Mode of Operation
Most currently available GFAAs are fully controlled from a personal computer that has Windows-compatible software. Aqueous samples should be acidified (typically with nitric acid, HNO3) to a pH of 2.0 or less. Discoloration in a sample may indicate that metals are present in the sample. For example, a greenish color may indicate a high nickel content, or a bluish color may indicate a high copper content. A good rule to follow is to analyze clear (relatively dilute) samples first, and then analyze colored (relatively concentrated) samples. It may be necessary to dilute highly colored samples before they are analyzed. They are more sensitive than flame atomic absorption spectrometers. After the instrument has warmed up and been calibrated, a small aliquot (usually less than 100 microliters (µL) and typically 20 µL) is placed, either manually or through an automated sampler, into the opening in the graphite tube. The sample is vaporized in the heated graphite tube; the amount of light energy absorbed in the vapor is proportional to atomic concentrations. Analysis of each sample takes from 1 to 5 minutes, and the results for a sample is the average of triplicate analysis.
Read more about this topic: Graphite Furnace Atomic Absorption
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