The feasibility of detection of trace elements in corn stover based on their interference effect on the near-infrared peak of water

Trace elements affect various processes of biomass utilization, and it is necessary to measure them. Near-infrared spectroscopy (NIRS) can quickly and accurately detect multiple components in biomass. However, trace elements have no absorption peaks in the NIR spectral region. It is challenging to detect trace elements by NIRS. In this study, the feasibility of NIRS for the detection of trace elements in biomass was investigated by utilizing the interference effect of trace elements on chemical bonding in biomass. The corn stover powder was selected for the study. The samples were pretreated by drying, water-washing, acetic acid washing, and nitric acid washing. By studying the spectra of different samples, it was found that the trace elements interfered with the absorption peaks of O–H bonds at 1140 nm – 1160 nm, 1260 nm – 1320 nm, 1440 nm – 1500 nm, and 1560 nm – 1600 nm, and C–H bonds at 1320 nm – 1360 nm in the corn stover samples. Meanwhile, the free and bound water contents in the samples affect this interference. Among them, the free water content of the sample has a more significant effect on the interference of trace elements. In the wavelength bands of 1100 nm – 1180 nm, 1240 nm – 1360 nm, 1380 nm – 1500 nm, and 1550 nm – 1650 nm, the higher the free water content of the sample, the more pronounced the interference effect of trace elements. This study provides a theoretical basis for detecting trace elements in biomass by NIRS.