We are in search for literature concerning miniaturization.

We are planning to reduce column i.d. from 4,0mm to 2-3mm.

Thanks

Try this link:
http://www.lcgceurope.com/lcgceurope/data/articlestandard/lcgceurope/032002/7351/article.pdf

match up the mobile phase linear velocity. you may need to reduce the injection volume if your sample is in solvent stronger than mobile phase, we usually use 5ul injection size with 2.1 mm columns, sometimes 10ul. For example, 1.00 ml/min with 4.6 mm column became 0.25 ml/min with 2.1 mm column, or 0.5 ml/min with 3 mm column. great way to conserve mobile phase and reduce waste solvent volume.