• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Chromatography Investigation

Extracts from this document...


Introduction Chromatography is a highly regarded technique used to separate the components of a mixture. It is based on the principle that each component possesses a unique affinity for a stationary phase and a mobile phase. The components that are more inclined to enter the mobile phase will migrate further on the chromatogram and distinguish themselves from the other components. The type of solvent used in chromatography is known to directly affect the separation of the mixture. In this experiment, thin-layer and column chromatography will be utilized to separate the numerous chlorophyll and carotenoid pigments of a spinach extract. The optimal solvent that will maximize the resolution of the components on the chromatogram will be exhibited. Procedure The procedure is described in the Chemistry 282 Laboratory Manual (Department of chemistry, 2002). A minor change to the experiment was the use of magnesium sulfate to dehydrate the organic layer instead of sodium sulfate. Discussion Thin-layer chromatography (TLC) is a technique that involves the movement of the components of a mixture up a plate with the use of a solvent. ...read more.


For example, a more polar solvent will compete with the polar components for positions on the polar adsorbent and also transport its counterpart along the plate until it finally becomes adsorbed. As a result, the polar components of the mixture will remain in the mobile phase for a longer period and thus travel a larger distance along the plate. However, the use of a non-polar solvent will cause the polar components to remain stationary since they have a much larger attraction for the adsorbent than the mobile solvent. In this experiment, three solvents of different polarities were used to separate the pigments in the plant extract. The 9:1 hexanes-acetone solvent was the least polar of the three and was the most unsuccessful solvent in separating the extract, as it only distinguished two pigments. This result may attribute to the solvent's incompetence in both converting the polar components of the extract into the mobile phase and blocking the binding positions on the stationary adsorbent. ...read more.


There were a few instances throughout the experiment that may have slightly altered the obtained results. Firstly, the lid to the jar was left open for short periods, which may have caused the more volatile acetone to evaporate. Consequently, the hexanes-acetone ratio might have been hindered, resulting in a more non-polar solvent. Secondly, the sample on the 5:5 hexanes-acetone plates may have been overloaded because the sample ran as a streak near the origin. The streak distorted the illustration of the pigments on the chromatogram, making them difficult to distinguish. Conclusions The best solvent used to separate the components of the spinach extract was determined to be a 7:3 hexanes-acetone mixture because it divided the spinach extract into the greatest number of components. Additionally, thin-layer chromatography provided evidence that the pigment beta-carotene was present in spinach, as a yellow-orange pigment encompassed identical retention factor values on every plate. This experiment may be improved through the use of a longer TLC plate. A longer plate will magnify the migration distances of each component, which will make them easier to distinguish on the chromatogram. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Hazardous Environments section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Hazardous Environments essays

  1. A Report Of The Investigation into Health and Safety In The Workplace

    Health and safety at the Central Science Laboratory The laboratory contains many hazards. However, if you recognise the hazards and their possible dangers you can eliminate or at least minimise the risk. In the laboratory a bottle of concentrated sulphuric acid is a hazard.

  2. Title : The Determination of Microbial Numbers Objectives:Practically every phase of microbiology requires ...

    As we seen in the result, the distribution of the colonies are sometimes colonize certain area of the Petri plate. I think the main reason is cause by uneven mixing of the molten agar. To enhance the accuracy, I think we should duplicate the result and compare it with other

  1. Preparation of media and reagents & aseptic technique and pure culture

    The lids should also face downwards separately from the base of the plate. The plates are leaved at 45 - 55�C for 15 min. The agar plates can be stored for at least a few weeks at 4�C following wrapping in parafilm or sealing in a plastic bag.

  2. Free essay

    Extreme Weather Investigation

    To make the rainfall itself we had to use a length of guttering (the same size as the plots) with lots of pierced holes throughout. We began the experiment by placing the guttering directly above each plots and then pouring water into the guttering thus making rainfall.

  1. A Report Of The Investigation into Health and Safety In The Workplace.

    The last heading is the Signature of assessor, which is where you sign your name. Hazards Below are all the hazard signs, with their meanings below them, I could find on the website http://www.tapex.com.au/Safety/html/hazard.htm Health And Safety At Graham School Hazards The sorts of hazards we have at Graham aren't

  2. The origin of the Earth

    which has revolutionized thinking in the Earth's sciences in the last 10 years. The theory of plate tectonics combines many of the ideas about continental drift and sea-floor spreading. The lithosphere covers the whole Earth. Therefore, ocean plates are also involved, more particularly in the process of sea-floor spreading.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work