Evaluation of basic algorithms for transferring quantitative multivariate calibrations between scanning grating and...

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Pharmaceutical Analysis

Background:

• Instrument-to-instrument calibration transfer is a significant challenge in near-infrared spectroscopy (NIR).
• Selecting appropriate calibration transfer methods is often complex.
• Quantitative calibrations developed on one NIR instrument may not perform reliably on others.

Purpose of the Study:

• To evaluate various methods for transferring quantitative NIR calibrations between different instruments.
• To assess the impact of different instruments and transfer techniques on prediction accuracy.
• To identify effective strategies for reliable calibration transfer in pharmaceutical analysis.

Main Methods:

• Quantitative near-infrared diffuse-reflectance spectroscopy was employed.
• Six instruments were utilized: five scanning grating and one Fourier-transform, with and without fiber-optic probes.
• Calibration transfer methods evaluated included slope/bias correction, standard normal variate (SNV) transformation, local centering, standardization with a certified standard, and direct transfer.
• Wavelength accuracy was assessed using a certified diffuse-reflectance wavelength standard.

Main Results:

• Successful calibration transfer between different NIR instruments was demonstrated using a structured procedure.
• Simple transfer techniques (slope/bias, SNV, local centering) yielded significantly lower prediction errors compared to direct transfer or standardization.
• Incorporating multiple instruments into the initial calibration improved transferability.
• No significant impact on prediction errors was observed for wavelength scale differences below +/-0.3 nm.

Conclusions:

• Quantitative NIR calibrations can be effectively transferred between instruments with appropriate methods.
• Preprocessing techniques and simple transfer functions are more effective than direct transfer or standardization.
• Multi-instrument calibration enhances the robustness of transferred models.
• Wavelength accuracy within +/-0.3 nm does not critically affect calibration transfer performance.