MODEL RELEASED. Precious metal analysis. Technician using a computer-aided atomic absorption (AA) spectrometer to check the metal content of various solutions. A sample (upper centre) is being introduced into the flame (not seen) of the spectrometer. AA spectroscopy is used in the detection of very small concentrations of elemental metals, for example to test the effluent from a production process or in the reclamation of metals in the recycling processes. The technique is able to detect metals at concentration levels as low as one in a million million parts.