Multicommutation in flow analysis part. 1. Binary sampling: concepts, instrumentation and spectrophotometric determination of iron in plant digests - Reis, Boaventura Freire dos; Giné-Rosias, Maria Fernanda Georgina; Zagatto, Elias Ayres Guidetti; Lima, J. L. F. C.; Lapa, R A (Analytica Chimica Acta, 1994)