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Topic: Spectrometry  (Read 4434 times)

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creek

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Spectrometry
« on: September 28, 2004, 03:20:13 AM »
Hello everyone,

I am a non chemistry guy, but I have stumbled upon a problem about spectrometry. What I want to understand is where does the equation

Intensity = concentration * factor

comes about. What is the intensity conc. and the factor in the above.

Also if there are other elements involved say if we looking at steel, and we are trying to determine the actual concentration of zn in the steel sample, and for arguments sake it contains traces of Ni and Cu along with Fe ofcourse. All these will show up in the spectrum and interfere in the equation. How do we set up the equation in this case, and I believe they have to be set up as matrices, Can anyone explain or make reference so that I can understand.

Many thanks,

P.S. I understand my question might not be as clear, I will try to clarify myself if you have difficulties.

Offline AWK

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Re:Spectrometry
« Reply #1 on: September 28, 2004, 05:19:55 AM »
Read on Lamber-Beer law
AWK

Demotivator

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Re:Spectrometry
« Reply #2 on: September 28, 2004, 09:35:42 AM »
What type of spectrometry? Atomic absorption or emission?
Anyway the instrument is adjusted to focus in on a characteristic wavelength that is appropriate for the element being analyzed. So even if there are other elements they would theoretically not be sensitive or respond to that wavelength. The interferences may, however, make some contribution to the background levels and make minor contributions to the intensity (called a matrix effect). To guard against that, the standards for the element being analyzed are prepared to include the other elements in proportions about the same as the sample. That is called the standard's matrix.

Intensity = concentration * factor
The factor is just a proportionality constant that is different for different elements. It's just the slope of the straight line you get when plotting Intensity vs conc of the standards. The conc of the sample is determined by where the sample intensity falls on that line.



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