The electrochemical determination of formaldehyde in aqueous media using nickel modified electrodes

Glassy carbon (GC) electrodes were modified with nickel metal via a simple deposition procedure, followed by enrichment of the nickel in a potassium hydroxide solution to deliver the catalytic nickel hydroxide species (Ni(OH)(2)). In solutions of 1 M KOH, the nickel modified GC electrode (Ni-GC) contained a reproducible detection limit of the order of 1.1 x 10(-5) M for formaldehyde additions. This is comparable and, in many cases, surpasses, platinum group metal modified electrodes. The potentiometric analytical method also allowed for the accurate determination of unknown formaldehyde concentrations, over a linear range of 1 x 10(-5)-1 x 10(-3)M and a sensitivity of 22.7 +/- 3.8 A/mM. Furthermore, the Ni-GC electrode showed negligible response to formate and methanol, even when they were present in concentrations 10 times greater than the formaldehyde. The electrochemical performance was compared to a simple colorimetric approach to formaldehyde determination, wherein a detection limit of 6 x 10(-6) M was obtained.