Determination of trace silver by solid substrate-room temperature phosphorescence quenching method based on double catalytic system of meta-nitrophenyfluorone-polyoxyethylene-chromium-potassium bromate-beta-cyclodextrin.
A new solid substrate-room temperature phosphorescence (SS-RTP) quenching method for the determination of trace silver has been established. It is based on the fact that when using Mg(2+) as ion perturber and beta-CD as surfactant, the system of meta-nitrophenyfluorone (R)-polyoxyethylene-Cr(III) can emit strong and stable room temperature phosphorescence signal on filter paper whose surface is modified by polyvinyl alcohol (PVA)-H(3)BO(3)-NaOH. Ag(I) can catalyze KBrO(3) oxidizing R-PEO-Cr(III) system which causes the quenching of SS-RTP. The reducing value of phosphorescence intensity (DeltaI(p)) is directly proportional to the concentration of Ag(I) in the range of 3.2-160 ag spot(-1) (corresponding concentration: 2.43 fg ml(-1), the sample volume: 0.40 microl spot(-1)) with a detection limit (LD) of 0.97 ag spot(-1). The regression equation of working curve can be expressed as DeltaI(p)=13.92+0.3089m(Ag)+ (ag spot(-1)) (r=0.9983, n=6). This method has many advantages, such as a wide linear dynamic range, high sensitivity, good repeatability and selectivity. It has been applied to the determination of trace silver in real samples with satisfactory results. What is more, the mechanism of SS-RTP quenching method based on Ag(I) catalyzing KBrO(3) oxidizing meta-nitrophenyfluorone has also been discussed.