I am learning about different analytical methods such as Atomic Absorption Spectrscopy and Atomic Emission Spectroscopy and I'm having a difficult time understand how to interpret the detection limits for the different methods. For example, for AES my book says "detection limits when using an ICP are significantly better than those obtained with flame emission" follow by the table below.

I understand that the detection limit shows the lowest quantity of an element that can be detected by the instrument. However, how do I choose which is the better instrument for an experiment? And why is "ICP significantly better than flame emission"? I would assume that the larger the detection limit, the better since you have a greater limit and thus a better chance of detecting the element. Is that not the correct way to think?

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That is NOT the correct way to think. The lower the detection limit of a method, the easier it is to detect the material. For example, from the data in the table, you would be able to detect 0.2 ug/ml of Ag using ICP, but only 2 ug/ml using flame emission. So, if your sample had less than 2 ug/ml and you were using flame emission, you would not be able to reliably detect the Ag in that sample. Make sense?

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  • $\begingroup$ Oh okay, so if I didn't know the amount Ag in my sample I would choose ICP because it would allow to measure even the smallest amount of Ag in my sample but if I knew that my sample contained more than 2ug/ml then I could use flame emission. $\endgroup$ – J.Se May 21 '18 at 11:01
  • $\begingroup$ Yes. That is the correct way to look at it. $\endgroup$ – Dr. J. May 21 '18 at 11:44

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