Ultraviolet-visible online detection

Post-column detection of chlorophyll derivatives is often accomplished by ultraviolet and visible spectroscopic techniques, which take advantage of the strong electronic absorption spectra of these pigments (units F4.3 F4.4). While these methods have enjoyed wide application (Schwartz et al., 1981 Khachik et al., 1986), a major advance was made with the introduction of photodiode array (PDA) detection. Multichannel photodiode array detection allows for simultaneous monitoring of multiple wavelengths, resulting in the generation of online electronic absorption spectra of a compound as it elutes from the HPLC column. Because of the uniqueness of electronic absorption spectra of individual chlorophyll derivatives, these techniques have enjoyed extensive application for tentative identification of components from complex mixtures and extracts... 

Equipment is available that can employ laboratory analytical teclmiques in instruments suited for online monitoring and detection of oily contaminants. These instruments use the principles of solvent extraction, infrared, spot testing, TOC measurement and photometric measurement of visible and ultraviolet adsorbence. They are not subject to interferences from suspended solids, air bubbles, color, oil droplet size, or dissolved solids in the water. 

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