A　new　method　which　combines　Fourier-transform　smoothing　with　ratio　spectra　derivative　spectrophotometry　has　been　developed　for　analysis　of　binary　and　ternary　mixtures.　The　method　proposed　has　been　applied　to　the　simultaneous　determination　of　a　binary　mixture　of　0.974-2.026　×　10-2gL-1　nitrate　and　nitrite　and　to　a　ternary　mixture　of　1.840-3.888　×　10-3　g　L-1　histidine,　phenylalanine,　and　tryptophan.　The　relative　standard　derivations　are　between　0.07　and　5.3%　for　the　former　system,　and　between　0.5　and　7.3%　for　the　latter.　The　results　show　that　the　method　proposed　is　more　accurate　than　multiple　linear　regression.　©　Springer-Verlag　2001.