Organic contaminants, e.g., certain halogenated organic compounds and polyaromatic hydrocarbons, can find their way into the environment through industrial operations and through the use of pesticides. While many of these compounds have been banned or restricted due to potential health hazards, their presence continues in soil and water samples.
Analysis of water and/or soil samples for halogenated organic compounds has traditionally been conducted by addition of an immiscible solvent, e.g., chloroform, to a water sample whereby the halogenated organic compounds will concentrate in the organic phase, i.e., the immiscible solvent (see Test Methods for Evaluating Solid Wastes, Physical/Chemical Methods, SW-846, U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, 3rd edition, Dist. of Columbia (1987) describing an EPA approved method, i.e., method 8080 for Organochlorine Pesticides and PCB's wherein aqueous extractions are conducted by either method 3510--Separatory Funnel Liquid-Liquid Extraction or method 3520--Continuous Liquid-Liquid Extraction, each method requiring large amounts of solvents and considerable time). The solvent phase is then separated from the aqueous phase, the majority of the solvent evaporated off and the halogenated organic compound residue analyzed by standard techniques.
Several repetitions of such an organic phase separation process are generally necessary thereby resulting in the use of a significant volume of solvent. Drawbacks to this traditional organic phase separation process include that it is time-consuming, is often rather imprecise and inaccurate, and presents a further environmental problem by the use and potential for release of chlorinated solvent into the atmosphere as the solvent is removed prior to analysis.
Another analytical technique referred to as solid phase extraction has also been used for separation of organic compounds from aqueous samples. This method uses silica particles coated with selected organic molecules, e.g., polyalkylenimino alkyl polyalkoxy silanes or carboalkoxyalkyl silanes, such silica particles often referred to as bonded phase silicas. The coated silica particles are packed into a chromatographic column and a water sample is percolated through the packed column. Organic compounds within the water sample are attracted to the surface coating on the silica and thus be separated from the water. The organic compounds can then be separated from the packed bed by flushing with a small amount of solvent. This method uses significantly less solvent than the traditional method. However, drawbacks of solid phase extraction include: the potential for decomposition of the coating on the silica particles under certain conditions, e.g., under wide pH fluctuations; the tendency for clogging of the packed columns due to the small particle size; the tendency of the coated silica particles to adsorb water which must be subsequently removed; and, the potential for interference during subsequent analysis of a water sample due to compounds added to the coated silica particles during their manufacturing process. Thus, techniques other than traditional organic phase separation or solid phase separation are still desirable for sample preparation prior to the analysis of water samples.
It has been known that many organic compounds, especially halogenated organic compounds, are attracted to polyolefin material such as polyethylene and polypropylene. For example, U.S. Pat. No. 4,276,179 discloses removal of halogenated hydrocarbons from aqueous solutions by contact with microporous polyolefinic absorbents. However, there is no disclosure regarding removal of the halogenated hydrocarbons from the microporous polyolefinic absorbents or determination of halogenated hydrocarbon concentrations in the initial aqueous sample.
One object of this invention to provide an apparatus and process for sample preparation prior to a standard analysis for organic contaminants, e.g., halogen-containing hydrocarbons, in a water sample.
A further object of this invention to provide an apparatus and process for sample preparation prior to a standard analysis for organic contaminants, e.g., halogen-containing hydrocarbons, in a water sample wherein the sample preparation does not require substantial quantities of solvent in separating the organic contaminants.
Yet another object of this invention to provide an apparatus for sample preparation prior to a standard analysis for organic contaminants, e.g., halogen-containing hydrocarbons, in a water sample wherein the apparatus is substantially free of clogging problems and does not undergo the retention of water.
A still further object of this invention to provide an apparatus and process for sample preparation prior to a standard analysis for organic contaminants, e.g., halogen-containing hydrocarbons, in a water sample wherein the sample preparation provides cleaner extracts in a quicker process and the apparatus can be reused rather than discarded as are the presently available solid phase extraction materials.
USPTO Backgrounds
USPTO Backgrounds