title: Retention and selectivity properties of carbamate pesticides on novel polar-embedded stationary phases.
abstract: This study describes the use of stationary phases with polar functionality suitable for the chemical analysis of carbamates pesticides and comparing with conventional alkyl C8 and C18 phases. The emphasis of this study was to compare the selectivity and retention of the pesticides on different stationary phases, bonded onto 1.7 microm partially porous silica particles under isocratic separation condition. Four stationary phases including: phenylaminopropyl (PAP) phase, bidentate propylurea-C18 (BPUC(18)), C8 and C18, were successfully bonded on the partially porous silica spheres as evidenced by (29)Si and (13)C solid-state NMR analysis. The phenylaminopropyl phase exhibited smaller retentivity and enhanced selectivity compared to the alkyl C8 phase; the analysis time to run separation of the six carbamate pesticides (i.e., methomyl, propoxur, carbofuran, carbaryl, isoprocarb, and promecarb) on the PAP phase was threefold faster than alkyl C8 phase. In a similar manner, the BPUC(18) phase shows similar selectivity to that of the PAP phase, but with longer retentivity; although the BPUC(18) phase is characterized with a lesser degree of retentivity for the carbamate pesticides than the conventional alkyl C18 phase. We propose that pi-pi and weak polar interactions between the carbamate pesticides and the PAP phase dominates the separation mechanism and providing a superior selectivity; faster separation time was also achieved as a result of smaller retentivity. Whereas the C8 and C18 bonded phases exhibits only hydrophobic interactions with the pesticides, leading to larger retentivity. The BPUC(18) phase is shown to interact via polar-polar interactions in addition to hydrophobic interactions with the pesticides, providing similar selectivity with the PAP phase but with larger retentivity.
authors.affiliation: Department of Chemistry, Irish Separation Science Cluster (ISSC), Analytical & Biological Chemistry Research Facility (ABCRF), University College Cork, Cork, Ireland.
authors.forename: Jesse O
authors.initials: JO
authors.lastname: Omamogho
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Stack
authors.forename: Apichai
authors.initials: A
authors.lastname: Santalad
authors.forename: Supalax
authors.initials: S
authors.lastname: Srijaranai
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Glennon
authors.forename: Helen
authors.initials: H
authors.lastname: Yamen
authors.forename: Klaus
authors.initials: K
authors.lastname: Albert
mesh_terms: D002219:Carbamates / Q000032:analysis*; D002247:Carbon Isotopes; D002853:Chromatography, Liquid / Q000379:methods*; D057927:Hydrophobic and Hydrophilic Interactions; D007554:Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010575:Pesticides / Q000032:analysis*; D012825:Silicon
chemical_list: D002219:Carbamates; D002247:Carbon Isotopes; D007554:Isotopes; D010575:Pesticides; D012825:Silicon