The First Key Comparison of Primary Standard Gas Mixture of the Brazilian National Metrology Institute A.L. Fioravante, C. R. Augusto, E.C.S. Elias, M.C. Brum, D.C.G.S. Teixeira, C.C. Ribeiro, R.J. Oudwater, F.A. Fagundes, M.C. da Silva and R.G. Reis Published online: 07 October 2013 DOI: 10.1051/metrology/201310006