Abstract
In the present study a pressure-assisted MEEKC method with reversed-polarity using a conventional CE instrument with UV detection and uncoated fused silica capillaries is validated as a high-throughput methodology for the lipophilicity determination of the neutral species of acidic compounds (pK<sub>a</sub> &gt; 3.5). After the calibration of the system with four standard compounds of known log P<sub>o/w</sub>, mass distribution ratios (log k<sub>MEEKC</sub>) of new molecules can be directly converted into log P<sub>o/w</sub> values by means of a simple linear equation (log P<sub>o/w</sub>=a·log k<sub>MEEKC</sub>+b). The method was internally and externally validated for a log P<sub>o/w</sub> range between -1.54 and 4.75, with higher accuracies than conventional liquid chromatographic methods.
Highlights
microemulsion electrokinetic chromatography (MEEKC) as high-throughput surrogate model for the determination of lipophilicityAccording to IUPAC [1], lipophilicity represents the affinity of a molecule or a moiety for a lipophilic environment that is commonly measured by its distribution behavior in a biphasic system
It can only be applied to neutral species, the broad pH range of application allows, in most cases, the finding of experimental conditions which ensure the analyte is in its neutral form. This is clearly an advantage over conventional chromatographic methods, since column stability might be a critical factor at such extreme pH values. This is maybe the most significant advantage over traditional chromatographic methods, MEEKC measurements can be accurately correlated with log Po/w without the need of molecular descriptors since ME are better surrogates of n-octanol/water systems than C18 stationary phases
The ability of the model to reproduce the data included in the set of compounds is measured by the determination coefficient of the model (R2), which in our case estimates the proportion of the variation in the predicted log Po/w that can be explained according to the model
Summary
MEEKC as high-throughput surrogate model for the determination of lipophilicityAccording to IUPAC [1], lipophilicity represents the affinity of a molecule or a moiety for a lipophilic environment that is commonly measured by its distribution behavior in a biphasic system. This is maybe the most significant advantage over traditional chromatographic methods, MEEKC measurements can be accurately correlated with log Po/w without the need of molecular descriptors since ME are better surrogates of n-octanol/water systems than C18 stationary phases. In a previous study involving buffers over a wide range of pH values [14], we proposed a seminal pressure-assisted method with reversed polarity allowing measurements to be made at pH 2 and using conventional uncoated fused silica capillaries, which are much less expensive than the sulfonic acid coated capillaries.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
