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Deformed peaks and Wastewater determination by IC?
Posted: Fri May 11, 2018 3:19 pm
by iperdomo
Hello! According to Standard Methods is posible to determinate anions by IC on Wastewater, but this kind of matrix content high concentrations,
1. Isn't it gonna saturate the column faster?
2. What is approximatly the highest limit for concentrations determined by IC?
3. Is it ok if I construct a calibration curve in a range of 100 to 500 mg/L for Sulfate in wastewater?
Also, I'm facing a trouble with Sulfate peaks, my suppressor isn't working well, the catridge is expelling regenerant solution,
4. Is this the reason why peaks are looking deformed?
5. Is it due to high concentrations? Or otherwise what migh be the reason?
As always, thank you so much for your help.
Re: Deformed peaks and Wastewater determination by IC?
Posted: Wed May 16, 2018 12:45 pm
by Khanom
Dear iperdomo,
I am sorry, but I was not able to visualise an image.
1 I am unaware of the type of waste water you are sampling. It is possible to clean up the matrix using solid phase extraction (SPE) prior to injection onto the IC system, or even dilute with IC grade water. Do you use a guard column?
2 You should be able to determine the lower concentrations of say 1 mg/L (1 ppm), with ease.
3 As we both do not know the amounts of sulphate present, you may have to first use a linear calibration curve with a large concentration range. When you have an approximate idea of sulphate concentration, you may then use a more finely tuned linear calibration curve, with a more narrow concentration range, which encompasses the approximate concentration of the sulphate found.
If your anion suppressor is not performing correctly, then you will have to repair it or not use it. As you are probably looking at high concentrations of anions, a suppressor may not be required. There are anion IC methods, where a mobile phase of 4 mM p-Hydroxybenzoic acid, 2.5%methanol, 0.1 mM sodium thiocyante pH 8.5, may be used, without a suppressor.
4 I cannot see an image, therefore cannot comment.
Re: Deformed peaks and Wastewater determination by IC?
Posted: Wed May 23, 2018 9:11 am
by Markus Laeubli, Metrohm
Dear iperdomo
Wastewater samples typically need some sample preparation steps. Typically dilution and filtration.
I would recommend to dilute in minimum by a factor of 10. Then you might be in a concentration range where oalso high sulfate concentrations are handled correctly.
If you need to calibrate over a high concentration range we recommend to use multiple calibration curve segments. This imporved the accurracy of the results over the full range.
Also for dilution and filtration we recommend to apply Inline Sample Preparation method.
Best regards