ONLINE SAMPLE PRETREATMENT AND DETERMINATION OF LANTHANIDES IN COMPLEX MATRICES BY CHELATION ION CHROMATOGRAPHY

The rapid determination of lanthanides in complex matrices has been de veloped by an on-line sample pretreatment of chelation ion chromatogra phy. In the present system, selective chelating resin and sulfonated c ation exchanger concentrated lanthanides while eliminating bull. quant ities of alkali, alkaline earth and transition metals from sample matr ices. The concentrated lanthanides which were separated on a mixed-bed ion exchange column were eluted by a concentration gradient of oxalic acid (Ox) and diglycolic acid (DGA), coupled with postcolumn spectrop hotometric detection with 4-(2-pyridylazo) resorcinol (PAR) at 520 nm. The overall analysis time after sample digestion was less than 55 min . The method detection limits (signal-to-noise ratio 3:1) from heavy l anthanides to light lanthanides were in the range of 0.6-5.5 ng mL(-1) and the R.S.Ds were within 1.8%-5.5%. This method was applied to soil , ore, nodular cast iron, plant, grain, and rare-earth fertilizer samp les. The results of those real sample analyses were satisfactory.