My column is Pico-Tag Column, 60Å, 4 µm, 3.9 mm X 150 mm used technique for HPLC amino acid analysis. Used in PicoTag® Amino Acid Analysis of Protein Hydrolysates.
You should ALWAYS consider a HPLC column as a consumable item with a finite lifetime. that lifetime can be extended with the use of a guard or pre-column and more so from quality sample preparation.
Depending on what you column looks like in terms of retention and peak shape, your column may well be past the point of no return and the only option is replacement.
After saying that, for the Pico-Tag column, which is a Nova-Pak C18 column specially certified for high reso9lution of derivitised amino acids. With the column should be a manual on the care and use of this specific column. As amino acid analysis often employ aqueous buffers, it is imperative that at end of each analytical run, ALL buffer has been well washed from the column, rule of thumb for volume solvent needed for flushing is 10 times the column volume. when flushing out buffer, don't use straight water (Milli-Q), rather have a small amount of organic solvent (acetonitrile at say 20%). Once all buffer has been well washed from the column, increase the acetonitrile to 100% and pump through 20 column volumes.
Test column efficiency again as per the care and use manual than make the assessment was all that time worth it, was the use of all that solvent worth it, was your time worth it in terms of full replacement cost.