Improvement in Fourier Near- and Mid-Infrared Diffuse Reflectance Spectroscopic Calibrations through the Use of a Sample Transport Device

Abstract

The objective of this research was to determine whether diffuse reflectance calibrations using a Fourier transform spectrometer (FTS) could be improved by increasing the scanned sample area. A linear motion sample transport (TRANSCELL) was attached to the FTS, which increased the area scanned from 2 mm in diameter (stationary cell or STATCELL) to 2 × 50 mm. Sodium chlorite-treated forages and by-products ( N = 174) were scanned in the near-infrared (NIR) and mid-infrared (MIR) with the use of the TRANSCELL and STATCELL. Samples were analyzed for fiber, digestibility, lignin, protein, and lignin nitrobenzene oxidation products (NOPs). Overall, the best results for fiber, lignin, and digestibility were achieved by using MIR spectra and the TRANSCELL. Results in the NIR (FTS) with the use of the TRANSCELL were also improved over those obtained with the STATCELL. While the TRANSCELL was an improvement over the STATCELL for Fourier NIR analysis of NOPs, in the MIR, results for NOPs were about equal for the TRANSCELL and STATCELL. In conclusion, the use of a TRANSCELL can improve calibrations from Fourier transform spectrometers, although the degree of improvement depends on the spectral region and specific calibration under study.