Application of Orthogonal Signal Correction for Near Infrared Spectroscopic Calibration Transfer of Crude Protein of Straw Silage
This study is focus on the orthogonal signal correction based on different pretreatment methods for near infrared spectroscopy(NIRS) calibration transfer of straw silage.Up to 141 straw silage samples with known crude protein content and two Fourier transform instruments(master instrument: SPECTRUM ONE NTS,slave instrument 1: ANTARIS),one scanning grating instrument(slave instrument 2: FOSS 6500) were involved.Four pretreatment methods,control,local centering,global centering and Z-score standardization,for orthogonal signal correction were tested and evaluated.The results showed that the orthogonal signal correction with the local centering,the global centering and the Z-score standardization methods worked successful for calibration transfer between two Fourier transform instruments.The local centering and the global centering gave almost equally good results which was better than that of Z-score standardization method.However,for calibration transfer between Fourier transform and scanning grating instruments,only global centering method gave acceptable result while the other three methods were hard for application of practical prediction.