Inductively coupled plasma optical emission spectrometric determination of gadolinium in urine using flow injection on-line sorption preconcentration in a knotted reactor

An on-line gadolinium preconcentration and determination system, implemented with ultrasonic nebulization coupled to inductively coupled plasma optical emission spectrometry (ICP-OES), associated with flow injection (FI) was studied. Gadolinium was retained as Gd-2-(5-bromo-2-pyridilazo)-5-diethylaminophenol complex (Gd-5-Br-PADAP) at pH 9.0, on the inner walls of the knotted reactor (KR). The collected analyte complexes were quantitatively eluted from the 200 cm KR with 30% (v/v) nitric acid. An enhancement factor of 255-fold was obtained ( 17 for KR and 15 for USN). The detection limit ( DL) value for the preconcentration of 15mL of sample was 4.0 ng L-1. The relative standard deviation (RSD) was 3.5%, calculated from the peak heights obtained. The calibration graph using the preconcentration system for gadolinium was linear, with a correlation coefficient of 0.9996 at levels near the detection limit up to at least 200 mg L-1. The method was successfully applied to the determination of gadolinium in urine samples.