A new and rapid analysis method for the most important herbal squalene source: Comparison of UV-visible, fluorescence, and FTIR techniques for the quantification of squalene in amaranth seed oil

A new method for the quantification of squalene in amaranth seed oil (ASO) is proposed. The spectroscopic techniques of ultraviolet-visible (UV-vis), fluorescence, and Fourier transform infrared (FTIR) were tested using partial least square (PLS) calibration models. Based on the results obtained from the reference chromatographic method, two ASO samples with the highest and lowest concentrations among totally 40 ASO samples were selected to prepare the calibration set (CS) (n = 20). All ASO samples were also kept as prediction set (PS) for the control of the predictive capacity of the chemometric model to be developed. To quantify the squalene compound in ASO, a totally of 26 PLS calibration models were tested using all spectroscopic techniques with various spectral pretreatments, and the best PLS model was selected by evaluating their statistical values of root mean square error of calibration (RMSEC), root mean square error of cross-validation (RMSECV), and R-square. The best calibration model was obtained from normal spectra in FTIR spectroscopy (4000-400 cm-1) with the lowest RMSEC of 0.0930, RMSECV of 0.1301, and the highest R-square of 0.9989 for calibration. The results of this study revealed that FTIR spectroscopy coupled with PLS regression could be used for fast, accurate, and environment-friendly quantification of squalene present in ASO samples.

Automated summary

A new method for quantifying squalene in amaranth seed oil was proposed using spectroscopic techniques and partial least square calibration models. The best calibration model was obtained from FTIR spectroscopy with normal spectra, showing low RMSEC and high R-square values. The study demonstrated that FTIR spectroscopy coupled with PLS regression is an effective and environmentally friendly way to quantify squalene in ASO samples.