Qualitative and Multi-Element Quantitative Flame-Emission Analysis of Group IA and Group IIa Elements Using a Flame Photometer, a Fiber-Optic Probe, and a Spectrometer

This manuscript describes the use of a flame photometer, a fiber-optic probe, and a spectrometer to reliably record the emission spectra (wavelength and intensity) of Li+, Na+, K+, Ca2+, and Sr2+ solutions. The setup removes the problems of transient short-lived emissions observed with Bunsen burner flames. Students are able to establish the uniqueness of each element’s emission spectra as well as determine the concentrations of all five metal ions in a single sample. Because the third most intense Sr2+ peak at 670.3 nm matches the Li+ single emission, students perform two different procedures in order to determine Li+ in the presence of Sr2+. In one procedure, the intensity expected from the Sr2+ is subtracted and in the other procedure the Sr2+ is precipitated as SrSO4 using Fe(II)(NH4)2(SO4)2·6H2O (s). We also have students determine the concentrations of these ions in Gatorade.