In situ determination of K, CA, S and SI in fresh sugar cane leaves by handheld energy dispersive x-ray fluorescence spectrometry - Guerra, Marcelo Braga Bueno; Adame, Andressa; Almeida, Eduardo de; Brasil, Marcos Augusto Stolf; Schaefer, Carlos Ernesto Gonçalves Reynaud; Krug, Francisco José (Journal of the Brazilian Chemical Society, 2018)