Mingelgrin, U., Division of Soil Residues Chemistry, Institute of Soils and Water, Agricultural Research Organization, Volcani Center, PO Box 6, Bet Dagan, Israel
Kljger, L., Division of Soil Residues Chemistry, Institute of Soils and Water, Agricultural Research Organization, Volcani Center, PO Box 6, Bet Dagan, Israel
Saltzman, S., Division of Soil Residues Chemistry, Institute of Soils and Water, Agricultural Research Organization, Volcani Center, PO Box 6, Bet Dagan, Israel

A procedure which enables the identification of the hydrolysis products of a number of phosphoric and phosphorothioic esters was developed. This procedure, which includes thin‐layer chromatography (t.l.c.), gas chromatography and u.v. spectroscopy, has been used to demonstrate that surface hydrolysis on kaolinite is a general property of bioactive phosphoric and phosphorothioic esters. The path of hydrolysis was shown to be the breakage of the PO A or PSA bond, where A is the electron attracting moiety of the organic molecule. Copyright © 1979 John Wiley & Sons, Ltd