title: Silver nanoparticles enhanced luminescence of terbium complex in solution for L-dopa determination.
abstract: Luminescent properties of a terbium (Tb3+)-L-3, 4-dihydroxyphenylalanine (L-dopa) complex by binding to colloidal silver nanoparticles (Ag NPs) have been presented. Luminescence intensity of the L-dopa complex was dramatically enhanced about 6-7 times by introducing Ag NPs. The Ag NPs concentration on the luminescent intensity was regarded as a main factor that balancing between an enhancing and a quenching effect of the Ag NPs. It was observed that changing the concentration of L-dopa causes the change in luminescence intensity. Under the optimized condition, the luminescence intensity of the system was linearly related to the concentration of L-dopa. Based on this observation, L-dopa-Tb3+ complex containing Ag NPs has been applied for the determination of L-dopa in pharmaceutical formulation. Linear responses of luminescence intensity were observed in the concentration range of 0.25 to 1.5 nM (r = 0.9934) of L-dopa with limit of detection 0.042 nM. The performance of the system was tested using 1.0 x 10(-9) M of L-dopa, yielding a precision of 1.21% RSD for nine replicate measurements. The present method has been successfully applied to determine L-dopa in pharmaceutical samples.
authors.affiliation: Department of Chemistry, Kyungpook National University, Daegu, 702-701, South Korea.
authors.forename: Al-Mahmnur
authors.initials: AM
authors.lastname: Alam
authors.forename: Mohammad
authors.initials: M
authors.lastname: Kamruzaman
authors.forename: Sang Hak
authors.initials: SH
authors.lastname: Lee
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
authors.forename: Hae Jin
authors.initials: HJ
authors.lastname: Jo
authors.forename: Yeoun Suk
authors.initials: YS
authors.lastname: Suh
authors.forename: Sung Hong
authors.initials: SH
authors.lastname: Kim