) was achieved. Addition of 1,4-benzoquinone improved peak potential reproducibility and height, while addition of 3.5% w/w sodium chloride to the background solution approximately doubled the sensitivity (mA/ppm). Tolerance tests with interfering metals were conducted and the method was found to be resilient to chromium(VI), iron(III), magnesium(II), nickel(II), and zinc(II), but susceptible to aluminum(III), copper(II), iron(II), and lead(II) at concentration ratios at or below one. This technique was successfully used to measure Mn levels in yerba mate and green tea samples as an example application.