Optics: measuring and testing – For light transmission or absorption – Of fluent material
Reexamination Certificate
2002-05-30
2004-12-14
Toatley, Jr., Gregory J. (Department: 2877)
Optics: measuring and testing
For light transmission or absorption
Of fluent material
C356S367000, C250S373000, C600S322000
Reexamination Certificate
active
06831746
ABSTRACT:
BACKGROUND
The present invention is directed to a system, method, and apparatus for determining concentration of a solute in a solution. In particular, the present invention is directed to a system, method, and apparatus for determining concentration of a solute in a solution in a non-intrusive manner.
It is often desirable to be able to determine the concentration of a solute in a solution. For example, it is desirable to be able to determine the concentration of chlorine in treated water.
Active chlorine content of treated water is typically 1-10 ppm, and nominally levels are less than 5 ppm. However, those levels may rise as high as 10 ppm during shock treatments.
Conventional commercial chlorine detectors have many drawbacks. For example, they do not produce results in real time and often require human intervention to make interpretations based on color matching. Also, they typically employ a reagent that contaminates water supplies. Furthermore, they lack support electronics to control chemical feed and/or water quality control.
Most substances absorb radiation in the UV/VIS/NIR (Ultra Violet/Visible/Near Infrared) regions of the electromagnetic spectrum. Each chemical species allows a specific amount of light of a given wavelength to be transmitted, thus creating a “signature” for that species due to the wavelength-dependent index of refraction. By strategically picking off peaks in absorption (attenuation of a particular wavelength band), it is possible to classify and even quantify various chemical species.
Theories have been posited for utilizing absorption spectra in the UV region to detect concentration of a solvent in a solution. For example, “Water-core waveguide for pollution measurement in the deep ultraviolet”, by Peter Dress et al. describes evaluation of the performance of UV fibers and their degradation over time due to excessive exposure. There is a significant absorption peak for active chlorine centered at 290 nm for a pH of 10.2, as observed in Dress et al. This peak can shift in wavelength depending on pH of the water sample. With decreasing pH, the absorption peak shifts to lower wavelengths or higher energies, while the opposite effect is observed with increasing pH. While Dress et al. suggests use of absorption spectra to detect chlorine concentration, this paper presents data showing poor results below 10 ppm.
In “Flow-injection chemiluminescence sensor for the determination of free chlorine in tap water”, by Wei Qin et al., chemiluminescence is explained. One of the drawbacks of the method described in Qin et al. is that it requires an injection of the reagent luminol. Also, Qin et al. reports a lack of sensitivity required for low concentration measurement.
There is thus a need for a non-invasive and non-destructive technique for determining low level concentrations of a solute in a solution.
SUMMARY
It is therefore an object of the present invention to provide a system, method, and apparatus for detecting concentration of a solute in a solution in a non-invasive, non-destructive manner.
According to exemplary embodiment, this and other objects are met by a system, method, and apparatus for determining concentration of a solute in a solution. Light from a light source is received at a chamber containing the solute and the solution. The light is transmitted along an optical path length of the chamber, through the solute and the solution, and output from the chamber. The light output from the chamber is detected by a detector. The optical path length of the chamber is selected to optimize sensitivity of the detector. The concentration of the solute in the solution is determined based on the light received by the detector.
The objects, advantages and features of the present invention will become more apparent when reference is made to the following description taken in conjunction with the accompanying drawings.
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Article entitled Flow-Injection Chemiluminescence Sensor for the Determination of Free Chlorine in Tap Water, by Qin et al., published inAnalytical Letters, 30(1), 11-19 (1997).
Article entitled “Water-core waveguide for pullution measurements in the deep ultraviolet”, by Dress et al., published inApplied Optics, Jul. 20, 1998, vol. 37, No. 21, pp 4991-4997.
Ardrey William
Cassidy Christopher S.
Church Kenneth H.
Teague Keith
Needle & Rosenberg, PC.
Nguyen Sang H.
Sciperio, Inc.
Toatley , Jr. Gregory J.
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