Quantifying Primary Silver Ions Contents in Poly(vinyl chloride) and Poly(n-butyl acrylate) Ion-Selective Membranes

On a model example of silver selective, poly(vinyl chloride) (PVC) or poly(n-butyl acrylate) based plastic membranes, a method of primary ions quantification has been proposed. For this purpose the inductively coupled plasma mass spectrometry with laser ablation (LA ICP MS) was used. Significant differences of the ions distribution between examined membranes materials were observed. For both kinds of membranes the influence of the concentration of AgNO(3) in conditioning solution was noticed. Conditioning in 0.1 M Solution resulted in a few times higher silver levels compared to expected for 100 mol% membrane saturation (relative to lipohilic salt content). This points to pronounced co-extraction of quite lipophilic nitrate anions. In the case of poly(n-butyl acrylate) based membranes, silver was accumulated mainly in the surface domain of the membrane, due to low mobility of silver ions in this material. This was experimentally proved by concentration profiles of silver across the poly(n-butyl acrylate) membrane, showing a lower contents inside the membrane, being in contrast to uniform distribution in PVC based matrix. The obtained silver contents in the membranes correlates well with potentiometric characteristic, low contents of silver corresponds to super-Nernstian responses in low Ag(+) activities range, for about 75% of saturation the detection limit close to 10(-8) M is obtained, 100% saturation or even higher silver contents results in micromolar detection limits.