Chromatography Forum

here i´m, i think watching my column die...but i´m not so sure...
i´m using a shim-pack vp-ods 250mm x 4,6 ( shimadzu) 4 months ago... it hink it´s too early my column die...i work regularly with 1 ml/min flow, with acn, Meoh, and common buffers...and i wash the column once completed my job with 80%H2O 20% MeOh daily at a 1ml/min daily...
the problem is that i begin to observe a shoulder peak in several drugs that i´m analizing, no matter the changes i´ve been doing, this awful shoulder peaks appears over and over again...
i´ll like to know how you, people, works daily...i thinks it´s ok to set 1ml/min or 0,5 or even 1,5 ml/min ( i avoid to work up to 1,5)...
i´ll apprecite any advice or tip in order to improve the column and equipment lifetime.
Thanks to all!

You have almost certainly got a void at the top of your column because you have used buffers outside the ideal pH range for the column.

In the 'old days' we would take the top off the column and fill the void with some similar packing in a methanol slurry. These days I guess most people just buy another.

In order to extend the life of a column it is best to use a guard column

i´ve never used buffer out of the column ph range, i always check the differents mixes and it´s ph in order to avoid this i guarantee (i really do this everytime), and beside i also always ´ve used a precolumn, i guarantee that too...
the column has only 4 months and 1024 inyections.
i just try with an known standard and i have a shoulder peak again, so the column is not working properly.
i´ll turn it and inyect a standard repeatedly to see what happen...
is it valid in order to fix this void that i suppose i got at the column head?

Coquim,

As said on the other site your posting on, reversing the column will at best be a temporary fix and will not "cure" a void in your column.

If you cant repack the column, your going to need a new one.

have you tried changing the guard column

i´ve just try it, and...works ok!!. the rare thing is that the the precolumn was a new one...now the peaks are without a shoulderpeak again...it´s looks simple but it wasn´t for me, i was afraid the column was dieing...

Just curious, how many injections and what are you injecting?

i've just count the number of inyections today...1024 times....but the precolumn was a new one...i think i've inyected only 100 times...i've inyected drugs like dipirone, vitamins B, furosemide etc etc, common drugs, and always with common solvents as acn, meoh, water...and i must say, ALWAYS checking before the ph...