 |
|
| Science Forum Index » Chemistry Forum » preparation of water samples for ionic chromatography... |
|
Page 1 of 1 |
|
| Author |
Message |
| Ay... |
 Posted: Fri Oct 16, 2009 3:10 am |
|
|
|
Guest
|
Hello everybody,
I have some questions about ionic chromatography.
In bibliography and books, I read that it is necessary to use HNO3 to
acidify water samples using ionic chromatography.
I understand that it improves conservation of samples but I don't
understand well how it works chemically. Can you explain me in
details ?
In european standards, acidification with HNO3 is used only for
cation
analysis not for anion analysis. I don't understand why we need to
acidify for cation and not for anion. Especially that I'm using a
HSO4
eluent (in cation chromatography). In anion chromatography, i'm
working with KOH eluent.
At what time is it better to acidify? At sampling or only in
laboratory?
In which concentration/amount have I to acidify my samples?
When I have only one sample for anion and cation analysis, does it
matter if the sample is acidified for the anion analysis? I think it
does because we have more NO3- in solution. Then, in this case, how
to
proceed ?
I really want to understand every step of analysis, that's why I'm
asking all these questions.
Thank you for your help ! |
|
|
| Back to top |
|
|
|
| Bill Penrose... |
| Posted: Fri Oct 16, 2009 8:28 pm |
|
|
|
Guest
|
On Oct 16, 6:10 am, Ay <ay.duf... at (no spam) gmail.com> wrote:
[quote:9608cade35]I have some questions about ionic chromatography.
In bibliography and books, I read that it is necessary to use HNO3 to
acidify water samples using ionic chromatography.
[/quote:9608cade35]
1. Decomposes ion pairs (eg, CaPO4-1) and prevents postprecipitation
of magnesium and calcium salts, as phosphates or carbonates, etc.
2. Prevents growth of molds, algaes, etc.
3. Nitric acid won't precipitate with any imaginable anions. (So add
it at the time of sampling.)
DB |
|
|
| Back to top |
|
|
|
| Bolaleman... |
| Posted: Sat Oct 17, 2009 11:34 am |
|
|
|
Guest
|
On 16 oct, 09:10, Ay <ay.duf... at (no spam) gmail.com> wrote:
[quote:d0a9df0a31]Hello everybody,
I have some questions about ionic chromatography.
In bibliography and books, I read that it is necessary to use HNO3 to
acidify water samples using ionic chromatography.
I understand that it improves conservation of samples but I don't
understand well how it works chemically. Can you explain me in
details ?
In european standards, acidification with HNO3 is used only for
cation
analysis not for anion analysis. I don't understand why we need to
acidify for cation and not for anion. Especially that I'm using a
HSO4
eluent (in cation chromatography). In anion chromatography, i'm
working with KOH eluent.
At what time is it better to acidify? At sampling or only in
laboratory?
In which concentration/amount have I to acidify my samples?
When I have only one sample for anion and cation analysis, does it
matter if the sample is acidified for the anion analysis? I think it
does because we have more NO3- in solution. Then, in this case, how
to
proceed ?
I really want to understand every step of analysis, that's why I'm
asking all these questions.
Thank you for your help !
[/quote:d0a9df0a31]
i worked quite a bit with a dionex and never added HNO3 to the eluent.
In particular when you are analyzing nitrate you should avoid any
contamination of the sample with this ion. |
|
|
| Back to top |
|
|
|
| Ay... |
| Posted: Mon Oct 19, 2009 2:32 am |
|
|
|
Guest
|
On 17 oct, 08:28, Bill Penrose <dangerousb... at (no spam) gmail.com> wrote:
[quote]On Oct 16, 6:10 am, Ay <ay.duf... at (no spam) gmail.com> wrote:
I have some questions about ionic chromatography.
In bibliography and books, I read that it is necessary to use HNO3 to
acidify water samples using ionic chromatography.
1. Decomposes ion pairs (eg, CaPO4-1) and prevents postprecipitation
of magnesium and calcium salts, as phosphates or carbonates, etc.
2. Prevents growth of molds, algaes, etc.
3. Nitric acid won't precipitate with any imaginable anions. (So add
it at the time of sampling.)
DB
[/quote]
Thank you very much for your complete answer.
If I understand well, there is no problem in acidifying samples (even
for anion anlysis), at the sampling step, unless I have to analyse
nitrate ion.
So I think it's ok if I put 1mL of HNO3 (1mol/L) in my mother solution
of ion and the same volume of HNO3 in my samples/standards.
Again thank you for your answer, it's all clear now !
Ay |
|
|
| Back to top |
|
|
|
| Ay... |
| Posted: Mon Oct 19, 2009 2:38 am |
|
|
|
Guest
|
On 17 oct, 23:34, Bolaleman <oswald_epp... at (no spam) hotmail.com> wrote:
[quote]On 16 oct, 09:10, Ay <ay.duf... at (no spam) gmail.com> wrote:
Hello everybody,
I have some questions about ionic chromatography.
In bibliography and books, I read that it is necessary to use HNO3 to
acidify water samples using ionic chromatography.
I understand that it improves conservation of samples but I don't
understand well how it works chemically. Can you explain me in
details ?
In european standards, acidification with HNO3 is used only for
cation
analysis not for anion analysis. I don't understand why we need to
acidify for cation and not for anion. Especially that I'm using a
HSO4
eluent (in cation chromatography). In anion chromatography, i'm
working with KOH eluent.
At what time is it better to acidify? At sampling or only in
laboratory?
In which concentration/amount have I to acidify my samples?
When I have only one sample for anion and cation analysis, does it
matter if the sample is acidified for the anion analysis? I think it
does because we have more NO3- in solution. Then, in this case, how
to
proceed ?
I really want to understand every step of analysis, that's why I'm
asking all these questions.
Thank you for your help !
i worked quite a bit with a dionex and never added HNO3 to the eluent.
In particular when you are analyzing nitrate you should avoid any
contamination of the sample with this ion.- Masquer le texte des messages précédents -
- Afficher le texte des messages précédents -
[/quote]
Thank you for your answer.
I don't add HNO3 in my eluent (I work on a Dionex too and my eluent is
H2SO4 18mM). I was wondering how using HNO3 in my samples and my
standards solution to avoid contamination.
I think it doesn't matter for cation AND anion analysis if I add it in
my samples, unless I have to analyse nitrate amount (logical because
of NO3- ions). |
|
|
| Back to top |
|
|
|
|
|
All times are GMT - 5 Hours
The time now is Fri Dec 11, 2009 2:29 pm
|
|