Chromatography Forum

Hello,

Is it possible to analyze chemically digested nitrogen samples with IC? Our laboratory uses chemical digestion to oxidize total nitrogen in water samples into nitrate. Currently we use FIA to measure the nitrate concentration after digestion but we are considering purchasing an IC instrument. We would like to find out if we are able to measure total nitrogen (TKN, total Kjeldahl nitrogen) using a combination of chemical digestion and IC.

For digestion we use a mixture of potassium peroxosulphate, sodium hydroxide and boric acid. Do IC instruments tolerate this kind of strong reagents?

Greetings from Finland,

Raija.

Dear LVT;
I am Happy to see someone is trying to do this; I use to analyze TN from pond in an shrimfarm a couple of year ago; I did not have an IC so I implemented Ion Pair method using C18; and detecting with UV; it was good even when I see a BIG peak form Sulphete. I do not see any problem runing with IC, I think metrhom have a similar aplication; but rebember probably you will have to neutralize your sample befor put it into the column.

Regards form Costa Rica.

Why do you want to change from FIA? It is certainly possible to analyze nitrate using IC, but will probably be more trouble than using an automated colorimetric method. You might want to look into discrete analyzers. We have a Seal AQ2 for nitrate, phosphate, and ammonia analysis. It operates on the same principal as FIA, but generates far less waste and is less messy than our old lachat.

The application will be possible with IC after neutralization. Metrohm wis able to do all th required Sample Prep step automatically.
For details check with your local Metrohm distributor.

Yes Nitrate can be analysed by IC.

Are you running Kjeldahl ? If so why not look at alternatives. Thermo offer the HiPerTOC for TOC and TN on liquids and solids and Flash for Dumas combustion for Nitrogen. Why use Kjeldahl at all ? These techniques solve your disposal problems and are much faster.