As per standard method, SDDC is applicable for arsenite/arsenate solutions containing maximum 20 micro gram amount. As I don't have any other choice than SDDC, I have to rely on it. Now suppose I take 35 ml as per recommendation of a sample containing 2 mg/L solution, it will be more than 20 micro gram. So I will dilute it for analysis. Suppose I take a x(>0.5) mg/L unknown & perform arsenic removal experiments, at that time I am not sure what amount might be present in a 35 ml aliquote. So SDDC most probably will not give correct result. What can be done?
Thanks!
Hi there
I am not I understand your question, but if I am right, you can pre-concentrate your sample .
I would digest let say 700mL of sample by boiling in acid (in that way all is in inorganic form), then you keep boiling to evaporate to dryness, then you reconstitute to 35mL and you have a 20 times more concentrated sample
You can of course change the amounts accordingly
Hope this helps
Actually the problem is with the "amount of arsenic" that is present in the solution. So higher concentration means in 35 ml of standard aliquote, the arsenic will be more which can cross the upper limit of 20 micro gram.
So Munoz, I have found by back calculation that a solution of 500 ppb will lead to 17.5 micro gram of arsenic in 35 ml sample. So, for 20 micro gram arsenic amount, the maximum concentration of intial solution will be (20/35) ug/ml = 0.5714 ug/mL or 571.4 ug/L.
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