Chromatography Forum

We are analysing low quantities of modified oligonucleotides on a Pharmacia MonoQ anion exchange column. Our eluant system is a gradient system running from 1mmNaOH in 0.2MNaCl to 1mm NaOH in 1.4M NaCl .
The only LC's we have suitable for this work are Waters standard stainless steel systems(with a seal wash). I am worried we will damage the pumps/detectors and autosamplers using these eluants, even if the seals are on a constant wash system and the whole systems are thoroughly rinsed overnight.
Has anyone experience of using 316SS and Molar salt solutions long term?
Thanks!

We have tested such eluents, and you will have corrosion eventually. Genentech has also seen this problem with their SST systems. You will have early warning because corrosion will have drastic effects on your chromatography. You can reduce the severity by deoxygenating the eluents, and replacing any SST filter frits with Ti or PEEK. Passivating your system every few months will also help to remove corrosion and suppress formation of more rust (see the recent thread on SST capillary tubing). Increase the frequency of service and fix leaks immediately. Don't forget to inspect and clean the injector valve; that can get ugly. If you have an option to upgrade components to Ti or PEEK, spend that money.

Chloride and stainless steel do not like each other. How about substituting the salt with sodium sulfate or other non-halide salts.

Changing the anion changes the selectivity of the separation. I you can afford the time to redevelop the separation, try perchlorate. We have had good results with that on our DNAPac columns: http://www1.dionex.com/en-us/columns_ac ... 60685.html