In the present paper we report that near-infrared spectroscopy is a useful tool for analyzing solutes in solution in common organic solvents. This is because the near-infrared absorptions of the solvent are not so strong as to disturb the separation of the characteristic near-infrared bands, by subtraction, of the solute. To demonstrate this capability, we first showed that the near-infrared absorptions of heptane and toluene, each of which represents aliphatic or aromatic solvents, do not significantly affect the noise level of the difference spectrum, in which the near-infrared spectrum of a solute is to be separated by subtraction. Second, we showed that the characteristic near-infrared absorptions of 1-heptene as a solute were well separated from the spectrum of the solution in heptane and toluene. Four of the five indicator bands of 1-heptene were recognizable and sufficiently detected at the almost limiting concentration of 0.1% (v/v) in both solvents. The minimum magnitude of the detectable signal is discussed in terms of the signal-to-noise ratios of the indicator bands. As an application, we investigated the interaction properties of a C≡CH group of 1-heptyne from the CH stretching fundamental, combination, and overtone bands in the pure liquid and in solution in three solvents at various concentrations.
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.
Contact your librarian or system administrator
Login to access OSA Member Subscription