Should I store my C-18 column in 100% organic modifier like the Waters reps. advise or 50% like I have read elsewhere?

Anon, 100% is a great idea, MeOH or ACN. I like to store mine in 80:20 ACN:Water so it will be somewhat ready for partial aqueous mobile phase. Dan.

I would be careful storing columns in 100% oraganic. I say this beacuse if 100% phosphate buffer was to be used after they had been stored in 100% oragic it may "crash" out causing a blockage. I tend to store all my columns in Water/MeOH 1:1 to be on the safe side.

I store my RP columns in 50% Acetornitrile with 0.1% TFA or acetic acid. Is it neccessary to flush the column of the acid before storage?

Raj

You should wash the buffer out of a column before sorage. If you care about column life, you should store it in 100% organic. If you store the column in 50% organic with TFA, you make the salesman happy.

For storing a RP column a long time it has been indicated that 100% iso-propanol or n-propanol are even safer than the more polar MeOH or CH3CN. If you donīt remember what is in a stored column, donīt ever restart it with a buffer thatīs insoluble in organics.

Anonymous (on Sunday, November 18, 2001 - 01:16 pm) and HW Mueller (Sunday, November 18, 2001 - 11:52 pm)

Thanks....

I've found a good practice is to flush RP columns with 20:80 ACN/water (or MeOH/water if using that combination) after using organic/buffer mobile phases. After that flush, follow with 100% ACN for best column lifetime. When starting up the next time, I typically connect the column, establish a baseline with 100% ACN, set up automated sequence with ACN/water (or MeOH/water) method (with starting gradient organic/water composition or isocratic composition) followed by gradient blanks or several "throwaway" standard and/or sample runs for isocratic methods. Before setting up any manual or automated sequences, purge solvent channel to be used with buffer first with water, then buffer, then water again, then organic solvent to avoid any chance of buffer precipitation.