Comparison of the vibration mode of metals in HNO3 by a partial least-squares regression analysis of near-infrared spectra.
The near-infrared (NIR) spectra of such metals as Cu(II), Mn(II), Zn(II) and Fe(III) in HNO(3) in the 700-1,860 nm region were subjected to a partial least-squares regression analysis and leave-out cross-validation to develop chemometric models. The models yielded a coefficient of determination in cross validation of 0.9744 [Cu(II)], 0.9631 [Mn(II)], 0.9154 [Zn(II)] and 0.741 [Fe(III)]. The regression coefficients for Cu(II), Mn(II) and Zn(II), but not for Fe(III), showed strong negative peaks at around 1,050-1,200 nm, a zone where spectral bands have been reported to decrease with increasing pH value. A positive peak at around 710-750 nm, which may have been due to water absorption, was observed in regression coefficients of Cu(II), Mn(II) and Zn(II) but not in Fe(III), while a negative peak was observed in that for Fe(III) at around 710-750 nm. These results indicate that the divalent cations [Cu(II), Mn(II) and Zn(II)] showed different absorption in the NIR region from the trivalent cation [Fe(III)], suggesting that the vibration mode of water, which mirrors the interaction between cations and water, may be influenced by valency.
Sakudo
Akikazu
A
School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan.
Tsenkova
Roumiana
R
Tei
Kyoko
K
Onozuka
Taisuke
T
Ikuta
Kazuyoshi
K
Yoshimura
Etsuro
E
Onodera
Takashi
T
D002412:Cations; D003300:Copper / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D016018:Least-Squares Analysis; D008345:Manganese / Q000737:chemistry*; D008956:Models, Chemical; D017942:Nitric Acid / Q000737:chemistry*; D019265:Spectroscopy, Near-Infrared; D014867:Water / Q000737:chemistry; D015032:Zinc / Q000737:chemistry*
D002412:Cations; D014867:Water; D017942:Nitric Acid; D008345:Manganese; D003300:Copper; D007501:Iron; D015032:Zinc