Wl. Yoon et al., Construction and transferability of a spectral library for the identification of common solvents by near-infrared transflectance spectroscopy, ANALYST, 124(8), 1999, pp. 1197-1203
A transflectance near-infrared spectroscopic method has been developed for
the identification of 15 common solvents using correlation in wavelength sp
ace as the identification algorithm. Second-derivative absorbance spectra o
ver the wavelength range 1136-2000 nm were found to give the optimum condit
ions for distinguishing between the solvents. The spectral library was test
ed on eight instrumental setups and found to be directly transferable betwe
en different instruments not only from the same manufacturer, but also betw
een grating and Fourier transform systems. Identification was not affected
by small changes in temperature or optical path length. The presence of wat
er could easily be detected by visual insepection of the solvent spectra. H
owever, small traces of water did not normally interfere with the identific
ation process. Correlation coefficient values between a given solvent from
different batches and/or between different instruments were generally > 0.9
9. Values < 0.99 invariably indicated the presence of impurities. Mixtures
of similar solvents such as ethanol-methanol could not always be reliably d
ifferentiated from that of the pure solvent at the highest concentration.