Field‐amplified sample injection combined with CE for the enantiodetermination of cathinones in urine samples. Issue 14 (17th May 2020)

• Record Type: Journal Article
• Authors: Pérez‐Alcaraz, Albert; Borrull, Francesc; Calull, Marta; Aguilar, Carme
• Is Part Of: Journal of separation science. Volume 43:Issue 14(2020)
• Page Start: 2914
• Page End: 2924
• Publication Date: 2020-05-17
• Subjects: cathinones -- chiral capillary electrophoresis -- field‐amplified sample injection -- urine analysis; Separation (Technology) -- Periodicals; Chromatographic analysis -- Periodicals; 543.089
• DOI: 10.1002/jssc.201901067
• Languages: English
• ISSNs: 1615-9306

Abstract

Abstract: This work presents a capillary electrophoresis methodology for the enantiodetermination of cathinones in urine employing a liquid–liquid extraction sample pretreatment. The cathinones were enantioseparated by adding a mixture of 8 mM 2‐hydroxypropyl β‐cyclodextrin and 5 mM β‐cyclodextrin to the background electrolyte, which consists of 70 mM of monosodium phosphate aqueous solution at pH 2.5. Field‐amplified sample injection was used as preconcentration strategy to improve the sensitivity. We studied various parameters that affect this stacking strategy, in particular, the sample solvent and its pH, the presence or absence of a low conductivity solvent plug introduced before the sample injection, the nature and volume of this plug, and the voltage and time of the electrokinetic injection of the sample. The optimum conditions were achieved by injecting a plug of isopropanol:H2 O 50/50 at 50 mbar for 5 s prior to the electrokinetic injection of the sample prepared in an aqueous solution of HCl 10 −6 M. The sensitivity enhancement factors were from 562 to 601 in terms of peak area and from 444 to 472 in terms of peak height. The method was validated by analyzing spiked urine samples, obtaining a linear range of 25 to 1000 ng/mL and limits of detection ranging from 15 to 45 ng/mL.