A number of technologies exist that can be used to separate the polychromatic NIR spectral region
into monochromatic frequencies for both qualitative and quantitative purposes. Broadband, discrete
filter photometers, or light-emitting diode (LED) based instruments provide spectral coverage over a
narrow spectral region (50–100 nm). Diffraction grating, interferometer, diode-array or acousto-optic
tunable filter (AOTF) based instruments provide full-spectral coverage. Selection of the appropriate
technology is usually based upon the required analyte sensitivity and selectivity, reliability, ease-ofuse,
and implementation needs. Furthermore, pharmaceutical and chemical manufacturers demand
cost-effective and efficient method development and implementation.
NIRS XDS analyzers use a combination of internal performance standards to maintain instrument
stability and response and NIST-traceable external standards placed directly at the sample location to
precisely match the band pass, photometric and wavelength response for all analyzers at the sample
location. By precisely matching the performance for all instruments, a quantitative calibration model
or a qualitative library developed on one XDS NIR analyzer can be used to predict quantitative or
qualitative results on subsequent analyzers (of similar configuration) or the same analyzer after service
(lamp or component change) without requiring a bias or slope adjustment or any other data
manipulation.