title: One- and two-dimensional direct chiral liquid chromatographic determination of mixtures of diclofop-Acid and diclofop-methyl herbicides.
abstract: Simple one- and two-dimensional high-performance liquid chromatography (HPLC) methods for the simultaneous enantiomeric determination of alkyloxyphenoxypropionic acid herbicides is presented. Compounds studied were ( R, S)-2-[4-(2,4-dichlorophenoxy)phenoxy]propionic acid (diclofop-acid) and ( R, S)-2-[4-(2,4-dichlorophenoxy)]methyl propionate (diclofop-methyl). Mobile phases necessary to separate their enantiomers on an alpha1-acid glycoprotein chiral stationary phase are different; therefore, the simultaneous separation by an isocratic mode is not possible. The chiral separation method proposed involves a one-step gradient allowing for the simultaneous determination of both racemic enantiomers. Detection limits of the method were 0.03 mg/L for both diclofop-acid enantiomers and 0.14 and 0.15 mg/L for diclofop-methyl enantiomers, respectively. The two-dimensional method involves the use of two chromatographs in one achiral-chiral coupling. The LC-LC method is more suitable for complex samples because it involves an online cleanup effect. Detection limits were 1.25 and 1.87 mg/L for diclofop-acid and 2.70 and 3.02 mg/L for diclofop-methyl enantiomers, respectively. Accuracy, repeatability, and reproducibility have been studied in standard samples and a technical product.
authors.affiliation: Departamento de Química Analítica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Guillén-Casla
authors.forename: Luis Vicente
authors.initials: LV
authors.lastname: Pérez-Arribas
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: León-González
authors.forename: Luis María
authors.initials: LM
authors.lastname: Polo-Díez
mesh_terms: D002396:Catechols; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D055768:Halogenated Diphenyl Ethers; D006540:Herbicides / Q000032:analysis*; D010647:Phenyl Ethers / Q000032:analysis*; D011422:Propionates / Q000032:analysis*; D011786:Quality Control; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013237:Stereoisomerism
chemical_list: C473754:2,4-dichlorophenoxypropionic acid; C529887:2-(4-(2,4-dichlorophenoxy)phenoxy)propionic acid; D002396:Catechols; D055768:Halogenated Diphenyl Ethers; D006540:Herbicides; D010647:Phenyl Ethers; D011422:Propionates; C012891:dichlorfop-methyl