Please!! Help on ion chromatography for soil analysis

[scamiolo]

Hi guys!
I am desperate since I am trying to use an ion chromatography machine that works isocratically, in order to analyse soil extracts. I need to determine nitrate, ntrite, chloride phosphate and sulfate in the extracts. However the extracts very often are obtained shaking the soil sample with high concentrated solution (such as KCl 2M); this of course is non compatiple with IC because of the matrix effect. I know one can use also more diluite sample but still the resolution is non great. Then again the soil contains organic matter which can damage the column. What to do in order to eliminate the organic matter (is shaking with C18 particles enough?). Which are the best extraction methods for the above anions from soil, compatible with ion chromatography?
I sincerely thank anyone can give me a tip on this
cheers
Salvo

[Mark Tracy]

At http://www.dionex.com search for Application Notes AN133 and AN135. They should be a good starting point. In both cases the soil was extracted with deionized water. To remove humic acids, try the OnGuard II-P; it selectively traps polyphenolics. (I use them for cleaning up red wine.)