Differentiation and quatification of free chlorine and inorganic chloramines in aqueous solution by MIMS

A membrane introduction mass spectrometric (MIMS) method for differentiatio n and quantification of free chlorine and inorganic chloramines in aqueous solution was developed based on a law-cost mass spectrometer. Several facto rs were examined for system optimization. Only membrane temperature and liq uid flow rate exerted substantial influences on the performance of MINIS. E ssentially linear response curves over several orders of magnitude of conce ntrations were observed, and limits of detection for free chlorine and mono -, di-, and trichloramine at 0.1, 0.1, 0.02, and 0.06 mg/L as Cl-2, respect ively, were demonstrated. System performance was evaluated with chlorinatio n of ammoniacal water. Similar results were obtained by the MIMS method, co nventional DPD/FAS titration, and UV-visible spectroscopy. Identification a nd quantification of inorganic chloramines by the MIMS method and DPD/ FAS titration were also compared for chlorination of an aqueous solution contai ning glycine as the nitrogen source as well as samples of potable water and wastewater. These experiments demonstrated an advantage of MIMS relative t o titration in that MIMS was able to unambiguously quantify and characteriz e the inorganic chlorine residual.