The IMRAD structure
The Introduction should discuss why you did the research and
why is it valuable or necessary? This should be complemented by an
expert understanding of prior work in this field, typically via a
literature review, placing the significance of your research among the
scientific record. A useful guide on how to structure ones introduction is offered by Boyd \cite{Boyd_2012}. While this guidance is offered in respect to the Mass spectrometry discipline it offers an extremely useful method for the structuring of an introduction. In the Boydian method, the introduction should be considered in 4 parts or subsections. The first 3 of which provide a "drill-down" from the general to the specific, topped off with a final sub-section discussing the objective of the work as a segway into the experimental section.
[use MRC example to demonstrate sections]
Sub section 1 - broad context behind the experiment
Sub section 2 - narrowing down
Sub section 3 - zeroes in on the specific problem, more detailed review of the literature specific to the investigation, with an expert theoretical and experimental critique. Be cautious in this section to keep the literature review relevant, focus on research that are directly relevant to the topic at hand and avoid pulling in literature that may be extraneous to the thrust of your research. \cite{Hoogenboom2012}
Sub section 4 - objective of the present work