with elements my given and need to obtain the unknowns X(l)„ Y(l);, X(2);, Y(2) y . This can be compared to a system with one equation and four unknowns. Algebraically speaking, there is no exact solution to such a system. In fact, there are an infinite number of solutions. Clearly, this is not a trivial mathematical problem. However, it was shown that by using certain well-known properties of fluorescence and the fact that the solutions should be nonnegative, a unique solution to Equation 2 for a binary mixture can oftentimes be obtained. This was accomplished by rotation of the eigenvectors of MM' and M f M to nonnegative basis vectors (possible spectral vectors). In other cases where ambiguity exists, a priori knowledge of spectral overlap will decrease or eliminate the ambiguity. The second paper published was indeed a curve fitting approach. However, there was one point of disagreement with Talmi et al. This work showed that when all components are not specified, a nonnegative residual approach such as linear programming is superior to a least-squares approach. Finally, Talmi et al. also pointed out some of the advantages of acquiring data with a video fluorometer. However, they further stated that the same data can be acquired in a " . . . slower but more accurate and simpler manner" using electromechanical scanning methods. They neglected to point out the obvious advantage of the video fluorometer over these slower methods. For example, valuable kinetic information can be obtained by simultaneously monitoring luminescing species in a chemical reaction. A time resolution of milliseconds or a few tenths of seconds would certainly be more useful than the minutes or hours required for electromechanical methods. Consequently, this kinetic information is acquired most effectively with a video fluorometer. Isiah M. Warner Department of Chemistry Texas A&M University College Station, Tex. 77843 Contributions from readers are invited for the LETTERS section. Topics should preferably be of broad interest to readers and/or may be comments on material published in the A-pages. See Prof. Laitinen's editorial, page 1281, August 1977.
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UNITED SCIENTIFIC ANALYTICAL INSTRUMENTS DIVISION CIRCLE 211 O N READER SERVICE CARD
ANALYTICAL CHEMISTRY, VOL. 51, NO. 1, JANUARY 1979 · 21 A
