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.