FLOW PROCEDURE FOR ION-EXCHANGE PRECONCENTRATION AND ONLINE SPECTROPHOTOMETRIC DETERMINATION OF IRON(III) AS ITS THIOCYANATE COMPLEX

On-line ion-exchange preconcentration of iron(III) on a conventional c ation exchange resin with spectrophotometric detection based on thiocy anate complexation is described. The calibration graph is linear over the range 0.01-0.2 mu g ml(-1) and the detection limit (3 sigma) is 6 ng ml(-1) for a 6-ml sample. No interference effects were detected. Th e recovery of iron from the resin is 95%. 12 samples h(-1) can be anal ysed.