Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Thoraxx on July 08, 2005, 08:57:01 PM
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I need help in determing my detection limit. Here is what I have done. I am using a Ion Chromatograph instrument to look for chloride and fluoride. I am looking for them on contact material. I have to report the results in ug/dm2. SO what I ahve done is used a dm2 amount of material and contaminated it with my test subject. Then I extracted the material in 300 mls of water and concentrated it down to 20 mls. So my final amount of sample was 20 mls.
My calibration range was 1 ppm to 25 ppm for both chloride and fluoride. So is my detection limit 20 ug/dm2 since I have 20 mls of sample?
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In analytical spectroscopy, the instrument is calibrated with a high concentration standard and a blank. The blank is measured as a test solution 3 times. The detection limit is:
DL = 3*sqroot((s1^2 + s2^2 + s3^2)/3)
where s are the stabdard deviations of the three blank replicates.
Probably, ion chromatography is something similar.