USE OF AMMONIUM OR POTASSIUM DIHYDROGEN PHOSPHATE TO PROTECT PESTICIDES IN SPRAY MIXTURES PREPARED WITH ALKALINE WATERS

A practical procedure was developed to reduce the possibility of alkaline hydrolysis of pesticides in spray tanks when naturally alkaline waters are used. Natural alkaline water samples collected from the Holland Marsh area and Niagara Region in Ontario had pH values in the range of 7.60-9.68, and their buffer capacity ranged from 0.21 X 10-2 M to 2.00 X 10-3 M. Adding 0.5 g of NH4H2PO4 or KH2PO4 per liter of water lowered the pH of all samples tested to 6.7 ± 0.3. The majority of pesticides are most stable at this pH and the probability of alkaline hydrolysis occurring can be reduced by this simple procedure. © 1979, American Chemical Society. All rights reserved.