Yl. Xie et al., ASSESSMENT OF PEAK PURITY IN LIQUID-CHROMATOGRAPHY USING CONDITION INDEX AND SINGULAR-VALUE EVOLVING PROFILES, Analytica chimica acta, 317(1-3), 1995, pp. 17-32
A new method for peak purity control in liquid chromatography with dio
de array detection is proposed, based on both the concept of condition
index evolving profiles (CIEPs) and singular value evolving profiles
(SVEPs) and the technique of moving fixed-size window along the chroma
tographic retention time axis. The CIEPs and SVEPs are produced by sin
gular value decomposition (SVD) on data matrices constrained by the mo
ving window which contains a fixed number of spectra and moves along t
he chromatographic profile. Visual inspection of the singular values a
nd condition indices, as they evolve along the chromatographic retenti
on time, enable to detect small amounts of a spectrally similar impuri
ty under a major peak with zero chromatographic resolution. No assumpt
ions are made about the shape of the spectra of the compounds involved
or about the degree of spectral similarity of the major compound and
the impurities. The method was checked using simulated experiments.