title: Direct determination of the enantiomeric purity or enantiomeric composition of methylpropionates using a single capacitive microsensor.
abstract: Capacitive enantioselective sensors have been demonstrated to provide antipodal signals upon dosage of, e.g., the enantiomers of methyl lactate or methyl-2-chloropropionate. In a next step, these sensors have been used to not only qualitatively determine the nature of the respective enantiomer or to quantitatively measure its concentration upon dosage in the pure form but to also assess the enantiomeric composition of mixtures by using only a single capacitive-type sensor. The enantioselective coating material consisted of a modified gamma-cyclodextrin. It was shown that the absorption and desorption kinetics of the two enantiomers of, e.g., the methyl-2-chloropropionate, are sufficiently different and produce sensor signal features that enable an accurate determination of the enantiomeric purity and composition of the chiral analyte or mixture under investigation. The method even allows for detecting small impurities in commercially available samples labeled as 99% enantiomerically pure. Moreover, the results disclosed here show that sensor techniques can be used to reveal details of enantioselective analyte-receptor and analyte-matrix interactions.
authors.affiliation: Department of Biosystems Science and Engineering, ETH Zürich, CH-4058 Basel, Switzerland.
authors.forename: Petra
authors.initials: P
authors.lastname: Kurzawski
authors.forename: Anja
authors.initials: A
authors.lastname: Bogdanski
authors.forename: Volker
authors.initials: V
authors.lastname: Schurig
authors.forename: Reinhard
authors.initials: R
authors.lastname: Wimmer
authors.forename: Andreas
authors.initials: A
authors.lastname: Hierlemann
mesh_terms: D006843:Hydrocarbons, Chlorinated; D007773:Lactates / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D011422:Propionates / Q000737:chemistry*; D013237:Stereoisomerism; D047408:gamma-Cyclodextrins / Q000737:chemistry*
chemical_list: D006843:Hydrocarbons, Chlorinated; D007773:Lactates; D011422:Propionates; D047408:gamma-Cyclodextrins; C028444:methyl lactate; C021974:2-chloropropionic acid; C023792:gamma-cyclodextrin