Hi. Thankyou for your replies on alternative IC columns in my previous query. I'm new to this area, and after some background reading, have two more queries on IC with suppression system (conductivity detection):

1) Is chemical suppression still only exclusive to Dionex? Will other suppressions like electrochemically generated version infringed on Dionex licence rights?

2) Like i mentioned previously, i was thinking of using Agilent HPLC (1100 series) with Alltech ERIS suppression/conductivity meter for IC suppression analysis of inorganic anions (at < 10ppm level). Would the mobile phase ( NaHCO3/Na2Co3 etc) cause corrosion problem with stainless steel tubings and maybe pumps of the HPLC? I understand that commercial IC systems are made of mostly non-metals to avoid corrosion. (i always thought that only halides could corrode stainless steel 316).

Joe,

Relative to question one, chemical suppression is definitely not exclusive to Dionex and as you point out there are also competitive suppressor products based on electrolytic regeneration from Alltech as well (I'm not going to dwell on the strengths and weaknesses of various different designs as you sound like you have already made up your mind on your choice of suppressor. However, in my opinion, from a technical point of view, the best suppressor in both categories is produced by Dionex).

Regarding your second question, the question about whether or not carbonate/bicarbonate will result in corrosion of stainless steel tubing depends upon whether or not you will be dedicating the equipment to this purpose. Certainly carbonate/bicarbonate is not directly corrosive to stainless steel tubing which has been properly passivated. However, switching back and forth between acidic and basic eluent systems will frequently damage the passivation layer by solublizing the surface oxide components. If you are planning on dedicating a stainless steel instrument to this eluent system I doubt you would have any significant problem. However, I can tell you from actual experience on a stainless steel HPLC system that it is inadvisable to switch back and forth between alkaline and acidic eluents, especially if you are going to be analyzing compounds with any sort of chelating power (e.g. oxalic acid). Also, you need to make sure your injection valve does not have a vespel rotor seal as these can be attacked under alkaline conditions, causing column fouling.

Dear Joe,

As Chris mentioned Chemical Suppression is available from different maufacturers (e.g. Dionex, Alltech, Metrohm ...).
And I also would recommend Dionex suppression as a high ranking Dionex person.
Actually you need to make up your mind by comparing the different systems with special respect to your application.

About stainless steel and carbonate/bicarbonate eluents:
This eluent itself works perfect in stainless steel systems. But if you need to analyze e.g. phosphate, I strongly recommend to use a PEEK system. On stainless steel phosphate tends to complex on the surface as passivation goes down. This effect is faster occurring if you change eluents often.

If you are looking for a high capacity continuous chemical suppression system I would recommend a membrane based suppressor.

In anion analysis a superior alternative for regeneration of a membrane suppressor is a system based on a high molecular weight liquid ion-exchanger acid (low forbidden transport) and an external cartridge as a supply of protons. Thereby, you obtain long-term continuous suppression operation regardless of the mobile phase ion-strength. That also enables gradient elution.

Send me an e-mail if you would like more information.