Effect of Temperature on free acidity, Ph, Viscosity, Wettablity and emulsion stability of emulsifiable concentrates and wettable powders formulations

Information on the physical and chemical characteristics of a product; which are necessary to characterize a pesticide compliance with std specifications, is directly used in hazard assessment to provide evidence on how the quality of a product varies with time under the influence of environmental factors such as temperature, humidity and light. The study aimed to investigate the possibility of occurrence of changes in the values of some physical parameters of emulsifiable concentrates and wettable powders as results of temperature change (20, 25, 30 ... 50 deg C). Insecticides tested were deltamethrin, carbaryl, and chlorpyrifos, each in form of three generics from different companies. Methods used were those of CIPAC. It was found that wettability of the three generics of deltamethrin WP did not show a specific trend with increase in temperature, the different chemicals wetting times differed significantly and behaved differently. The three generics of carbaryl WPs showed significant increases in their wetting times. In all cases, increasing the temperature resulted in decreasing the viscosity. The three generics of chlorpyrifos when measured at lower temperatures showed the same pH range. At 35 deg C and above, all generics pH values differed from each other. For the WPs, the pH values decreased as the temperature increased. The three chlorpyrifos ECs did not showed similar acidity even at 20DC. The three ECs of deltamethrin were drastically affected by changing the test temperature to 35 deg C. The deltamethrin WPs at lower temperatures showed the same free acidity values. The three WPs of carbaryl at lower temperatures showed different free acidity values. At 0 times in Emulsion Stability, most of tested groups were not affected by the test temperature. Except Chloroguard® at temperatures up to 35 deg C and Decis®25EC. At 0.5h, five of these ECs showed cream layer at the different test temperatures. The readings at 2h also showed the appearance of the cream layer, except in Decis®l00. After 24h the readings differed between insecticides. The reemulsification test (24.5h) in most cases showed cream layers. Very few cases resulted in no cream. It is concluded that the properties of free acidity, pH range viscosity, wettability and Emulsion Stability, have considerably changed with temperature. It is recommended that there is a possibility of measuring the properties under laboratory temperature stating the temperature at the time of the measurement