High Performance Liquid Chromatography Essay

1.5 ULTRA PERFORMANCE LIQUID CHROMATOGRAPHY (UPLC) Since from thirty years, High performance liquid Chromatography (HPLC) is well accepted technique used in laboratories worldwide. It is one of the analytical techniques used to identify, separate and quantify each analyte in a mixture. One of the primary drivers for the development of this technique has been the progression of the packing materials (particle size, packing technology, chemistry) used to impact the separation. The fundamental principles of this progression are governed by the Van Deemter equation. It is a formula describing the relationship between plate height (H) and linear velocity (flow rate). The column efficiency is measured by the number of theoretical plates in a column, N, and normalized with the column length to give HEPT (Height Equivalent Theoretical Plate) or H. The Van Deemter equation defines the various factors …show more content…
These multiple paths arise due to the difference in column packing and small variations in particle size of the packing material. As different paths are of different lengths, this causes broadening of the solute band.
B-term: Longitudinal diffusion: Longitudinal diffusion is the movement of an analyte molecule outside from the center to the edges of its band, as the analyte concentration is lower at the edges than at the center of the band. Analyte diffuses from the center to the edges. Thus band broadening occurs. If the mobile phase velocity is high, then the analyte spends less time on the column, this limit outward distribution, keeping the band