[John55]

hi ,
i'm desperate,could anyone help me please?

We use an analytical column to optimize the separation and then carry out a preparative separation of two substances. We have a 10 cm long preparative HPLC column with 40 separation steps per cm and an analytical column (also 10 cm) with 400 separation steps per cm. Both columns are packed with the same separating material and therefore have the same retention factors for the two components of our two-component mixture. For the preparative separation, the resolution must be at least 2. To what value do we have to optimize the resolution with the analytical column so that we can then transfer the separation to the preparative column?

[MOTOBALL]

The forum rules are that you must show some attempt at solving the problem, before we can help you.
Hence lack of response to your question.
Suggest that you write down the basic formulas of chromatographic resolution, and go from there.

Good Luck!

[Arkcon]

Here's a quick web page I found that will help you compare the two parameters: https://www.pharmaguideline.com/2011/09/resolution-factor-telling-factor.html

I would run a trial run, an analytical quantity on the prep scale column, before committing to large scale.  You should see the results conform pretty close to theoretical, if you're not overloading the column.