High Performance Liquid Chromatography (HPLC)


HPLC HPLC is a chemistry based tool for quantifying and analyzing mixtures of chemical compounds. It is a technique that has been used for biotechnological, biomedical, and biochemical research as well as by the pharmaceutical industry. More recently HPLC has found a use in a variety of fields including cosmetics, food, and environmental industries. It consists of a precise gradient mixer; high pressure pumps with very constant flow; high accuracy, low dispersion, sample valves, high efficiency columns with inert packing materials, high sensitivity, low dispersion detectors, low dispersion connecting tubes for valve to column and column to detector. The columns, in general, achieve their separation by exploiting the different intermolecular forces between the solute and the stationary phase and those between the solute and the mobile phase. The column will retain those substances that interact more strongly with the stationary phase than those that interact more strongly with the mobile phase. The detector is either UV, refractive index or fluorescence.

HPLC system

Technical Specifications

The Thermo-Separation products HPLC system is modular in style and consists of:

  • Degasser that removes dissolved gas from the mobile phases so that on mixing, gas bubbles are not formed
  • High performance gradient pump system consisting of two pumps working out of phase to ensure continuous flow
  • Automatic sampler for unattended use
  • High efficiency column
  • UV detector
  • PC for data acquisition

The Main Unique Aspects Of The Machine

  • High precision detector (5 d.p. absorption units). The limit of detection varies according to the absorbance of the species but typically this equates to aspecies concentration of 0.2 ppm.
  • Column oven that ensures reproducibility of retention time.
  • Microprocessor controlled gradient pump ensuring low pulsation and therefore an even mobile-phase flow.
  • Auto sampler that allows a maximum of 120 samples to be run unattended after which a shutdown program can reduce the flow to 0.1 ml / min to reduce mobile phase loss.
  • The system is interfaced with Dionex Chromeleon v6.5 for fully automated unattended measurements and full quantification capabilities. This ensures high throughput and repeatability

Examples Of Work Undertaken At The Institute

A number of projects have used this technique for quantitative measurement.

  • Measurement of lactic acid in degradation studies of poly (lactic acid)
  • Drug releases from glass-ionomer cements including chlorhexidine acetate, chlorhexidine gluconate and amprolium hydrochloride.
  • Release of Tetracycline hydrochloride and Vancomycin from Bio-OSS.

For more information on any of the BTE facilities, please contact Professor Jonathan Knowles
Email. j.knowles@ucl.ac.uk  Tel. +44 (0)20 3456 1189