Quantitative Analysis of Non-UV-Absorbing Cations in Soil Samples by High-Performance Capillary Electrophoresis. An Experiment for Undergraduate Instrumental Analysis Laboratory

Cations such as Ca2+, Mg2+, K+, NH4+, Na+, Mn2+, and Zn2+ are very important in soil even though some of them are present in low concentrations. Plants, to grow well, must be planted in soil with cations in sufficient quantities and proper ratios. The number of cations and the variability of their concentrations in soils may make soil too complex for quantitative analysis by traditional methods. We describe a high-performance capillary electrophoresis (HPCE) experiment for quantitative analysis of cations in soil samples. The method is economical and fast, and is potentially applicable to normal soil analysis. Since HPCE is a useful and modern technique, it is necessary that undergraduate students in chemistry learn to use it. This experiment is designed as a one- or two-week laboratory experiment in Instrumental Analysis. It has been performed in the laboratory at Truman State University for two years, and students have obtained excellent results.