SBIR Phase I: Development of a Differential Long-Path Spectrophotometer for On-line Measurements of Controlled Halogenated Organic Compounds in Potable Water

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This Small Business Innovation Research Phase I project is concerned with the development of a Differential Long-path Spectrophotometer (DLS) for on-line measurements of halogenated organic species that are formed when potable water is disinfected (disinfection by-products, or DBPs). The instrument to be developed will eliminate major difficulties that water utilities currently face in their efforts to monitor and control DBPs. Specifically, whereas at present the analyses of interest are extremely costly and time-consuming, the new instrument will provide inexpensive and virtually instantaneous data, allowing utilities to monitor DBP formation in real time and to respond rapidly if DBP concentrations exceed acceptable bounds. The key technical feature of the DLS will be its ability to measure, with high precision, the relatively small changes in light absorbance by natural organic matter (NOM) caused by addition of chlorine to potable water (the differential absorbance). These changes will be correlated with the concentration of individual DBPs formed and of a composite parameter characterizing the total chlorinatedDBP concentration in solution, the total organic halogen (TOX). The key concept behind DLS is the extremely strong correlation, first identified by sub-contractors of this proposal, between the differential absorbance and the concentration of the target compounds. The DLS measurements needed to quantify the formation of DBPs are fast and inexpensive. They do not involve the use of any toxic chemicals or organic solvents. Thus, the DLS instrument will address social, engineering and analytical needs and will fill an existing niche in the market of analytical instrumentation. The Phase I project will include the design and assembly of one or two working DLS prototypes and initial testing of the prototype(s) under laboratory and field conditions.Phase II will involve full development and tests of the prototypes and extensive evaluation of the performance parameters (e.g., sensitivity, dynamic range, stability), and will result in a tested and calibrated prototype device. Sequoia intends to carry out the transition to market.