title: Quantitative measurements of amino acids by terahertz time-domain transmission spectroscopy.
abstract: The quantitative analysis of amino acids by terahertz (THz) time-domain absorption spectroscopy is demonstrated. The optical densities of the amino acids were found to be linearly proportional to the concentration. The molar absorption coefficients of L-glutamic acid (L-Glu), L-glutamic acid sodium salt (Na-L-Glu), L-glutamic acid hydrochloric salt (HCl-L-Glu), L-cysteine (L-Cys), and L-histidine (L-His) were calculated by averaging the THz spectra of the amino acids at several different concentrations in approximately the 0.2-1.0 mol L(-1) range. The concentrations of L-Glu, L-Cys, and L-His mixed samples were successfully calculated with errors of less than 11% and 20% when their concentrations were higher than 0.45 and 0.22 mol L(-1), respectively, by using the obtained molar absorption coefficient.
authors.affiliation: NTT Basic Research Laboratories, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198 Japan. ueno@aecl.ntt.co.jp
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ueno
authors.forename: Rakchanok
authors.initials: R
authors.lastname: Rungsawang
authors.forename: Isao
authors.initials: I
authors.lastname: Tomita
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Ajito
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D007834:Lasers; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors
chemical_list: D000596:Amino Acids