To adapt your HPLC method from a 9.4 x 150 mm column to a 4.6 x 250 mm column, reduce the flow rate to approximately 0.5-0.7 mL/min and decrease the organic solvent percentage in the mobile phase by 5-10%. Further optimization may be needed based on retention times and peak resolution.

Column DIMENSIONS can be scaled (same exact column type). Information on your actual sample, method and instrument (with chromatograms) would be needed to answer your question and a web forum is not the best place to answer such a complex question. However, here is an easy to understand authoritative article on how to adjust for column dimension changes. "Adjusting the HPLC Gradient Time For Changes in Column Diameter and/or Length (same particle size)"; https://hplctips.blogspot.com/2022/01/adjusting-hplc-gradient-time-for.html

"HPLC Column Cross-Sectional Area and Scaling"; https://hplctips.blogspot.com/2020/04/hplc-column-cross-sectional-area-and.html

NOTE: Please contact an experienced local chromatographer to assist you in properly scaling the LC method to use a column with different dimensions on your HPLC system. Column dimensions are one of several areas that may need to be re-adapted. Parameters for the particle size, flow cell dimensions/volume, mobile phase composition, sample preparation, injection volume etc may also need to be adjusted and making these changes will require the assistance of an experienced chromatographer.

Faeze

Start with online free tools like:

https://appslab.thermofisher.com/lc-method-transfer-calculator

https://www.phenomenex.com/tools/lc-transfer?srsltid=AfmBOopZGHt5FBRcT08rrnI_jX1GO2hGsrzeFCfiJ5kO12hF4kZBWAyF

https://www.sigmaaldrich.com/CL/es/support/calculators-and-apps/hplc-method-transfer-calculator?srsltid=AfmBOor0dFBbsSWsyGuqyRkqRdhQMcYGtRpkORhNm9r2nObhDrruVg5O

There are others online

Regards

Sebastián Finger

Thanks