Quantitative determination by temperature dependent near-infrared spectra: a further study

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Physical Chemistry

Background:

• Quantitative spectra-temperature relationship (QSTR) models were previously established for near-infrared (NIR) spectra and temperature.
• Further investigation is needed to assess the practical applicability of QSTR for quantitative analysis.

Purpose of the Study:

• To evaluate the applicability of the QSTR model for quantitative determination of aqueous ethanol.
• To explore the use of limited spectral data and varying temperatures for accurate analysis.
• To investigate both linear and nonlinear calibration curves for different concentration ranges.

Main Methods:

• Acquisition of NIR spectra for aqueous ethanol samples across a temperature range of 31-40°C.
• Development of QSTR models using spectral data within small temperature intervals.
• Application of linear and nonlinear curve fitting for calibration across diverse concentration ranges (1-5%, 20-70%, 95-99% v/v).

Main Results:

• The QSTR model can be successfully built using spectra from a narrow temperature range.
• Quantitative analysis is achievable with only two spectra recorded at different temperatures.
• Both linear and nonlinear calibration curves demonstrated applicability across all tested concentration ranges.

Conclusions:

• Temperature-dependent NIR spectra offer a novel and efficient method for quantitative determination.
• The QSTR model shows significant potential for applications in bio-fluid analysis and industrial settings.
• Minimal spectral data and temperature variations are sufficient for robust quantitative analysis.