a novel and highly sensitive catalytic method for the determination of ultra trace amounts of cerium with spectrophotometric detection

cerium (iv) has a catalytic effect on the very slow redox reaction between gallocyanine and bromate in acidic media. the reaction was monitored spectrophotometrically at 525 nm by a fixed time method of 4.0 rnin from initiation of the reaction. the decrease in absorbance at 525 nm is proportional to the ce (iv) concentration in the range of 0.005-1.000 and 1.00-10.00 pg. ml-l. the limit of detection is 2.0 ng.ml-'. the relative standard deviation for ten replicate analyses of 0.100 pg.ml-' is 1.5%. the method is used for the determination of cerium in synthetic and in real samples, with good accuracy. the effect of interfering cations and anions was also studied.