  The resolution and calibration of pure spectra of minority components in
measurements of chemical mixtures without prior knowledge of the mixture is a
challenging problem. In this work, a combination of band target entropy
minimization (BTEM) and target partial least squares (T-PLS) was used to obtain
estimates for single pure component spectra and to calibrate those estimates in
a true, one-at-a-time fashion. This approach allows for minor components to be
targeted and their relative amounts estimated in the presence of other varying
components in spectral data. The use of T-PLS estimation is an improvement to
the BTEM method because it overcomes the need to identify all of the pure
components prior to estimation. Estimated amounts from this combination were
found to be similar to those obtained from a standard method, multivariate
curve resolution-alternating least squares (MCR-ALS), on a simple, three
component mixture dataset. Studies from two experimental datasets demonstrate
where the combination of BTEM and T-PLS could model the pure component spectra
and obtain concentration profiles of minor components but MCR-ALS could not.
