Retention and selectivity properties of carbamate pesticides on novel polar-embedded stationary phases

• Published in: Analytical and bioanalytical chemistry 2010-07, Vol.397 (6), p.2513-2524
• Main Authors: Omamogho, Jesse O, Stack, Elaine M, Santalad, Apichai, Srijaranai, Supalax, Glennon, Jeremy D, Yamen, Helen, Albert, Klaus
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Biochemistry; carbamate pesticides; Carbamates; Carbamates - analysis; Carbon Isotopes; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Chromatography, Liquid - methods; Comparative analysis; Core-shell silica; Enzyme inhibitors; Exact sciences and technology; Food Science; Hydrophobic and Hydrophilic Interactions; Isotopes; Laboratory Medicine; Magnetic Resonance Spectroscopy - methods; Mathematical analysis; Monitoring/Environmental Analysis; Original Paper; Pesticides; Pesticides - analysis; Phases; Polar-embedded phase; Seeded growth mesoporous shell; Selectivity; Silica; Silicon; Spectrometric and optical methods
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-010-3816-3

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 µm partially porous silica particles under isocratic separation condition. Four stationary phases including: phenylaminopropyl (PAP) phase, bidentate propylurea-C18 (BPUC₁₈), C8 and C18, were successfully bonded on the partially porous silica spheres as evidenced by ²⁹Si and ¹³C 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 BPUC₁₈ phase shows similar selectivity to that of the PAP phase, but with longer retentivity; although the BPUC₁₈ phase is characterized with a lesser degree of retentivity for the carbamate pesticides than the conventional alkyl C18 phase. We propose that π-π 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 BPUC₁₈ 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. [graphic removed]