Separation of niobium(V) and tantalum(V) by capillary electrophoresis withchemiluminescence detection

A new method for simultaneous determination of niobium(V) and tantalum(V) i s described. Capillary electrophoresis (CE) with chemiluminescence (CL) det ection was used in the separation and detection of niobium(V) and tantalum( V) which catalyze the CL reaction of luminol with hydrogen peroxide (H2O2). The mixing mode used in this work allowed the CL reagents (luminol and H2O 2) and the analytes to meet simultaneously at the detection window while in conventional ion chromatography chemiluminescence (ICCL) the CL reagents a re mixed in advance. Therefore, in this work the luminol as a component of the separation carrier electrolyte avoided the loss of light signal which o ccurs when luminol and hydrogen peroxide are mixed in advance in ICCL. Sign al enhancement was achieved by sample stacking injection in the electrophor esis process. A sample volume of 20 nl was injected. The metal ions were se parated in less than 7 min with sodium dihydrogen phosphate buffer (pH 2.5, 10 mmol/l). The detection limits of this method for niobium(V) and tantalu m(V) (S/N = 3) are 826 zmol (4.13 x 10(-10) mol/l) and 640 amol (3.2 x 10(- 8) mol/l), respectively. The sensitivity of the metal ions was satisfactory . (C) 2001 Elsevier Science B.V. All rights reserved.