Effects of Micelles and Vesicles on the Oximolysis of p-Nitrophenyl Diphenyl Phosphate: A Model System for Surfactant-Based Skin-defensive Formulations against Organophosphates

The rates of oximolysis of p-nitrophenyl diphenyl phosphate (PNPDPP) by Acetophenoxime; 10-phenyl-10-hydi-oxyiminodecanoic acid; 4-(9-carboxynonanyl)-1-(9-carboxy-1-hydroyiminononanyl) benzene; 1-dodecyl-2-[(hydroxyimino)methyl]-pyridinium chloride (IV) and N-methylpyridinium-2-aldoxime chloride were determined in micelles of N-hexadecyl-N,N,N-trimethylammonium chloride (CTAC), N-hexadecyl-N,N-dimethylammonium propanesulfonate and dioctadecyldimethylammonium chloride (DODAC) vesicles. The effects of CTAC micelles and DODAC vesicles on the rates of oxymolysis of O,O-Diethyl O-(4-nitrophenyl) phosphate (paraoxon) by oxime IV were also determined. Analysis of micellar and vesicular effects on oximolysis of PNPDPP, using pseudophase or pseudophase with explicit consideration of ion exchange models, required the determination of the aggregate`s effects on the pK(a), of oximes and on the rates of PNPDPP hydrolysis. All aggregates increased the rate of oximolysis of PNPDPP and the results were analyzed quantitatively. In particular, DODAC vesicles catalyzed the reaction and increased the rate of oximolysis of PNPDPP by IV several million fold at pH`s compatible with pharmaceutical formulations. The rate increase produced by DODAC vesicles on the rate of oximolysis paraoxon by IV demonstrates the pharmaceutical potential of this system, since the substrate is used as an agricultural defensive agent and the surfactant is extensively employed in cosmetic formulations. (C) 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:1040-1052, 2009

Development of a heavy metal sorption system through the P=S functionalization of coconut (Cocos nucifera) fibers

Lignocellulosic residues are interesting materials for the production of heavy metal adsorbents for aquatic systems. Whole fibers taken from coconut (Cocos nucifera) husks were functionalized with the thiophosphoryl (P=S) group by means of the direct reaction with CI(3)P=S, (CH(3)O)(2)CIP=S or (CH(3)CH(2)O)(2)CIP=S in order to obtain an adsorptive system for `soft` metal ions, particularly Cd(2+). These functionalized fibers (FFs) were characterized by means of elemental analysis, infrared spectroscopy, thermal analysis and acid-base titration. Adsorption isotherms for Cd(2+) fitted the Langmuir model, with binding capacities of 0.2-5 mmol g(-1) of FF at 25 degrees C. (C) 2009 Elsevier Ltd. All rights reserved.