I am learning to measure on a flame photometer JENWAY. The instructions say that after setting the blank sample (readout = 0), a standard solution with a higher concentration than the expected concentration in the sample is sucked in. I quote:
“Aspire a standard solution of slightly higher concentration than expected in the samples to be tested. Adjust the fine and coarse control until a positive reading is obtained. This is a nominal value to be used in optimising flame conditions.”
My question is: How do I find the nominal values for individual elements (Na, K, Ca, Li, Ba)?
Please, can someone give me an advice or recommend me professional literature where I could find them? thank you very much.
Thanks for your question! What you wrote is correct. In order to calibrate a photometer, you enter the known conctrations of elements of the standard solutions. Then, once the calibration curve has been plotted, the readings for the sample solutions are compared with the curve to allow the sample concentrations to be established.
The reason for apsiring a solution of slightly higher concentration than expected in the samples to be tested is related with the sensitivity and accuracy of the measurment.
**Since flame photometers rely on the emission of light from excited atoms in the flame to measure the concentration of specific elements, by aspirating a standard solution with a higher concentration of the element of interest, you ensure that the signal is strong enough to be easily detected and measured. Secondly, if you would aspirate a blank solution with zero concentration (i.e just the solvent), you set the instrument’s baseline or “readout” to zero. Instead, by aspirating a higher concentration standard, you can adjust the baseline to a positive value. This adjustment allows the instrument to measure positive concentrations accurately and provides a better reference point for subsequent sample measurements. **