Following the evolution of plants (their growth, nutrient deÐciency, food value etc.) requires the determination of their elemental contents. One needs to determine the chemical composition of plants in order to estimate their impact on biomass burning emissions, one of the most important sources of atmospheric pollution, especially in the tropics. To obtain the multi-element composition of plant samples, a procedure using x-ray Ñuorescence spectrometry was developed. The matrix e †ects a †ecting the relationship measured intensities concentrations were cor-¿s. rected by the scattered radiation method. Specimen preparation requires only 300 mg of dried and Ðnely ground material for the simultaneous determination of Na, Mg, P, S, Cl, K, Ca, Mn and Fe in reference materials and in savannah grasses (the samples of interest). The whole experimental procedure is carried out in less than 5 min. The main advantage of the method is the non-modiÐcation of the original sample, either during specimen preparation or in the exciting x-ray beam. Therefore, storage and complementary analyses of the prepared specimens are possible. For savannah grasses, which can contain relatively high concentrations of silica, Si has also been determined, but by means of a glass-disc preparation from 100 mg of sample powder.