Chemical Analysis

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  • Created by: Amy
  • Created on: 28-04-13 16:00

Chemical Analysis

whats in the substance? 

additives may be added to food and food scientists can analyse the food and identify the additives, modern instruments provide fast, accurate and sensitive ways of analyzing chemical substances, 

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Instumental Methods


  • onky need a small amount of the sample
  • dosnt use toxic methods
  • quick
  • sensitive
  • accurate
  • reliable


  • machines need energy to run
  • equipment is expensive
  • traind chemists are needed to analize results


  • forensic
  • health
  • environmental
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Paper Chromatograpghy

  • used for dyes and pigments
  • dots of single dyes are placed alongside a dot of unknown mixture on a piece of chromatograghy paper
  • placed in a solvent
  • solvent seeps up the paper, taking the dyes with it
  • dyes form spots in different places
  • patten of the singles dydes can be compared to that of the mixture
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Gas Chromatography

  • used in analytical labs
  • drug testing
  • moblie phase is inert gas
  • gas is used to carry the substance through a column 
  • substance travels through the tube at different speeds, so they are seperated
  • some substances are more attracted to the matrix than others - take longer to react
  • retention time - time taken to reach the detector
  • data plotted on a graph - the number of the peaks show the number of different compounds in the sample & the position of the peaks shows the retention time of each substance
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Mass Spectrometry

  • gas chromatography linked to a mass spectrometre = GC-MS
  • identifys the substance leaving the column v. accuratly
  • the mass spectrometer can be used to find the relative molecular mass of a compound from its molecular ion peak
  • molecular ion peak - found as the last peak on the right as you look at the mass spectrum.
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Key Points

  • compounds in a mixture can be separated using gas chromatography
  • once seperated, compounds can be identified using a mass spectrometer
  • the mass spectrometer can be used to find the relative molecular mass of a compound from its molecular ion peak (found as the last peack on the right)
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