Introduction cases, the substance that is directly determined is a metal. The success of an indirect procedure greatly depends on whether 2 Discussion 2.1 Iodine species and optical details the selectivity of the reaction is maintained through (and 'in spite of ') the chemical reaction (or reactions) carried out 2.2 Atomization and procedure 2.2.1 Solvent extraction methods previously to performing the atomic absorption measurement.2,3 Since there are many factors that can affect the whole 2.2.2 Precipitation methods 2.2.3 Complexation methods procedure, indirect methods are often laborious, difficult to automatize and rarely used in routine analysis.3 On the con-2.3 Analytical figures of merit 2.4 Interferences and samplestrary, in a direct method the analyte is atomized and the absorption of radiation by its atoms is recorded to determine 3 Conclusions the analyte concentration. Thus, a direct method is usually much more simple (and much less time-consuming) as well as complexity does not prevent achieving good results and thus,