The determination of hydrothol 191 (amine salt of endothall) in eutrophic wastewater ponds

The use of the amine salt of endothall (Hydrothal 191) to control algae contributing to total suspended solids in wastewater treatment lagoons required a simple, sensitive and accurate analytical method to meet regulators' requirements for discharge. Aqueous environmental samples containing endothall were adsorbed on an anion solid phase extraction (SPE) column, eluted with phosphoric acid, derivatized with 2,3,5,6-heptafluoro-p-tolyhydrazine, partitioned into methyl-t-butyl ether and analyzed by gas chromatography/electron capture detection. Limits of detection (LOD) and quantification (LOQ) were 0.05 ppm and 0.17 ppm, respectively. The method's sensitivity, precision and accuracy make it useful for regulatory purposes and environmental research.