TIME-RESOLVED LUMINESCENCE AS A NOVEL DETECTION MODE FOR THE SIMULTANEOUS HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC DETERMINATION OF GADOLINIUM-DOTA AND GD3+

摘要

The simultaneous determination in aqueous media of the gadolinium ion (Gd3+) and the macrocyclic chelate Gd-DOTA (DOTA = 1, 4, 7, 10-tetraazacyclododecane-1, 1, 4, 7, 10-tetraacetic acid) used in magnetic resonance imaging (MRI) is described, The proposed approach combines a reversed-phase high-performance liquid chromatographic (RP-HPLC) separation and time-resolved luminescence detection (TRL). The spectroscopic properties of Gd-DOTA and various other Gd chelates (Gd-CDTA, Gd-TETA, Gd-EDTA, Gd-DTPA and Gd-TTHA) (CDTA = cyclohexanediaminetetraacetic acid; TETA = 1, 4, 8, 11-tetraazacyclotetradecane-1, 4, 8, 11-tetraacetic acid; EDTA = ethylenediaminetetraacetic acid; DTPA = diethylenetriaminepentaacetic acid; TTHA = triethylenetetraaminehexaacetic acid) were established in order to optimize TRL detection (lambda(exc) = 274 nm, lambda(em) = 313 nm, delay time 0.1 ms, gate time 10 ms), The Gd3+ ion possibly present in the matrix was detected as a Gd-CDTA chelate after dilution of the sample by a pH 7.6-buffered 1 x 10(-2) M aqueous CDTA solution, Then, Gd-DOTA and Gd3+ ion (as Gd-CDTA chelate) were chromatographed on an RP C-8 HPLC column, The eluent consisted of pH 7.6 TRIS-HCl buffer + acetonitrile (98 + 2 v/v), The analytical figures of merit obtained for Gd-DOTA in aqueous solution were as follows: linearity was assumed from 10 to 5000 mu mol l(-1); the limit of detection (LOD, S/N = 3) was 21 mu mol l(-1), which corresponds to 235 ng of Gd-DOTA injected, The repeatability (RSD = 10%, n = 15) and the intra-assay reproducibility(RSD = 12%, n = 6) were studied for a 50 mu mol l(-1) solution, With this method, 130 ng of Gd3+ ion (as Gd-CDTA) injected can be detected, which corresponds to an LOD of 42 mu mol l(-1), The LOQ fur Gd3+ ion was 140 mu mol l(-1). Consequently, Gd3+ ion can be distinguished from chelated Gd-DOTA in aqueous solution (at the 0.2% level). [References: 23]