Selective trace lever analysis of phenolic compounds in water by flow injection analysis - Membrane introduction mass spectrometry

Flow injection analysis coupled with membrane introduction mass spectrometr y (FIA-MIMS) with on-line derivatization is shown to allow fast, accurate, nearly interference-free, and sensitive (low mug/L) quantitation of phenoli c compounds in water. On-line FIA derivatization of the phenolic compounds is performed by acetic anhydride acetylation in a K2CO3-buffered alkaline m edium. The phenol acetates so formed efficiently permeate a silicone membra ne and are directly transferred to the mass spectrometer, in which they are analyzed with selectivity and high sensitivity via selected ion monitoring . FIA-MIMS analysis was performed for aqueous solutions of phenol, 2-methyl phenol, 4-chlorophenol, 4-chloro-3-methylphenol, 2,4-dichlorophenol, and 2, 4,6-trichlorophenol, and detection limits in the 0.5-20 mug/L (ppb) range w ere observed for an analytical frequency of six samples/h. FIA-MIMS for phe nolic compound analysis is considerably less time-consuming and labor inten sive than most chromatographic methods based on liquid-liquid extraction an d preconcentration procedures and is therefore applicable for on-line and i n-situ monitoring of phenols in wastewaters and in the environment. FIA-MMS employing acetic anhydride derivatization is also virtually free of interf erences since it combines chemical, membrane, and enhanced MS selectivity; hence quantitation of phenolic compounds can be performed in the presence o f congeners.