• Addison, J.B.
  New Brunswick Research and Productivity Council
  
• Silk, P.J.
  New Brunswick Research and Productivity Council
  
• Wiesner, C.J.
  New Brunswick Research and Productivity Council
  
• Henderson, G.W.
  New Brunswick Research and Productivity Council
  

Vapour pressures of fenitrothion and aminocarb over a temperature range of 20-40°C have been determined using a dynamic gas saturation method. Polyurethane foam vapour traps were used for volatilzed materials from sand and glass surfaces and Porapak Q was used as a trapping medium for materials volatilized from foliage surfaces. The vapour pressures (VP's) were linearly related to the reciprocal temperature by the equations:

log10(VP) = 6.3362 - 3197.8/T for fenitrothion

where T = °K and VP = Torr. The equation was established from the data by linear regression analysis with a correlation coefficient (r) of 0.955 and a heat of vaporization ( ∆Hvap) = 14.7 Kcals/mole. For aminocarb, the following equation was obtained: 

log10(VP) = 8.8316 - 4021.4/T

with a correlation coefficient of 0.965 and a ∆Hvap = 18.4 Kcals/mole.

The greatest vapour loss rates were from sand incorporated with insecticide followed by vapour loss rates from glass surfaces. The lowest vapour loss rates were from foliage surfaces. Water vapour appears to play a considerable role in attenuating evaporation rates from these surfaces.