Write An Essay On Gas Chromatography

Table of Contents 0
1. Introduction 2
2. Chromatography 2
2.1. Polarity 2
Gas Chromatography 3
3.1 Quantitative Analysis 4
3.2. 5 factors the affect GC separations. 6
Conclusion 6

1. Introduction
Gas chromatography is a major tool in analysis. It’s a term used to describe the group of analytical separation techniques used to analyse substances in the gas phase. The samples components are dissolved in a solvent. The components are then vaporised to separate the analytes into 2 phases: Stationary phase and Mobile phase.

2. Chromatography
The word chromatography was used by the Russian botanist Mikhail Tswett in 1903 to describe the separation of plant pigments. (Kealey, 2000, p. 80)
It is a method of separating and identifying the components

Polarity
Polarity has a huge effect on how attracted a chemical is to a substance. Some molecules are positively charged and some are negatively charged. The polarity of a molecule depends on how large the charge difference is.
As polarity of the solvent increases the components move faster during a chromatography experiment. In chromatography “like is attracted to like”. A polar solvent will be attracted to a polar solute and vice versa. Fig 1: Different Compounds with different solubility. (Anon., 2012)
Gas Chromatography
So called because the mobile phase is gas. It comprises of Gas Liquid Chromatography and Gas Solid Chromatography. For GLC the stationary phase is a high boiling liquid. In GSC the stationary phase is a solid and adsorption plays the major role. (Kealey, 2000, p. 93)
Gas chromatography is an analytical technique that is commonly used in many research and industrial laboratories for quality control and also for the identification and quantification of different compounds. It has a very wide spread use almost entirely for organic materials. It is a very rapid and simple technique that can cope with very complex mixtures. (Kealey, 2000, p.

Some detectors respond to any solute eluting from the column, others may only respond to a solute with a specific structure. (Catalogue, 2016) Table 1: Shows the different GC detectors and their limits. (Larsen, 2016)
3.1 Quantitative Analysis
Gas chromatography owes its enormous growth in part to its speed, simplicity, low cost and applicability to separations.
Quantitative gas chromatography is based on comparison on the height or the area of an analyte peak with some standards. Peak heights are easily measured, however, and, for narrow peaks accurately determined. Nowadays most chromatographic instruments are equipped with the technology that provides accurate measurements and results of relative peak areas. (Skoog, et al., 2004, p. 964)
Gas chromatography has many uses in the pharmaceutical industry. GC analyses are easy to automate from sample introduction to separation. The better the separation in GC the easier the quantification.
GC is used as quality control purposes in the pharmaceutical industry. It is widely used as a routine analytical technique in pharmaceutical quantitative analysis (Essays,