Perhaps it has already been done. Let us suppose that the literature review reveals that the project has not been done. Reviewers still want to know why this proposal should be funded. It is important to carefully explain the significance of the research. You must convince the reviewer that you know what you are talking about and the experiments are indeed feasible.
Details here are important.
If you are proposing to use HPLC for a particular analysis, give the column, detector, solvent, and any other parameters that you will use. If the analysis has been published, give a literature citation. Once again, you must be specific. A well thought out budget is essential. It is important not to cut costs to the point where the project cannot be accomplished.