Benefits of Split /Splitless Injection in Capillary Gas Chromatography

Benefits of split/splitless injection in Gas Chromatographic detection gives you the freedom of changing the amount of sample component entering the capillary column.

Splitless mode – Split Valve Closed

Split mode – Split Valve Partialy open

Split mode - Split Valve Partialy open

At times you may get a broad flat top peak instead of a sharp well-defined peak. In such situations you have the following options available:

  • Dilute the sample
  • Attenuate the signal
  • Use split mode injection

The first two options are hit and trial manual exercises and often take up substantial amount of valuable time.

In the split/splitless mode using software control a valve changes the proportion of the injected sample component that would reach the column head. Split valve controls the amount of sample entering the column, say in the proportion 100:1, i.e, for every hundred parts only one part enters the column and the remaining part is vented out. The settings can be stored in the analytical method for getting reproducible analysis every time.

The split mode achieves online dilution of the sample without the need for adding diluting solvent to the injected sample. This holds for analysis when the concentration of sample component overloads the column and results in a broad peak. We shall now look into a situation where the components of interest are present in trace levels. The classical approach would be to pre – concentrate the sample before injection which is again a time-consuming activity.

Resorting to split test mode through the software will shut the split valve in a programmed manner to permit majority of the sample to reach the column. This will result in enhancement of peaks of trace components.

We have seen that the split/ splitless injection mode offers you the benefit of analysis of sample components over a vast concentration range without the need for time-consuming sample dilutions or pre-concentrations. All modern PC systems provide this facility at the simple click of the software.

After going through the article you will like to share your experiences on working over a vast range of concentrations of components and impurities of your interest.

About Dr. Deepak Bhanot

Dr Deepak Bhanot is a seasoned professional having nearly 30 years expertise beginning from sales and product support of analytical instruments. After completing his graduation and post graduation from Delhi University and IIT Delhi he went on to Loughborough University of Technology, UK for doctorate research in analytical chemistry. His mission is to develop training programs on analytical techniques and share his experiences with broad spectrum of users ranging from professionals engaged in analytical development and research as well as young enthusiasts fresh from academics who wish to embark upon a career in analytical industry.

Comments

  1. Sir,
    I extend my sincere greetings and thanks for the wonderful and informative articles posted regarding various analytical techniques. May I request you to bring out articles on easy techniques adopted for sample extraction, concentration and the different solvents / techniques used for the analysis of pesticides in water samples using GC
    Thanks and Regards
    Anita

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