Phase inversion cellulose acetate membranes for suppression of protein interferences in anodic stripping voltammetry .2. Improvement of the membrane preparation procedure

Phase inversion (PI) cellulose acetate membranes were cast on glassy carbon electrodes from a solution containing acetone as solvent and aqueous magnesium perchlorate as pore former. It is shown that a significant improvement of the reproducibility and permselective properties of the membrane is obtained by allowing complete evaporation of the solvent in a controlled humidity environment before the membrane is gelated. By using cadmium and lead as test analytes and differential pulse anodic stripping voltammetry as the detection method, it was found that the modification of the electrode greatly reduces the interference from albumin, lysozyme, gelatin and polyethylene glycol (MW 6000). The permselectivity of the PI membrane can be controlled by varying the amount of magnesium perchlorate in the casting solution and the relative humidity during the pre-gelation conditioning of the membrane.