Determination of sulfate‐sulfur in plant tissue by inductively coupled plasma spectrometry

A method is described to accurately assess inorganic sulfur concentration in plant tissue by ICP spectrometry using a weak anion exchange resin. The procedure is faster and capable of much higher precision than standard gravimetric analysis. The method was tested using four plant tissues: sugar beet, alfalfa, tomato and prune; which were extracted for sulfate‐sulfur (SO4‐S) with two percent acetic acid. Extracts were passed over a weak anion exchange resin where SO4‐S is bound. The column was washed with 0.1N HCl to remove non‐SO4‐S compounds, SO4‐S was eluted with 1.0N HCl and determined by ICP Spectrometry. Sulfate‐sulfur recovery was assessed using both inorganic and organic sulfur spiking and comparison with gravimetric analysis. Results conclusively show that this procedure effectively isolates SO4‐S on four plant materials ranging from 250–6000 ug/gm SO4‐S. There is minimal recovery from organic sources associated with the extract.