530 EXTRACTABLE SULFATE-SULFUR IN BOTANICAL MATERIALS
SO4-S
Total extractable sulfate by 2% acetic acid extraction. Pre-concentration and isolation on anion exchange resin and quantitative measurement by atomic emission spectroscopy (ICP-AES).
Summary: This method quantitatively determines the amount of sulfate-sulfur (SO4-S) in botanical materials by extraction with a solution of 2 % acetic acid. Sulfate contained within the extract is bound to an anion exchange resin, organo-sulfur compounds are removed by washing with 0.1N HCl, and sulfate is eluted with 1.0N HCl. The sulfur content of the extract is determined by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The method may be semi-quantitative on some botanical materials which have a high anion exchange capacity or in samples where sulfate is not the most significant anionic form of sulfur. The method has a detection limit of 10 ppm. The analysis requires approximately 0.15 g of sample material but 5 g is requested to allow for quality control samples.