1-Octanol/Water Partition Coefficient (K ow ) and pK a for Ionisable Pesticides Measured by apH-Metric Method
✍ Scribed by Chamberlain, Keith; Evans, Avis A.; Bromilow, Richard H.
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 659 KB
- Volume
- 47
- Category
- Article
- ISSN
- 1526-498X
No coin nor oath required. For personal study only.
✦ Synopsis
pK, values for a wide range of commonly used ionisable pesticides, together with the log KO, values of the most lipophilic form of each, have been measured using pH-metric techniques. Examples of acids, bases and multiprotic compounds from the major classes of herbicides, and a number of insecticides and fungicides that contain ionisable groups, are included. The pK, and log KO, values so obtained were generally in good agreement with values taken from the literature that were measured by other methods.
The lower limit of log KO, that could be measured by the pH-metric method lay below the -0.97 obtained for amitrole, but the method could not be applied to glyphosate for which shake-flask measurements indicated log KO, below -3. The highest log KO, obtained in this study was 5.12 for pentachlorophenol.
The pH-metric technique offers a rapid and convenient method to determine pK, and log KO, for ionisable compounds, especially when utilising an automatic titration system linked to a dedicated computer.