You state you plan to use methanol to extract something from a plant. ???

You have not provided enough information to answer your question. No one can provide you with meaningful advice regarding the exact separation conditions to use when NO SAMPLE INFORMATION has been provided. You want free help? You need to put in some effort first to explain to everyone exactly what your project is, what your goals are, what you have already done to achieve those goals and what your observations are. Identify the plant. Identify what you propose to find and how you plan to do it. Research it, yourself. Develop a hypothesis, test it, review the results with those more experienced as well as your fellow students. This is the scientific method.

Analytical LC methods are developed based on the chemical and physical properties of each sample. Without knowledge of these properties, no HPLC method can be suggested. To blindly suggest using methanol or acetonitrile, with or without acidification are just generic statements. I asked if you had done any research into your question? IOW: What are you trying to analyze? Which compounds are normally present? Which methods have been shown to be useful in retaining them? Resolve, separate and identify them.

Did you try a search first? The effort you put into learning will pay off in better understanding.

You state you plan to use methanol to extract something from a plant. ???

You have not provided enough information to answer your question. No one can provide you with meaningful advice regarding the exact separation conditions to use when NO SAMPLE INFORMATION has been provided. You want free help? You need to put in some effort first to explain to everyone exactly what your project is, what your goals are, what you have already done to achieve those goals and what your observations are. Identify the plant. Identify what you propose to find and how you plan to do it. Research it, yourself. Develop a hypothesis, test it, review the results with those more experienced as well as your fellow students. This is the scientific method.

Analytical LC methods are developed based on the chemical and physical properties of each sample. Without knowledge of these properties, no HPLC method can be suggested. To blindly suggest using methanol or acetonitrile, with or without acidification are just generic statements. I asked if you had done any research into your question? IOW: What are you trying to analyze? Which compounds are normally present? Which methods have been shown to be useful in retaining them? Resolve, separate and identify them.

What do you mean by methanolic plant extraction? Plant extraction in methanol or any other special aspect? In HPLC normally we use extraction solution as a mobile phase. As a example, when we dissolve aflatoxin in methanol, the MP also a methanol solutin. Think about it..

SAMPLE INFORMATION:

1) Plant extracts which are

2) Soluble in methanol

After doing preliminary investigation, it is understood about the MOBILE PHASE that the various percentage of METHANOL: WATER will be useful along with the addition of ACETONITRILE for achieving a better resolution of peaks.