Calibration Curve for ICS DIONEX-1000

Basic questions from students; resources for projects and reports.

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Hello to all,
I have a problem about the building of anionic calibration curve by Chromeleon 6.7. I need a linear curve with external standards.
My operations are: Preparation of 3 known concentrations from stock solution. The stock standard solution (ThermoFisher) contains 7 anion (Fluoride 20mg/L, Bromide 100mg/L, Chloride 100mg/L, Nitrite 100mg/L, Nitrate 100mg/L, Phosphate 200mg/L and Sulfate 100mg/L). So, I preparare 3 dilutions from this standard solution 1:1, 1:5, 1:10 (500um stock + 500um water; 1ml stock + 4 ml water; 1ml stock + 9ml water). After that, I inject to obtain the runs, I create my Peak Table where I name the seven peaks and I add amounts in the three coloumns. The integration is set to the disabilitation of Negative Peak. At this level, I obtain my curve where only the solution 1:1 is on the line, but the other two are outliers, why? If it's useful to know, the eluent is 9mM Na2CO3.
Can someone help me to understand my mistakes? Please, thank you!
Is this topic still relevant to you?

For what analytes is your three-point calibration out of range?
If this is the case for all analytes I would expect a systematic error, although it is difficult to tell you were it comes from. You did not specify, so I just assume you used miliQ-Water for the sample preparation step?
Some wild guesses for other reasons: pH of the samples is too different, the system is not equilibrated, problems with integration, just to name a few...
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