Development of variance-filtered instrumental transfer methods for high-resolution NMR spectroscopy

The introduction of a variance-filter to both direct standardization (DS) and piece-wise direct standardization (PDS) instrumental transfer methods for the analysis of NMR spectral data is described. The variance-filter modification allows for the identification of regions in the NMR spectra that are not adequately represented by the limited number of transfer calibration samples used during the calculation of the instrument-to-instrument transfer matrix. For these spectral frequencies, the corresponding portion of the transfer matrix is replaced by identity (or scaled identity) prior to the secondary instrumental data sets being transferred to the target instrument response. The spectral matching performance of the variance-filtered instrumental transfer method as applied to high-resolution (1)H NMR spectra is presented along with possible uses and limitations. Copyright (C) 2010 John Wiley & Sons, Ltd.