Simplified Analysis for Soil Samples with Compact Water Quality Meter <LAQUAtwin> – Measurement of exchangeable calcium ion and potassium ion in soil –

By: Keiko KUWAMOTO

24 November 2013


Exchangeable calcium ion (Ca2+) and potassium ion (K+) extracted with 1 mol/L ammonium acetate (NH4OAc) solution were measured with Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Simple and quick measurements by AAS or ICPOES are difficult in the field because these are large analytical instruments. A simplified analysis was tried with the compact water quality meter <LAQUAtwin> (Ion Selective Electrode; ISE). In case of measurement of Ca2+ and K+ with ISE methods, the high NH4OAc concentration solution produced inaccurate results due to a potential difference shift. In this report, LAQUAtwin meters are used for soil sample measurements. The procedure used herein proves that Ca2+ and K+ are easily measurable using this procedure with the ISE methodology.

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