Discussion Category:  Atomic Absorption

"AAS iCE 3000 Series Chromium content less absorption”

We are using above mentioned Flame AAS in our laboratory. We are analyzing in chromium content using Acetylene and Nitrous oxide gas absorption level is very less. Normally 0.4 absorption in 5 ppm but we are getting only 0.045 absorbance level. We are checking with standard solution the standards are no deviation. we are consulting with service person they told Nitrous oxide and Acetylene gas combination flame will be a "Red cone formation". But we are getting blue mixed with yellow colour.This is the reason for lesser absorbance or any other reason. Please help me.

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Asked by

Harun
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Dim

Dear Harun,

For 5ppm you will get 0,4 absorption units, only if you have optimized your method.  What is written in the cook book works only under perfect conditions. When working with nitrous oxide you should first let your burner work with air/acetylene for 30 minutes and then change the gas. Let your lamp on for 30 min. also. Check the burner height and orientation, and then the nebulizer flow. Start with standards first. If your standards are OK then you have problem with your sample. Sometimes the nebulizer tube gets clogged and needs cleaning or replacement. The flame should be as you describe. It gets red when sample gets burnt.

I hope this helps.

D

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Harun

Dear Dim,

Thank you for your help.I will follow your instructions.

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