Comparison of two multiplicative signal correction strategies for calibration transfer without standards

Two multiplicative signal correction (MSC) algorithms are compared for the standardization of data from two near-infrared (NIR) spectrometers. Absorbance spectra were measured from 1000-2200 nm for a set of 45 jet fuel samples. Data from one instrument were standardized to match data from a second instrument using windowed MSC (W-MSC) and moving window MSC (MW-MSC). For W-MSC user-defined windows were selected and for MW-MSC the window size was optimized based on a two-step procedure: 1) assigning a cut off window to avoid over-processing and 2) selection of a specific window size based on sample leverage. For reproducibility studies performed over time on a single instrument, data extending through the last day of the study (63 days outside the calibration) required no preprocessing except a peak alignment correction on day 58. For analysis between the two instruments, successful results were obtained using a sub-region of the data from 1000–1700 nm processed by MW-MSC using a 441 point window. A method of selecting an appropriate window size is proposed based on statistical significance testing.