High performance liquid chromatography

Seagrass meadows in Florida Bay have rapidly declined due to synergistic stresses. The microalgal communities present on the leaves of Thalssia testudinum were studied in the Snake Bight and Whipray Basin areas of Florida Bay. These areas have been the sites of recurrent phytoplankton blooms and this study was aimed at exploring similar effects within the microalgal epiphytic communities. Epiphytometers, or surrogate seagrass, were used to provide a time zero (T0) point which is impossible in natural samples. Epiphyte samples were analyzed using HPLC/PDA which provided measurements of standing crop and community structure (>90% diatom). Epiphytometers were found to be excellent tool for monitoring epiphyte productivity on Thalassia. The monitoring of productivity, standing crop and community structure should allow insight into positive and negative effects of water supply changes.

Chromatographic stability studies of an alumina-based reversed phase, ODA, stationary phase were performed. These studies involved monitoring the chromatographic performance of columns packed with the ODA phase after separate, continuous treatment with aqueous solutions of trifluoroacetic acid and sodium hydroxide over a period of several weeks. Chromatographic performance of the ODA columns undergoing treatment with these mobile phases was evaluated by comparing changes in chromatographic capacity factors, resolutions, plate numbers, and peak asymmetries of a test mixture consisting of uracil, phenol, aniline, methyl benzoate, m-toluidine, N,N-dimethylaniline, and toluene. The results indicate that the alumina-based ODA phase is stable under acidic conditions (pH 2--3) and exceptionally stable to chemical degradation under alkaline conditions (pH ∼ 11).