Abstract
Analysis within chemistry comes in two formats; these include
qualitative (aimed towards indicating the quality of the sample and
therefore the purity) and quantitative analysis (used to identify how
much of a compound is within a molecule for example). Using
qualitative and quantitative analysis, it was possible for me to create an
outreach workbook named ‘An introduction to analytical Chemistry’,
using the methods below.
Chromatography
Many different practical techniques can be used within analytical chemistry;
examples include chromatography, which can be used to simply identify
different colours in a specific ink, but also to indicate the levels of different
compounds within liquids and gases.
Spectrophotometry
The ability to measure a compound / compounds is an essential skill
required in many areas of science. The most widely used method of doing
so is with a technique called UV/visible Spectrophotometry. This method is
based upon the fact that light interacts with molecules in a way which
means that the material within the molecule can be identified.
The spectra produced to show the results from gas and liquid chromatography
can be used to identify unknown compounds, which makes the method useful
within forensic sciences.
Methods of separation like chromatography are becoming increasingly more
popular and can even be used in drugs trials within the Olympics.
Spectrophotometers contain a light source which emits white light; this
then gets split into all of the contributing colours. Individual colours are
directed towards the sample which can then absorb or transmit light. Light
detectors then calculate the light which was both absorbed and
transmitted, identifying the compound.
Titrations
Titrations are a form of quantitative analysis and help to calculate how much of
one substance is needed to react with a given amount of another substance.
The vitamin C titration, carried out within the workbook, is a redox titration
between as vitamin C and Iodine. Starch is used in the titration as an indicator.
The titration is carried out to find out the content of vitamin C within Vitamin C
supplements. Data can then be used to compare and contrast the different levels
of Vitamin C within the two different supplements.
Flame Photometry
Flame photometry (also known as flame atomic emission
Spectrophotometry) is widely used to accurately measure the
concentrations of alkaline metal ions (such as Na⁺ and K⁺) within water
samples and samples of biological fluids. Flame photometers can
therefore be used to detect the concentrations of pure metals.
Due to this, flame photometry is a method of quantitative analysis.
The main principal for flame photometry, is the fact that the compounds
which make up the alkaline metals can be thermally dissociated. When this
occurs, some of the atoms produced by the thermal dissociation can step up
to higher level of energy. Once the atoms involved return once more to
ground state, they emit radiation; some of this is visible as light. Each alkaline
metal produces radiation at different wavelengths therefore the colours
produced vary.
Repeating titrations makes for better results, as this can determine whether or
not results are accurate and fluent, this often means that the first run of a
titration is usually used as a rough guide for when the titration will be complete.
Conclusions
Each of the methods mentioned above
contribute towards analytical chemistry and
are therefore presented in the final outcome of
the outreach booklet.
Methods used in analytical chemistry like
chromatography and titrations often need to
be repeated to determine correct results and
collaboration.