3 What you’ll be doing in this investigation

In this investigation you will be using the technique of gas chromatography together with mass spectrometry (a combination also known as ‘GC–MS’) to evaluate the environmental contamination of a tidal bay in China by the class of persistent organochlorine pesticide.

You will first develop a hypothesis and sampling plan, choosing which sites to sample in the bay. You will then use GC–MS qualitatively to identify any pesticides present in your samples and quantitatively to determine the concentrations of the pesticides you have found.

By the end of this investigation you should be able to:

• devise a sampling plan
• understand how chromatography is used to separate mixtures of compounds
• compare mass spectra of individual pesticides with a ‘pesticide’ library to identify particular compounds present in a mixture
• determine the concentrations of individual pesticides present in a sample