Efficient Detection of Limonoid From Citrus Seeds by Handheld NIR: Compared with Benchtop NIR

Biological activities of limonoid include antitumor, antioxidant, anti-inflammatory, etc., and its content in citrus seeds is particularly high with a low utilization rate, so it is an important potential source of limonoid. The miniature near-infrared spectra device provides a high-throughput, low-cost, and field analysis technique for the detection of limonoid from it. In this paper, the quantitative determination of limonin, nomilin, and obacunone in citrus seeds by a NIR instrument, and a precise benchtop NIR instrument were studied. UHPLC-MS/MS was applied as the reference analysis method. The root mean square error (RMSE), determination coefficient (R2), and the ratio of performance to deviation (RPD) were used to monitor the model. R2p, RPD, and RMSEp of the best model based on benchtop TANGO FT-NIR for limonin, nomilin, and obacunone were 0.8920/3.10/0.0141, 0.9250/3.72/0.0058, and 0.9081/3.36/0.0040, respectively, representing reliable results. The miniature device NIR-S-G1 was also good in the model for nomilin (0.9075/3.35/0.0097) and obacunone (0.8860/3.02/0.0050). This result indicated that the miniaturized NIR-S-G1 has a similar ability to TANGO FT-NIR in detecting nomilin and obacunone in citrus seeds. Their experimental NIR absorption was detected to better understand the characteristics of the model. This step, combined with the waveband selection algorithm and the two-dimensional correlation spectroscopy (2D-COS) analysis, explained the main factor that affects the difference in analytical performance between the two spectrometers: detection range and instrument resolution.Graphical abstract