Membrane Preconcentration Technique for the Colorimetric Detection of Trihalomethanes in Water

We present a preconcentration and colorimetric sensing platform for detection of trihalomethanes (THMs) in water. The Environmental Protection Agency (EPA) regulates the four chief THM constituents (bromoform, chloroform, bromodichloromethane, and dibromochloromethane) to a limit of 80 parts per billion (ppb) [nL/L] in treated water. Currently, expensive and non-portable analytical techniques are used for detection of THMs in treated water samples. Here, we utilize the Fujiwara reaction which is an inexpensive colorimetric detection reaction that, in the presence of a THM and basic conditions, forms a chromophore that emits a red/pink color under visible light absorption. This reaction, however, is limited to a visible detection range of (μL/L). To increase sensitivity, we have developed a Fujiwara preconcentration system utilizing a superhydrophobic membrane to decrease the detectable limit of this reaction making the colorimetric technique applicable to real-world applications. This Fujiwara preconcentration system has the ability to allow THM vapor through the membrane allowing the Fujiwara reaction to occur with a minute amount of a THM. Two types of superhydrophobic membranes [polypropylene (PP) and poly(4-methyl-1-pentene) (P4M1P)] will be used. In this presentation, the optimization of the Fujiwara stoichiometry, membrane conditions, and geometry of the system will be discussed.