Hi every body
I am using ion chromatography for analysis of water samples. these samples are surface water.
I got the concentration of anion ( NO3, Cl, SO4) and Cations ( Na, Ca, Mg, K).
Then I Did titration for CO3 and HCO3 .
Summation of total Anions and Cations is not equal and I got error[ ( Sum anions-Sum cations/ sum anions +sum cations) *100 ] more than 2% even 5%.
my question is about this error. Is this error is correct? I mean this error can be one solution for Data accuracy from chromatography. If not correct, how can I confirmation of data? from chromatography. If not correct, how can I confirmation of data?
If this difference in the ion balance is reproducible and systematic, and at your level the sum of the basic ion concentrations is unacceptable and you are sure that the samples do not yet contain other ionic components (e.g. their pH is significantly different from pH 7 or contain e.g. a lot of strontium, etc.) then first use some reference materials similar in composition to your samples to make sure you really have a problem.
If your results are confirmed to be inaccurate, verify that your calibration solutions are accurate by comparing them with other calibration solutions, your own or someone else's. Maybe also with the use of a different measuring instrument, a different measuring technique, in a different laboratory.
ZJ
You may need to consider the Uncertainty of Measurement of each method. There are numerous texts and websites that can assist you in calculating these values. My feeling is that your values are not significantly different, and each of the measurement uncertainties is contributing to the overall error.
What sort of concentrations are you measuring? If you are working in low mg/L range (parts per million), then perhaps a 2-5% error is fine. If your samples are in the grams per litre range, then maybe 2% is way too much.
You could try some mixed solutions with anions that you have prepared yourself. See how different methods work for the same mixture. I suspect you will not get exactly the same value from the two techniques.
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