On-line monitoring of reactions of epichlorohydrin in water using liquid membrane introduction mass spectrometry

The industrially significant chain extender epichlorohydrin (chloromethylox irane) can be quantified on-line at the low parts per million level in aque ous solution using membrane introduction mass spectrometry (MIMS). Solid me mbranes composed of microporous poly(tetrafluoroethylene) (PTFE) and nonpor ous silicone were used to establish this methodology using an ion trap mass spectrometer; both gave similar performance, even though they are based on different transport mechanisms. In addition, a liquid polyphenyl ether mem brane reinforced with a microporous support was shown to give similar resul ts. The predominant ions produced in an ion trap mass spectrometer using el ectron ionization (EI) were mit 57 ([M - Cl](+)) and 62/64 ([M - CH2O](+)) while those produced under chemical ionization (CI) conditions were mit 57 ([M+ H - HCl](+)), 63/65 ([M + H - CH2O](+)), and 93/95 ([M + H](+)). Furth er, the hydrochloric acid-catalyzed ring opening of epichlorohydrin to yiel d 3-chloro-1,2-propanediol and other products was monitored on-line using t he polyphenyl ether liquid membrane. The ability to perform continuous moni toring provides access to real time kinetic data unavailable through off-li ne chromatographic techniques.