Determination of Lysine by Ag@SiO2 Nanoparticles Enhanced Room Temperature Phosphorescence of Fluorescein Isothiocyanate on Filter Paper Substrate

Metal enhanced room temperature phosphorescence(MERTP) of fluorescein isothiocyanate isomer I(FITC) was observed with the presence of proper content of Ag@SiO2 core-shell(Ag@SiO2).The FITC-MERTP was quenched by the existing of lysine in the system.Based on this phenomenon,a novel method for determination of lysine had hereby been developed.Under the added amount ratio of FITC to Ag@SiO2 of 1∶1.5,pH of 8.0,the detection limit for lysine was 0.270 μmol/L,the response was linearly proportional to the concentration of lysine in the range of 1.50-90.5 μmol/L,the recoveries of standard addition of artificial samples were in the range of 97.0%-108.0%,the relative standard deviation was less than 2.1%(n=9).A satisfactory result was obtained when the established method applied to the determination of lysine in compound lysine hydrochloride and zinc gluconate granules and lysine hydrochloride and calcium hydrogen phosphate tablets