The relationship between surface adsorption and the hydrolysis of amitraz in anionic surfactant solutions.
The adsorption of amitraz to various adsorbents was studied in terms of the amount and rate of adsorption and the effect that adsorption had on the stability of amitraz in an aqueous environment. Adsorption results showed that in terms of their ability to adsorb amitraz from solution the adsorbents tested in this study can be ordered as follows: coarse carbon > cation exchange resin > or = anion exchange resin > fine carbon. Amitraz was not adsorbed on sand and potassium oxihumate. Adding sodium lauryl sulfate and potassium oxihumate to aqueous suspensions of suspended adsorbents containing adsorbed amitraz showed that both these anionic surfactants significantly increased the hydrolysis rate because the half-lives for amitraz was reduced from 27 days for a suspension to only 8 hours for amitraz adsorbed to a cation exchange resin and suspended in an aqueous buffer pH 5.8 containing 0.5% of the anionic surfactant sodium lauryl sulfate and 12 hours when 1% potassium oxihumate was added.
de Villiers
Melgardt M
MM
Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe, Louisiana, USA. devilliers@ulm.edu
van Eeden
Charmaine M
CM
Malan
Sarel F
SF
Devarakonda
Bharathi
B
Liebenberg
Wilna
W
Kolling
William M
WM
D000327:Adsorption; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D006868:Hydrolysis; D007306:Insecticides / Q000737:chemistry*; D007700:Kinetics; D013501:Surface-Active Agents / Q000737:chemistry*; D014052:Toluidines / Q000737:chemistry*
D007306:Insecticides; D013501:Surface-Active Agents; D014052:Toluidines; C014983:amitraz