Application of the calcium-calcichrome colour reaction to the spectrophotometric determination of calcium in plant material

A highly selective spectrophotometric method has been developed for the determination of micro-amounts of calcium in plant material with calcichrome as the colour reagent. The absorption maximum of the complex is at 520 nm. At this wavelength, Beer's law is obeyed in the range of 0–50 μg Ca2+/10 ml. The molar absorptivity of the system is 6,6×103 1 mol−1cm−1. The ions normally present in plant material do not interfere when tri-ethanolamine is added. Plant material from several sources has been analysed by this method and the results have been found to be satisfactory.