Standardization from a benchtop to a handheld NIR spectrometer using mathematically mixed NIR spectra to determine...

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Chemometrics

Background:

• Field measurements using portable instruments are increasingly important.
• Calibration transfer techniques allow models from benchtop instruments to be used with portable ones, saving time and cost.
• Traditional methods require physical transfer samples, which can be unstable.

Purpose of the Study:

• To evaluate virtual standards for calibration transfer using the reverse standardization (RS) method.
• To standardize spectral data from dissimilar fuel samples (gasoline, biodiesel blends) between a benchtop and a portable NIR spectrometer.
• To avoid issues associated with physical transfer samples like volatilization and composition changes.

Main Methods:

• Virtual standards were created by mathematically mixing spectra of pure solvents.
• Reverse standardization (RS) was applied to transfer calibration models.
• Partial least squares regression (PLS) models were built for fuel quality parameters.

Main Results:

• Standardization using virtual standards yielded RMSEP values comparable to reference method reproducibility for most parameters.
• The RS procedure successfully transferred spectral data between dissimilar spectrometers.
• Deviations were noted for density and biodiesel content when using virtual samples.

Conclusions:

• The use of virtual standards with the RS method is a promising approach for calibration transfer between benchtop and portable NIR spectrometers.
• This technique facilitates the use of robust benchtop models on portable devices for fuel analysis.
• Virtual standards offer a viable alternative to physical transfer samples, simplifying field measurements.