The enantiomeric separation of some poorly water-soluble organophosphorus pesticides (OPs) has been investigated using nonaqueous solvent and aqueous-organic solvent systems. In this work, sodium cholate (SC) either with SDS or gamma-CD was used to achieve enantiomeric separations of four neutral and poorly water-soluble OPs, i.e., profenofos, prothiofos, sulprofos, and pyraclofos. Electrophoretic medium consisted of a mixture of methanol (MeOH) with ACN (4:1 v/v) or a mixture of MeOH with H(2)O and ACN (5:4:1 v/v/v). On one hand, NACE was applied for enantiomeric separation of pyraclofos using a large amount of chiral and achiral surfactants (SC and SDS). On the other hand, H(2)O was added to act as a solvent additive to increase the solubility of gamma-CD in the organic solvents such as MeOH and ACN, in which the solubility of gamma-CD was very low. The presence of H(2)O was found to be particularly useful for the enantiomeric separation of profenofos, prothiofos, and sulprofos. In this way, the range of application of the neutral CDs in CE has been extended. In addition, SC was used as the only electrolyte. The proposed method has been applied for the analysis of soil samples.

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A high-performance CE with amperometric detection (CE-AD) was employed for the kinetic study of keto-enol tautomerism of p-hydroxyphenylpyruvic acid (pHPP). Several factors (concentration of b-cyclodextrin (b-CD), concentration and pH of running buffer, separation voltage and injection time) affecting CE-AD were investigated and separation conditions were optimized. The kinetics of pHPP was performed in water solution and phosphate solution under different pH and temperature, the homologous ketonization rate constants and half-life were obtained. Also, the activation energy was calculated according to the rate constants under different temperature. The experimental results indicated that b-CD played an important role in the separation, therefore UV spectrometric method was applied for the study of complexation interaction between ketonic pHPP and b-CD. The results indicated that the stoichiometric ratio of the pHPP-b-CD complex was 1:1 and formation constant was determined. The obtained kinetic results are in correspondence with those reported by our group with CE-UV.