The Horsetail Herb and Bioassays

One interesting use for horsetail derives from its affinity for gold in liquid solution. Since horsetail concentrates gold more than most other plants, it has been used in bioassays for the metal. 



A bioassay is a procedure for determining the concentration, purity, and/or biological activity of a substance (e.g., vitamin, hormone, plant growth factor, antibiotic, enzyme) by measuring its effect on an organism, tissue, cell, enzyme or receptor preparation compared to a standard preparation. 


For a more detailed explanation about bioassays, here is a link:


Bioassay - Wikipedia.org Definition