Rapid Determination of Nitrate in Chinese Cabbage Using Fourier Transforms Mid-infrared Spectroscopy

The nitrate content in Chinese cabbage was rapidly predicted using mid. infrared spectroscopy (diffusion reflectance spectroscopy, photoacoustic spectroscopy and attenuated total reflectance spectroscopy). There were interferences in the characteristic bands of nitrate (1200-1500 cm(-1)) for all the infrared spectra, in which the interferences for diffusion reflectance spectra were strongest, followed by photoacoustic spectra, and the weakest for the attenuated total reflectance spectra, which were verified by the principal component regressions between infrared spectra and nitrate content in Chinese cabbage. The linear regression coefficients (R-2) were 0. 4003, 0. 4874 and 0. 8741, respectively. Based on attenuated total reflectance spectra, the chemometrics method of partial least squares was involved to improve the prediction model of nitrate, which significantly decreased the prediction error. The correlation coefficient was 0. 8851, and the RPD value (SD/RMSEP) was 3. 19. Therefore, the technique of mid. infrared attenuated total reflectance spectroscopy can be applied for the rapid monitoring of nitrate in Chinese cabbage.