Analytical Sciences

Effects of Polymerization and Hydrolysis Degrees of Poly(vinyl alcohol) (PVA) on the Efficiency of the PVA-Solid Substrate for Room-Temperature Phosphorimetry

Tatsuya KITADE,  Yutaka WADA, Shigehiko TAKEGAMI, Akiko KURODA, Shihori KISHI, and Keisuke KITAMURA

Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina, Kyoto 607-8414, Japan

Several kinds of poly(vinyl alcohols) (PVAs) having different degrees of polymerization and hydrolysis were tested as a material of a solid substrate for room-temperature phosphorimetry (RTP). Effects of these differences on the efficiency of the solid substrate were investigated. Completely hydrolyzed PVAs acquired a luminescence property in the grinding process of substrate preparation, but partially hydrolyzed PVAs did not acquire this property. When the completely hydrolyzed PVA substrates were prepared by drying their aqueous solutions, their luminescence property almost disappeared. However, very weak background emission remained on the surface of a completely dried substrate which had been treated with an analyte aqueous solution. This residual background affected the spectrum of the analyte, especially at low concentrations. Stability of the phosphorescence intensity with the passage of time was superior on the partially hydrolyzed PVAs than on the completely hydrolyzed PVAs. On the other hand, the RTP intensity and reproducibility were superior on the completely hydrolyzed PVAs. Practically, partially hydrolyzed PVAs were more suitable as a material of the substrate because of the stability of its RTP intensity and the weakness of its background emission. The linear dynamic range of the analytical curve for p-aminobenzoic acid on the substrate of partially hydrolyzed PVA having a degree of polymerization of 3500 was 5 - 2000 pmol/spot (20 uL) and its correlation coefficient was 0.963 for 30 data points.

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