Room temperature phosphorescence of biogenic indoles in low background paper enhanced by heavy atom salts and sodium dodecyl sulfate

A new analytical application of nylon-induced room-temperature phosphorescence: Determination of thiabendazole in water samples

This paper discusses the first analytical determination of the widely used fungicide thiabendazole by nylon-induced phosphorimetry. Nylon was investigated as a novel solid-matrix for inducing room-temperature phosphorescence of thiabendazole, which was enhanced under the effect of external heavy-atom salts. Among the investigated salts, lead(II) acetate was the most effective in yielding a high phosphorescence signal. An additional enhancement of the phosphorescence emission was attained when the measurements were carried out under a nitrogen atmosphere. There was only a moderate increase in the presence of cyclodextrins. The room-temperature phosphorescence lifetimes of the adsorbed thiabendazole were measured under different working conditions and, in all cases, two decaying components were detected. On the basis of the obtained results, a very simple and sensitive phosphorimetric method for the determination of thiabendazole was established. The analytical figures of merit obtained under the best experimental conditions were: linear calibration range from 0.031 to 0.26 microg ml(-1) (the lowest value corresponds to the quantitation limit), relative standard deviation, 2.4% (n=5) at a level of 0.096 microg ml(-1), and limit of detection calculated according to 1995 IUPAC Recommendations equal to 0.010 microg ml(-1) (0.03 ng/spot). The potential interference from common agrochemicals was also studied. The feasibility of determining thiabendazole in real samples was successfully evaluated through the analysis of spiked river, tap and mineral water samples.

Effects of polymerization and hydrolysis degrees of poly(vinyl alcohol) (PVA) on the efficiency of the PVA-solid substrate for room-temperature phosphorimetry

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 3,500 was 5-2,000 pmol/spot (20 microL) and its correlation coefficient was 0.963 for 30 data points.

Analytical method based on room-temperature phosphorimetry for the determination of rescinamine in pharmaceutical tablets

An analytical method based on solid surface room temperature phosphorescence (SSRTP) for the determination of rescinamine was developed. Signal enhancements were obtained by heavy atom effect, use of surfactant agent and use of basic medium. Alternatively, an ultraviolet treatment of the analyte was tried in order to induce a phoshor with higher phosphorescence quantum efficiency. A limit of detection of 2.70 ng and linear dynamic range of 2 orders of magnitude were achieved in paper substrate treated for background reduction. A study was performed to verify potential interferences of several pharmacological active ingredients that could be associated with rescinamine in a pharmaceutical preparation. The method was tested by analyzing rescinamine in three different laboratory-made tablets.