Dear Sonja

Are you checked that all nitrate, your 10mg, are been retained initially in 
the resin?. In my experience this is the most important point, because I 
have never found problems in eluting the nitrate with the ClH. I 
periodically check the nitrate concentration in the eluted water to be sure 
that no nitrate has passed the resin. AG1X8 has high affinity for nitrate 
but other anions could be reteined too.

Rafael



Dr. Rafael Núnez Gómez
Colaborador I+D+I
Servicio de Isótopos Estables
Estación Experimental del Zaidín CSIC
Profesor Albareda 1, 18008 Granada
Spain

Tf +34958181600 Ext 228
fax +34958129600



----- Original Message ----- 
From: "Sonja Lojen" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, February 12, 2007 9:57 AM
Subject: [ISOGEOCHEM] nitrate extraction - ion exchange resin


> Dear all,
> we have problems with nitrate extraction from water for nitrogen isotope 
> analysis using ion exchange columns. We use BioRad AG1X8 ion exchange 
> resin and we don't succeed to elute the nitrate quantitatively. For a 
> water sample containing 10 mg NO3 we use 5 mL of the anion exchange resin, 
> the dripping rate is approx. 1 L/h. To elute the nitrate we use in total 
> 30 mL 3M HCl (in aliquots of 3 mL). This should be enough, but we recover 
> less than 50% NO3. What could be the problem?
>
> Many thanks for your help,
> with kind regards,
> Sonja Lojen
>
> -- 
> Doc. dr. Sonja Lojen
> Odsek za znanosti o okolju - Department of Environmental Sciences
> Institut J. Stefan - J. Stefan Institute
> Jamova 39
> 1000 Ljubljana
> Slovenia
>
> Tel.: (+386 1) 5885 393
> Fax: (+386 1) 5885 346
>