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Chromatography in Process Analysis

Process Instrumental Methods

  1. Jerry M. Clemons

Published Online: 15 MAR 2011

DOI: 10.1002/9780470027318.a2107.pub2

Encyclopedia of Analytical Chemistry

Encyclopedia of Analytical Chemistry

How to Cite

Clemons, J. M. 2011. Chromatography in Process Analysis. Encyclopedia of Analytical Chemistry. .

Author Information

  1. ABB Process Analytics, Lewisburg, WV, USA

Publication History

  1. Published Online: 15 MAR 2011

Abstract

Process chromatography is an analytical technique that provides for the on-line separation and measurement of the components of a mixture in a chemical process. The chromatographic analyzers utilized for on-line analysis must operate in a continuous and automatic manner, taking a fixed quantity of sample, separating the chemical components using adsorption or partitioning columns, and measuring the concentration of each with a detector. The chromatograph provides both quantitative results, by measuring the area of the peak generated as the components pass through the detector, and qualitative results based on the retention time, which is measured from injection to detection.

The most commonly used process chromatographic analyzer is the process gas chromatograph because of its many applications in the hydrocarbon processing industry. A variety of valve, column, and detector configurations are available for these analyses, from parts per million to percent levels. All samples must be in gas phase or must be liquids that can be vaporized prior to analysis. The analyzers are controlled using a cyclic timing device that switches valves and columns as the components pass through the system to provide the necessary separation. This time cycle is a limitation of the technique for applications requiring continuous or very fast analysis times. Even with these limitations, the advantages of cost, flexibility, sensitivity, and reliability have made process gas chromatography (PGC) the most widely used analytical technique for on-line process control.

Keywords:

  • process gas chromatography;
  • carrier gas;
  • sample valves;
  • column switching valves;
  • columns;
  • detectors;
  • data systems;
  • application engineering;
  • sample systems;
  • process liquid chromatography;
  • supercritical fluid chromatography;
  • preparative-scale chromatography