On-line sample pretreatment and determination of lanthanides in complex matrices by chelation ion chromatography

The rapid determination of lanthanides in complex matrices has been developed by an on-line sample pretreatment of chelation ion chromatography. In the present system, selective chelating resin and sulfonated cation exchanger concentrated lanthanides while eliminating bull. quantities of alkali, alkaline earth and transition metals from sample matrices. 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 spectrophotometric 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 lanthanides 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 samples. The results of those real sample analyses were satisfactory.