Quantitative measurements of binary amino acids mixtures in yellow foxtail millet by terahertz time domain spectroscopy.
Terahertz time domain spectroscopy (THz-TDS) combined with chemometrics has been utilized for the qualitative and quantitative analysis of binary mixtures of l-glutamic acid and l-glutamine which have similar chemical structures and properties. The binary mixtures of amino acids were prepared with yellow foxtail millet matrix, substituted for polyethylene (PE) as previously reported. After proper pretreatment of absorption spectra, quantitative analysis was achieved by partial least squares (PLS) and interval partial least squares (iPLS) regressions. The performance of models was evaluated based on the root mean square error of prediction (RMSEP) and correlation coefficient (R(2)) of cross-validations with bootstrapped Latin partitions as criterion. The iPLS yielded better results with low RMSEP (0.39±0.02%, 0.39±0.02%), and higher R(2) values (0.9904, 0.9906) for glutamine and glutamic acid comparing to the conventional PLS models. Multivariate curve resolution alternating least squares (MCR-ALS) was successfully applied for resolution of pure THz spectra and concentration profiles of two amino acids components from mixtures.
Department of Chemistry, Capital Normal University, Beijing 100048, China.
Shaohua
S
Lu
Department of Chemistry, Capital Normal University, Beijing 100048, China.
Xin
X
Zhang
Department of Chemistry, Capital Normal University, Beijing 100048, China. Electronic address: gusto2008@vip.sina.com.
Zhuoyong
Z
Zhang
College of Science, Minzu University of China, Beijing 100081, China.
Yuping
Y
Yang
Department of Chemistry, Capital Normal University, Beijing 100048, China.
Yuhong
Y
Xiang
D000596:Amino Acids / Q000032:analysis*; D005504:Food Analysis; D018698:Glutamic Acid / Q000032:analysis; D016018:Least-Squares Analysis; D016014:Linear Models; D015999:Multivariate Analysis; D015203:Reproducibility of Results; D032983:Setaria Plant / Q000737:chemistry*; D055068:Terahertz Spectroscopy
D000596:Amino Acids; D018698:Glutamic Acid
Amino acid; Multivariate curve resolution alternating least squares (MCR-ALS); Partial least-squares (PLS); Terahertz time domain spectroscopy (THz-TDS)