Calibration of gas chromatography mass spectrometry of two-component mixtures using univariate regression and two- and three-way partial least squares

Univariate calibration and two-way and three-way partial least squares (PLS) were applied to a series of GC-MS results for 21 mixtures of two closely eluting compounds, salbutamol and clenbuterol, Steps in the analysis, including baseline correction, alignment of chromatograms, mass selection, unfolding (for three-way data), standardizing and centring, are described, appropriately modified for the problem in hand, Both mass spectral and, for three-way data, time dependent loadings can be calculated, The quality of quantitative predictions was determined using a leave one out cross validation method, For PLS slightly better predictions were obtained compared with the best predictions for univariate single ion monitoring, Three-way PLS provides a wealth of extra information.