EXTRACTION AND COLORIMETRIC DETERMINATION OF PICLORAM IN SOIL

A colorimetric method has been developed for estimation of picloram (4-amino-3,5,6-trichloropicolinic acid) in the soil. It involves diazotization of picloram with nitrite in sulfuric acid solution. The color developed is stable in the absence of ultraviolet radiation without a coupling agent; the reaction is specific and not subject to interference from substances commonly present in the soil. Picloram can be quantitatively extracted from most soils by 1N NH4OAc, 2N KCl, or a KCl-KOH solution. This method is simple, rapid, and suitable for use in analyzing a large number of samples. It is not sensitive enough for determination of trace quantities of picloram (<0.5 p.p.m.). © 1969, American Chemical Society. All rights reserved.