Your Question -

 What protocol do you use to clean the RP C18 HPLC column daily?

I am running 30-50 samples/day I wonder if I need to do regular cleaning after use. My mobile phase 5% acetic acid-methanol-acetonitrile 70:15:15. What solvent do you suggest?

Answer - I usually make morning wash and night wash for column C18 RP, befor and after working in the end of the day.

The morning wash is consist of four stages; each stage about 10 minutes

1) 10% acetonitrile+90%water

2) 100% Methanol

3) 100% Acetonitrile

4) 100% mobile phase

The night wash is consist of four stagese too.

1) 10% acetonitrile+ 90% water

2) 100% Methanol

3) 100% Acetonitrile

4) 80% Acetonitrile+20% Water

This will longer the age of column what ever you work  on the column.