Online Measurement of Phenols in Wastewater by Membrane Inlet-VUV Ionization-Time of Flight Mass Spectrometry

Developing new methods for online monitoring of phenols in wastewater is highly demanding, as phenols are common pollutes in wastewater from dying, coking and papermaking industry. In this work, a new method was introduced for online determination of phenols in wastewater by membrane inlet-vacuum ultraviolet (VUV) ionization-time of flight mass spectrometry (TOFMS). The fragment-free ionization technique (single-photon ionization, SPI) using vacuum ultraviolet (VUV) lamp was especially useful for online measurement of organic compounds without pre-separation. Phenols was introduced directly into MS through polydimethylsilane (PDMS) membrane after derivatization, the analysis time of individual sample was less than 15 min. Parameters, such as the acetylation reaction time, pH, the added amount of acetic anhydride and flow rate, etc, were optimized. At optimization condition, the limits of detection for phenol, 3-methylphenol, 2-chlorophenol, 2,4-dichlorophenol are 3，6，8，14 μg•L^-1, respectively, and the linear dynamic ranges are two orders. The present online monitoring method of phenols shows great potential applications to detect phenols in wastewater.