PHASE INVERSION CELLULOSE-ACETATE MEMBRANES FOR SUPPRESSION OF PROTEIN INTERFERENCES IN ANODIC-STRIPPING VOLTAMMETRY .2. IMPROVEMENT OF THEMEMBRANE PREPARATION PROCEDURE

Phase inversion (PI) cellulose acetate membranes were cast on glassy c arbon electrodes from a solution containing acetone as solvent and aqu eous magnesium perchlorate as pore former. It is shown that a signific ant improvement of the reproducibility and permselective properties of the membrane is obtained by allowing complete evaporation of the solv ent in a controlled humidity environment before the membrane is gelate d. By using cadmium and lead as test analytes and differential pulse a nodic stripping voltammetry as the detection method, it was found that the modification of the electrode greatly reduces the interference fr om albumin, lysozyme, gelatin and polyethylene glycol (MW 6000). The p ermselectivity of the PI membrane can be controlled by varying the amo unt of magnesium perchlorate in the casting solution and the relative humidity during the pre-gelation conditioning of the membrane.