ARS | Publication request: HILIC separation mechanisms of tetracyclines on amino bonded silica column

Submitted to: Journal of Separation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 11, 2011
Publication Date: July 1, 2011
Citation: Li, R., Zhang, Y., Lee, C.C., Liu, L., Huang, Y. 2011. HILIC separation mechanisms of tetracyclines on amino bonded silica column. Journal of Separation Science. 34(13):1508-1516.

Interpretive Summary: Antibiotic tetracyclines are important industrial chemicals that are used in the animal husbandry sector. A significant fraction of the applied tetracyclines are not absorbed by the animals and are excreted into environmental waters. Given the heavy use of these antibiotics, monitoring of their levels in environmental waters is of critical importance to the protection of human health and the environment. This report describes the development of a simple, precise, and accurate chromatographic method for the determination of four tetracycline antibiotics in environmental water samples.

Technical Abstract: Effects of mobile phase variations on the chromatographic separation on amino bonded silica column in hydrophilic interaction chromatography (HILIC) were investigated for four zwitterionic tetracyclines (TCs): oxytetracycline, doxycycline, chlortetracycline and tetracycline. A mixed-mode retention mechanism composed of partitioning, adsorption and ion exchange interactions was proposed for the amino HILIC retention process. Buffer type and pH significantly influenced the retention of TCs, but showed similar separation selectivity for the tested analytes. Experiments varying buffer salt concentration and pH demonstrated the presence of ion exchange interactions in TCs retention. The type and concentration of organic modifier also affected the retention and selectivity of the analytes, providing direct evidence supporting the Alpert retention model for HILIC. The retention time of the analytes increased in the following order of organic modifiers: tetrahydrofuran < methanol < isopropanol < acetonitrile. The linear relationships of logk′ versus %water (v/v) curve and logk′ versus logarithm of %water (v/v) in the mobile phase indicated that TCs separation on the amino phase was controlled by partitioning and adsorption. The developed method was successfully utilized in the detection of TCs in both river water and wastewater samples using solid phase extraction (SPE) for sample clean-up.