TITLE: APPARATUS FOR DETECTION OF SOIL AND
WATER CONTAMINANTS BY ORGANIC COM¬ POUNDS
CITATION TO PRIOR U.S. APPLICATION
This is a continuation application with respect to
U.S. Application Serial No. 08/515,261 , filed August 15,
1995 (15.08.95). Sole inventorship with respect to this Application and each of the foregoing lies with the present
Applicant.
FIELD OF THE INVENTION Applicant's invention relates to environmental analysis, and particularly to analysis of contamination of soil and water.
BACKGROUND OF THE INVENTION Quantitatively determining the levels of organic contamination in a sample of water or soil by visually comparing the color and intensity of a Friedel-Crafts [FC] product, produced by adding excessive amounts of a Lewis acid catalyst to an extract of the sample, was disclosed in Hanby, U.S. Patent No. 4,992,379 [hereinafter Hanby I]. Using the method of Hanby I, the FC product produced was then visually compared to a series of photographs of the FC products produced by standardized samples of various contaminants in known quantities to determine the quantity of contaminants present. Although the human eye is capable of extremely accurate comparisons, the method of Hanby I can only provide relatively good quantitative information. Qualitative (i.e.
chemical identification) can only be obtained by having precise spectral data relating specific wavelengths to chemical structure.
In addition, the process disclosed in Hanby I specified the use of an alkyl halide and particularly carbon tetrachloride. This requirement was necessary in order to achieve low level (i.e. 1 ppm or less) contami¬ nation. For applications not requiring this level of sensitivity (i.e. applications in the 500 ppm or above range), Hanby II permits the use of non-halogenated solvents (e.g. heptane); thus, involving acylation type FC reactions as opposed to akylation reactions. Acylation reactions produces precipitates that are not necessarily visually differentiable whereas the spectrophotometer is capable of uniquely identifying and quantifying these precipitates.
The present invention [Hanby II] eliminates subjective factors that affected the reproducibility of results obtained using Hanby I by incorporating a light source, fiber optic cable, and a charge coupled device (CCD) spectrometer to measure the wavelength and intensity of the light reflected from the FC product. The electronic output from the spectrometer is then compared, using a digital computer, to the electronic signals or "fingerprints" produced by known samples of various contaminants. By using a computer to match the signals produced by the sample under investigation to the fingerprints, the reproducibility of results is greatly enhanced. In addition, by using spectral analysis, Hanby II is capable not only of determining quantitative levels of contaminants in samples but also of identifying the chemical composition of the sample. While certainly not the first use of spectrometry to identify environmental samples, it is the first use of visible spectrometry in combination with Friedel-Crafts reactions for the analysis of environmen¬ tal contamination.
SUMMARY OF THE INVENTION It is an object of this invention to provide a novel, useful and nonobvious portable device for inexpensively and accurately detecting organic contaminants in the soil or water.
It is a further object of this invention to provide a novel, useful, and nonobvious device for detecting organic contaminants that eliminates subjective interpretations of the results.
It is a further object of this invention to provide a novel, useful, and nonobvious device for detecting organic contaminants that incorporates a CCD spectrometer to eliminate subjective interpretations that can result by visually comparing FC products to standardized samples.
It is a further object of this invention to provide a novel, useful, and nonobvious device for detecting organic contaminants that does not require potentially hazardous alkyl halides such as carbon tetrachloride.
BRIEF DESCRIPTION OF THE DRAWINGS Applicant's invention may be further understood from a descrip- tion of the accompanying drawings wherein, unless otherwise specified, like reference numbers are intended to depict like components in the various views.
Figure 1 is a diagram of the present invention. Figure 2 is a cross section of the fiber optic cable.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention comprises a housing 1 having an opening in its top surface. The opening is dimensioned to receive a test tube 2, test tube 2 containing the Friedel-Crafts [FC] product of an extracted sample of soil or water. The FC product is produced using the method disclosed in Hanby, U.S. Patent No. 4,992,379 incorporated by reference herein.
Module 5 resides within housing 1 and is adapted to receive test tube 2 and fiber optic probe 8 such that fiber optic probe 8 is located proximally to test tube 2. In the preferred embodiment, module 5 is made from an opaque, non-reflective, and black material that minimizes stray light interference. Module 5 includes a first chamber 6 that is
dimensioned to receive test tube 2 through the opening in the top surface of housing 1. Module 5 also includes second chamber 7 that is dimensioned to receive fiber optic probe 8. Second chamber 7 extends through module 5 into first chamber 6 such that when test tube 2 is positioned within chamber 6, fiber optic probe 8 can be inserted into second chamber 7 to an adjustable position proximal to test tube 2.
Figure 2 depicts a cross section of the preferred embodiment of fiber optic probe 8. Probe 8 comprises a casing 15 that encloses six source fibers 9 and a single reflectance fiber 10. As shown in Figure 1 , source fibers 9 and reflectance fiber 10 are contained in probe 8. The source fibers 9 are connected to light source 11 and conduct light to test tube 2. Reflectance fiber 10 conducts the light reflected off of the FC precipitate in test tube 2 to CCD spectrometer 12. Returning to Figure 2, in the preferred embodiment, the source fibers 9 and the reflectance fiber 10 are each 200 μ.π, in diameter and are designed to promote extremely efficient and coherent transmission of the wavelengths critical to this analytical procedure (i.e. 450 nm to 575 nm). This portion of the visible spectrum is the most diagnostic region for this method.
In the preferred embodiment, a tungsten-halogen light source providing light energy across the visible spectrum, powered by a rechargeable battery (not shown) is used as light source 1 1. Light emitted from light source 1 1 is transmitted over source fibers 9 into probe 8 and reflected off the FC precipitate. The light reflected off of the FC precipitate is conducted over reflectance cable 10 into CCD spectrometer 12 where the optical signal is transduced into an analog electrical signal by spectrometer 12.
CCD Spectrometers are well known in the art. See, e.g.. Prytherch, U.S. Patent No. 5,235,402 and references cited therein. In the preferred embodiment, a commercially available CCD spectrometer that incorporates the single fiber optic as described is used. Such a device is available from Ocean Optics, Inc., of 1 104 Pinehurst Road, Dunedin, Florida 34698-5427; (813) 733-2447.
In the preferred embodiment, the analog electrical signal output from CCD spectrometer 12 is routed, via ribbon cable 13, through an opening 3 in the side of housing 1 , to external computer 14 where the signal passes through a conventional analog-to-digital converter. Using appropriate software, the digital signals are then compared with stored signals produced from known samples. By matching the signals produced by the test sample to the stored images produced by the known samples, computer 14 can determine what quantities of contami¬ nants are present in the sample. Alternatively, the present invention could incorporate its own microprocessor, on-board ROM, and a simple LED display for internal analysis of the samples.
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions will become apparent to persons skilled in the art upon the reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.