Reduction peaks in single drop square wave polarography (SDSWP) for metal ions such as Cd(II) and Pb(II) in the presence of picolinic acid gave peak currents that can be an order of magnitude or more greater than diffusion-limited peaks. Various studies using techniques such as controlled-potential electrolysis, tast polarography, staircase voltammetry, and SDSWP demonstrated that this enhancement effect was due to the adsorption of metal–picolinate complexes on the electrode surface. Since it provides a detection limit of about 0.2 ppb with ions such as Cd(II), adsorption enhancement appears to be of use in trace analysis under certain circumstances. Linearity is observed only up to 1 × 10−5 M and any substance capable of adsorption is a potential interferent.