Experiment 30 Verifying Optimum Instrument Parameters for Flame AA

Experiment 30 Verifying Optimum Instrument Parameters for Flame AA 

Prepare a standard solution of a metal by diluting a stock standard with water to give a concentration that will give a reasonable absorbance when conditions are optimal, such as 5 ppm copper or zinc. Your instructor may have a suggestion for which metal and what concentration. 

Lamp alignment. Vary the position of the lamp alignment screws, both the vertical and the horizontal, individually, half a turn in each direction from the optimum and record the absorbance with each half turn. After recording the data for one, either the vertical or the horizontal, reset to the optimum then vary the other. This will result in two sets of data, one for the vertical and one for the horizontal with different absorbance values recorded for each half turn away from the optimum in both directions. 

Fuel flow rate. Your instructor will show you how to vary the fuel flow rate to the burner head and also how to read the flow rate on the flow meter. Measure absorbance values at ten different flow rates, selecting a flow rate range that will maintain a flame while bracketing what the manufacturer s literature or your instructor may suggest as the optimum. 

Oxidant flow rate. Repeat the above, but for the oxidant flow rate rather than the fuel flow rate. Use extreme caution here, since a flashback may result from too much or too little oxidant flow. 

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