Chemometric selection of a small set of pharmaceutical active substances used in determining the orthogonality and similarity of chromatographic systems

A set of 68 active pharmaceutical substances (mainly basic, but also some neutral and acidic) was earlier used to determine the orthogonality/similarity of chromatographic systems. The orthogonality of the systems was evaluated from correlation coefficients-based weighted-average-linkage (WAL) dendrograms and color maps. To increase the throughput in assessing systems, a representative subset of substances that leads to analogous conclusions about orthogonality/similarity was selected. Both the Kennard and Stone (K&S) algorithm applied on the autoscaled principal component analysis data from the Weighted Holistic Invariant Molecular (WHIM) descriptors of the test molecules, and WAL dendrograms on retention data were used for that purpose. A subset of 10 substances was found to give similar conclusions about orthogonality and similarity of the systems examined.