Sensitive method for the spectrophotometric determination of boron in plants and waters using crystal violet

Abstract

A sensitive and rapid spectrophotometric method for the determination of boron is described, which is based on the formation of a blue complex at pH 1–2 between the anionic complex of boric acid with 2,6-dihydroxybenzoic acid and crystal violet; the colour is stabilised with poly(vinyl alcohol). At 600 nm the calibration graph is linear in the range 0.3–4.5 µg of boron per 25 ml of final solution with a relative standard deviation of ±2.6% for 0.069 µg ml^–1 of boron. The molar absorptivity is 3.75 × 10⁴ l mol^–1 cm^–1. The method has been applied to the determination of boron in plants and natural waters.