Cations in soil solution and drainage water are traditionally determined by Atomic Absorption Spectrophotometry (AAS) (Ca2+ and Mg2+) and Atomic Emission Spectrophotometry (AES) (K+ and Na+). Ion chromatography is a technique that permits simultaneous determinations of Li+ Na+. NH4+, K" Mg2+ C2+, Sr2+ and Ba2+ in water. The objective of this paper is 10 study a single column ionic chromatography (SCIC) as a method for the determination of major cations in soil solution and drainage water. A column packed with silica base coated with polybutadiene/maleic acid copolymer and a mobile phase consisting of a 0.1 mM EDTA acid I 3.0 mM HNO, mixture were used. Conductivity detector was placed after the separation column. The system with a flow rate of 1 ml·min-1 allows the detection of Na+ NH4+,. K+ Mg2+", Ca2+ in less than 20 minutes. Using a 100 ul sample loop the SCIC detection limits were 40 ppb for Na+. 20 ppb for NH4+, 60 ppb for K+ 50 ppb for Mg2+ and 85 ppb for Ca2+. results were highly reproducible in a wide range of concentration (C.V. 0.77-6.27% at concentrations higher than 0.5 ppm and 0.97-15% at lower concentrations) Results for Na+ K+ Mg2+ and Ca2+ obtained by the SCIC method were compared with those obtained by EAS and AAS being statistically no different at P<0.05 level (t-test). The SCIC method allows simultaneuos determinations of major cations in soil solution and drainage water with proved reproducibility. Futhermore. the SCIC teehnique is rapid and requires small sample volumes (maximum 100 ul) for the analysis of main cations in soil solution and drainage water.

Ponencia presentada en el 8th Symposium of Handling of Environmental and Biological Samples in Chromatography and and the 26th Scientific Meeting of the Spanish Group of Chromatograph. Celebrado del 26 al 29 de octubre, 1997, en Almería.

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