Solid substrate-room temperature phosphorescence method for the determination of trace Mn(II) based on oxidizing reaction of hydrogen peroxide using alpha,alpha'-bipyridine as sensitizer.

A new solid substrate-room temperature phosphorescence (SS-RTP) method for the determination of trace manganese (II) has been established. It bases on the fact that fullerol (R) emits strong and stable room temperature phosphorescence (RTP) on filter paper substrate. H2O2 can oxidize R to cause the SS-RTP quenching. But manganese (II) can obstruct H2O2 to oxidize R, and enhance the RTP of R. alpha,alpha'-Bipyridine (Bipy) can sensitize the RTP. After adding Bipy, the DeltaI(p) enhances 7 times than that without Bipy. Under the optimum conditions, the linear dynamic range of this method is 0.016-1.12 pg spot(-1) with a detection limit (L.D.) of 4.6 fg spot(-1) (m(Mn(2+) is the absolute mass of Mn(2+)), and the regression equation of working curve is DeltaI(p)=25.20 + 63.55 m(Mn(2+) (pg spot(-1)), n=6, r=0.9983. For 0.016 and 1.12 pg spot(-1) Mn(2+), RSDS are 4.3 and 4.8%, respectively (n=7). This method has been applied to the determination of trace manganese (II) in actual sample with high sensitivity and good selection. And the reaction mechanism of SS-RTP is discussed.

Determination of trace selenium by solid substrate-room temperature phosphorescence enhancing method based on potassium chlorate oxidizing phenyl hydrazine-1,2-dihydroxynaphthalene-3,6-disulfonic acid system.

A new method for the determination of trace selenium based on solid substrate-room temperature phosphorimetry (SS-RTP) has been established. This method was based on the fact that in HCl-KCl buffer solution, potassium chlorate could oxidize phenyl hydrazine to form chloridize diazo-ion after being heated at 100 degrees C for 20 min, and then the diazo-ion reacted with 1,2-dihydroxynaphthalene-3,6-disulfonic acid to form red azo-compound which could emit strong room temperature phosphorescence (RTP) signal on filter paper. Selenium could catalyze potassium chlorate oxidizing the reaction between phenyl hydrazine and 1,2-dihydroxynaphthalene-3,6-disulfonic acid, which caused the sharp enhancement of SS-RTP. Under the optimum condition, the relationship between the phosphorescence emission intensity (DeltaIp) and the content of selenium obeyed Beer's law when the concentration of selenium is within the range of 1.60-320 fg spot-1 (or 0.0040-0.80 ng ml-1 with a sample volume of 0.4 microl). The regression equation of working curve can be expressed as DeltaIp=13.12+0.4839CSe(IV) (fg spot-1) (n=6), with correlation coefficient r=0.9991 and a detection limit of 0.28 fg spot-1 (corresponding to a concentration range of 7.0x10(-13) g ml-1 Se(IV), n=11). After 11-fold measurement, R.S.D. were 2.8 and 3.5% for the samples containing 0.0040 and 0.80 ng ml-1 of Se(IV), respectively. This accurate and sensitive method with good repeatability has been successfully applied to the determination of trace selenium in Chinese wolfberry and egg yolk with satisfactory results. The mechanism of the enhancement of phosphorescence was also discussed.