ARTIFACTS IN EVOLVING FACTOR ANALYSIS-BASED METHODS FOR PEAK PURITY CONTROL IN LIQUID-CHROMATOGRAPHY WITH DIODE-ARRAY DETECTION

Evolving factor analysis and related techniques are promising methods for peak purity control in liquid chromatography with photodiode-array detection (DAD). Practical application of these techniques, however, can be limited by instrumental and experimental non-idealities. Possible reasons include a non-zero or sloping baseline, the DAD scan time, calibration graph non-linearity and heteroscedasticity. Methods are presented for correction of the first two problems. As various instruments behave differently, it is likely that the relevant difficulties depend on the instrument used. Additionally, one has to take into account that mobile phase effects, leading to changes in the spectra, are a potential source of artefacts. The detection limit of an impurity as a function of chromatographic separation, relative concentration and amount of noise was also studied for simulated data.