Near-IR Calibration Transfer between Different Temperatures

Abstract

Calibration transfer between spectra measured at different temperatures was investigated for near-IR spectroscopic determination of NaCl in aqueous solutions. A principal component regression (PCR) calibration model developed at 23.0 C was transferred to 28.5 C by using a piecewise direct standardization (PDS) method. The effect of window symmetry on calibration transfer was investigated. Only two transfer samples were needed in obtaining a good calibration transfer. The standard error of prediction (SEP) was 0.048 M NaCl when the calibration model developed at 23.0 C was used for predictions at 28.5 C without the standardization. The SEP was reduced to 0.008 M through the standardization, which was very close to 0.006 M obtained from a full set recalibration at 28.5 C and 0.007 M obtained from a general calibration model based on the spectra measured at different temperatures between 23.0 and 28.5 C. The calibration transfer from one temperature to another can save a lot of time in remeasuring the calibration samples and redeveloping a new calibration model at a new temperature.