Application of Resonance Raman Spectrometry to Effluental Analysis in High Performance Liquid Chromatography

Abstract

For the sensitive and selective analysis of high performance liquid chromatography(LC) effluents, a new detection system with resonance Raman spectrometry was developed. A micro LC was coupled with a laser Raman spectrometer by a quartz tube flow cell. This cell, connecting with a micro column directly, was simply inserted into the capillary holder in the sample compartment of the Raman spectrometer. The resonance Raman effect was measured with 488 nm line of Ar+ laser at 200 mW output. Several derivatives of 4-dime-thyldminoazobenzene(DAAB) eluted from a separation column (packing: ODS silica, eluent: methanol) were detected continuously by measuring the intensity of resonance Raman scattering at 1406 cm-1, since Raman lines were observed for all compounds at about this wave number. A chromatogram obtained by this method was found to be similar to the one obtained by UV detector. The relation between the Raman intensities for 1406 cm-1 and the concentration of 2′-chloro-4-DAAB injected into LC was linear up to 260ng/^iJ. A detection limit of 2ngμ was obtained by this method. Moreover, rapid identification of compounds possessing almost the same retention time was made by means of the operation in a stop-and-go mode. By measuring Raman spectra on the condition of stopping the flow of LC at the retention time of 2/-chloro-4-DAAB and by paying an attention to the characteristic Raman lines (1253 cm″1 and 1195 cm″1 for 2r~ chloro-4-DAAB, 1224 cm″1 for 3′-methyl-4-DAAB), it became possible to detect above two compounds separately which could not be separated by UV detector. LC-Raman proved to be a useful detection system with both high sensitivity and excellent selectivity for colored compounds. © 1980, The Chemical Society of Japan. All rights reserved.