Measurement of free copper(II) ions in water samples with polyvinyl alcohol as a binding phase in diffusive gradients in thin-films.

A technique for the selective measurement of diffusive gradients in thin-films (DGT) for free Cu2+ ions was developed using a 0.030 M solution of polyvinyl alcohol (PVA) as the liquid binding phase with the liquid-type DGT devices (PVA DGT). The PVA DGT had a substantial binding capacity at pH 5.6 - 8.6 and concentrations of competitive Na+ up to 0.7 M. The measurements of PVA DGT and cupric ion selective electrode (Cu-ISE) for free Cu2+ in synthetic river water (recovery = 97.51 +/- 2.58% for PVA DGT and recovery = 98.25 +/- 1.46% for Cu-ISE), in spiked river water (recovery = 24.99 +/- 3.55% for PVA DGT and recovery = 26.32 +/- 3.33% for Cu-ISE) and in spiked industrial wastewater (recovery = 4.21 +/- 3.13% for PVA DGT and recovery = 5.10 +/- 2.78% for Cu-ISE) were equivalent. The results showed that PVA DGT could measure selectively the free Cu2+ ion concentrations in water samples.