Field of the Invention

The present invention relates to a process for extracting chemical compounds from a sample matπx, for example a biological fluid such as blood. The process may be utilized to extract chemical compounds including "dioxin-hke" compounds from biological fluids. The invention advantageously provides a process which achieves higher yields in shorter times than previous processes.

Background

Polychloπnated dibenzo-p-dioxin, pol ychloπ nated dibenzofurans and polychloπnated biphenyl congeners are considered amongst the most toxic compounds within a seπes generally referred to as "dioxm-like" compounds that occur as inadvertent environmental contaminants. The suspected and/or known health effects of these compounds are so severe that analytical methods for their determination in human blood serum need to reach parts-per-quadnl on (10 ^" ) levels (femtograms per milliliter of serum). Presently utilized processes are both slow and expensive, because of the difficulty in extracting such small amounts of these dioxin-hke compounds with reasonable recovery and the tedious nature of the processes used to remove mateπals other than compounds of interest that interfere with analysis

In pπor art processes, the extraction of 23,7,8-tetrachlorodιbenzo-p-dιoxιn (TCDD) from blood serum and removal of mterfeπng contaminants are generally performed as separate steps, typically requinng from several hours to several days to accomplish. Pπor attempts to simultaneously extract and puπfy TCDD from biological fluids have been unable to provide a TCDD precursor which did not require additional, tedious punfication, because of the simultaneous extraction of other biological components and contaminants.

Summary of the Invention The present invention provides a process for the extraction and punfication of chemical compounds from an aqueous sample matπx A preferred aqueous sample matπx is a biological fluid, such as blood or uπne, more preferably blood serum.

The process of the present invention may be advantageously utilized to extract and puπfy toxic chemical compounds from a biological fluid sample to determine the concentration of the compounds in the sample. In particular, the process of the present invention may be utilized to extract and puπfy dioxin-hke compounds from a biological fluid sample.

As used herein, dioxm-like compounds include chloπnated aromatic chemicals

such as polychlorinated dibenzo-p-dioxins, pol chlorinated dibenzof urans, and polychlorinated biphenyl congeners, and similar compounds which are known to affect the TEQ (toxic equivalency) value in human blood/plasma. Examples of dioxin-like compounds which may be extracted and purified utilizing the process of the present invention include, but are not limited to:

2 ,7,8- tetrachlorodi benzo-p-dioxi n (TC DD) 2,3,7,8-tetrachlorodibenzofuran (TCDF) 1 ,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD) 1 ,2,3 ,7,8-pentachlorodi benzofuran (PeCDF) 2,3,4,7,8-pentachlorodibenzofuran (PeCDF)

3,3',4,4',5-pentachlorobiphenyl (PCB 126). D The process of the present invention overcomes a problem of prior art processes for extracting dioxin-like compounds, by providing a means for chemical destruction of potentially interfering components in a sample matrix, such as blood serum. The chemical destruction occurs as a part of the overall extraction process and thus the chemical destruction does not increase the time requirement. In a preferred embodiment of the process of the present invention, a means for quantification of the recovered chemical compounds with automatic correction for recovery is provided through incorporation of an internal standard (reference compound) in such a way that recovery is not compromised.

According to the process of the present invention a high percentage of the chemical compound to be extracted in an aqueous sample matrix is transfeπed into a small volume of organic solvent through a vapor/liquid exchange process. While the exchange and transfer are occurring, a portion of the potentially interfering substances in the aqueous sample matrix are converted to non-interfeπng materials through reaction with a general catalyst of hydrolytic reactions. In a preferred embodiment, introduction of a reference standard into the serum is done in such a manner as to facilitate the subsequent transfer of the chemical compound to be measured out of its association with serum constituents. The process of the present invention permits the preparation of extracted and interference-depleted dioxin-like compounds from samples of serum in less than one hour. Since many samples can be being processed in duplicate arrangements at the same time, one person can prepare several samples for analytical determination during each hour of working time. The process of the present invention advantageously results in a higher recovery of dioxin-like compounds from aqueous samples than heretofore commonly utilized processes.

The process of the present invention may be advantageously utilized for rapid,

simultaneous extraction and punfication of dioxin-like compounds from small samples.

Another advantage of the process of the present invention is that it is simple and economical.

A further advantage of the process of the present invention is that the high recovery permits subsequent analytical measurements to be made with maximum sensitivity.

Another advantage of the process of the present invention is that sample preparation is completed in a short peπod of time.

Further details and advantages of the process of the present invention will become apparent from the following more detailed descπptions.

Bπef Descnption of the Drawing

Figure 1 is a schematic diagram of an embodiment of the process of the present invention. Figure 2 depicts the appearance of selected ion monitonng mass chromatograms of a sample prepared by the manner descπbed in the example herein. The top graph shows the detector response to the TCDD, while the lower graph shows the response to the reference (internal) standard.

Detailed Descπption of the Invention

According to the present invention, a process for extracting a predetermined chemical compound or compounds from an aqueous sample matπx compπses: diluting the aqueous sample matπx with a diluent; reacting the diluted aqueous sample matπx with a chemically active substance; boiling the resulting aqueous sample matπx to produce vapors; condensing said vapors to form a condensate, contacting said condensate with an extractant for the predetermined chemical compound or compounds, said extractant being substantially immiscible with said condensate, to extract the predetermined chemical compound or compounds and produce an extractant phase compnsmg the predetermined chemical compound or compounds, and a condensate phase depleted in the predetermined chemical compound or compounds; and separating said extractant phase from said condensate phase. The levels (concentration) of the predetermined chemical compound or compounds in the predetermined chemical compound or compounds loaded extractant phase may be determined by standard analytical techniques.

The predetermined chemical compound or compounds which may be extracted by the process of the present invention include the dioxin-like compounds referenced above

The diluting and reacting steps in the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matπx According to this embodiment of the process of the present invention a process for extracting a predetermined chemical compound or compounds from an aqueous sample matπx compnses. diluting the aqueous sample matnx with a diluent composition compnsmg a diluent and a chemically active substance which will react with the aqueous sample matπx; boiling the resulting aqueous sample matπx to produce vapors; condensing said vapors to form a condensate, contacting said condensate with an extractant for the predetermined chemical compound or compounds, said extractant being substantially immiscible with said condensate, to extract the predetermined chemical compound or compounds and produce an extractant phase compnsing the predetermined chemical compound or compounds, and a condensate phase depleted in the predetermined chemical compound or compounds ; and separating said extractant phase from said condensate phase.

In a prefeπed embodiment of the process of the present invention, an internal reference standard is utilized to enable the amount of the predetermined chemical compound or compounds in the initial aqueous sample to be more accurately determined. According to this prefeπed embodiment, a process for extracting a predetermined chemical compound or compounds from an aqueous sample matπx compπses. adding an internal reference standard solution to said aqueous sample matπx; diluting the resulting aqueous sample matnx including said internal reference standard including with a diluent; reacting the diluted aqueous sample matπx with a chemically active substance; boiling the resulting aqueous sample matπx to produce vapors; condensing said vapors to form a condensate, contacting said condensate with an extractant for the predetermined chemical compound or compounds, said extractant being substantially immiscible with said condensate, to extract the predetermined chemical compound or compounds and the internal reference standard from said condensate and produce an extractant phase compnsing the predetermined chemical compound or compounds and the internal reference standard(s), and a condensate phase depleted in the predetermined chemical compound or compounds and the internal reference standard; and separating said extractant phase from said condensate phase. The levels (concentrations) of the predetermined chemical compound or compounds and

the internal reference standard in the extraction phase, which is loaded with the predetermined chemical compound or compounds, may be determined by standard analytical techniques, for example an losotope dilution (HREC/HRDD) assay. The initial concentration of the predetermined chemical compound or compounds in the aqueous sample matnx may then be calculated using the internal reference standard(s) extracted from the aqueous sample matπx.

The diluting and reacting steps of this preferred embodiment of the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matπx. In this embodiment of the process of the present invention a process for extracting a predetermined chemical compound or compounds from an aqueous sample matπx compπses: adding an internal reference standard(s) solution to said aqueous sample matnx; diluting the aqueous sample matnx including said internal reference standard(s) with a diluent composition compnsing a diluent and a chemically active substance which will react with the aqueous sample matπx; boiling the resulting aqueous sample matπx to produce vapors; condensing said vapors to form a condensate, contacting said condensate with an extractant for the predetermined chemical compound or compounds, said extractant being substantially immiscible with said condensate, to extract the predetermined chemical compound or compounds and the internal reference standard(s) from said condensate and produce an extractant phase compnsing the predetermined chemical compound or compounds and the internal reference standard(s), and a condensate phase depleted in the predetermined chemical compound or compounds and the internal reference standard(s) ; and separating said extractant phase from said condensate phase.

A prefeπed aqueous sample matπx is blood, more preferably blood serum, hereafter refeπed to as serum. The serum may be human or of other animal oπgin. Generally, the starting amount of aqueous sample matπx will range from 1 to 10 milliliters, more typically from 2 to 4 milliliters.

Diluents suitable for use in the process of the present invention include, but are not limited to water and water based solutions.

The chemically active substance utilized in the process of the present invention is preferably a substance which will aid in the destruction of sample matπx components which would otherwise interfere with the release of the predetermined chemical compound or compounds into the vapor phase dunng boiling, and/or subsequent extraction of the predetermined chemical compound or compounds from the condensate. The chemically active substance should preferably increase the hydroxide ion

concentration in the aqueous sample matπx (impart alkalinity) preferably in an amount at least equivalent to 0.5 N sodium hydroxide, but not stronger than 2N sodium hydroxide in ability to promote base-catalyzed hydrolysis Suitable chemically active substances include, but are not limited to, an alkali hydroxide, such as sodium hydroxide, potassium hydroxide, cesium hydroxide, or lithium hydroxide A prefeπed chemically active substance is IN potassium hydroxide.

The chemically active substance may be added to the diluent pπor to its addition to the aqueous sample matπx to form a diluent composition which is utilized to dilute and react with the aqueous sample matπx The amount of diluent composition utilized in the process of the present invention should be an amount sufficient to permit the extraction of the predetermined chemical compound or compounds from the aqueous sample matπx. Generally, 100 to 250 milliliters (mL) of diluent composition is utilized per mL of aqueous sample matπx.

Alternatively, the diluent and chemically actι\ e substance may be sequentially added to the aqueous sample matπx. In this case, the total volume of diluent and chemically active substance would also equal 100 to 250 milliliters (mL) of diluent composition per L of aqueous sample matπx

The internal reference standard(s) solution compπses

0.1 to 100 picograms, preferably 1 to 15 picograms, more preferably about 10 picograms of an internal reference standard(s) for the predetermined chemical compound or compounds per millimeter of the sample matnx and less than or equal to 100 microiiters, preferablv 1 to 15 microiiters, more preferably about 10 microiiters of a water-miscible, hydrogen bonding solvent; wherein the internal reference standard(s) for the predetermined chemical compound or compounds is dissolved in the solvent.

Suitable internal reference standards include, but are not limited to, isotopically labeled analogs of the predetermined chemical compound or compounds. Suitable intemal reference standards for the predetermined compound or compounds include, but are not limited to, an isotopically labeled analog(s) of the predetermined compound or compounds such as ¹³ C ₁₂ -2,3,7,8-TCDD; ³⁷ Cl -2,3,7,8-TCDD, ¹³ C ₆ -2,3,7,8-TCDD; ¹³ C ₁₂ -2,3,7,8-PeCDF; ¹³ C ₁₂ -2,3,7,8-TCDF, ¹³ C _{1 2} - l,2,3,7,8-PeCDD; ¹³ C ₁₂ -

1,2,3 ,7,8- PeCDF; ¹³ C ₁₂ -3,3\4,4',5-PCB. Suitable water- iscible, hydrogen bonding solvents include, but are not limited to, methanol, DMSO, acetone, ethanol.

As set forth above, the internal reference standard(s) for the predetermined chemical compound or compounds may be added to the aqueous sample matπx pπor to the dilution of the aqueous sample matπx. In certain cases, an internal reference standard(s) for the predetermined chemical compound or compounds may already be

present in the aqueous sample matπx and therefore an internal reference standard(s) for the predetermined chemical compound or compounds would not need to be added to the aqueous sample matπx.

The addition of an internal reference standard(s) for the predetermined chemical compound or compounds to the aqueous sample matπx, the dilution of the aqueous sample matπx and the reacting of the aqueous sample matπx and the chemically active substance may all be accomplished utilizing standard laboratory equipment and techniques. When necessary, these steps may be earned out while the aqueous sample matnx is under agitation or being stirred. In a prefeπed embodiment of the process of the present invention, the aqueous sample matπx containing an internal reference standard(s) is combined with a diluent composition including a chemically active agent in a flask or vessel which will be utilized to boil the resulting aqueous sample matnx.

The boiling of the resulting aqueous sample matπx to produce vapors may be earned out utilizing standard laboratory equipment and techniques. Generally the resulting aqueous sample matπx is heated in a vessel or flask utilizing a hot plate or other heating element to generate vapors (a vapor phase). A suitable number of ebullition promoting mateπals commonly known as "boiling chips" or "boiling stones" may be added to promote the generation of vapors. Such chips or stones may be of anv type commonly used for such purpose, including but not limited to porcelain, carborundum, or glass

Condensation of the vapor phase (vapors) may be accomplished by captuπng the vapors and allowing the vapors to cool to produce a condensate. In the process of the present invention, after the condensate is contacted with an extractant for the predetermined chemical compound or compounds, the depleted condensate may be recycled back into the boiling aqueous sample matπx

The extractant for the predetermined chemical compound or compounds utilized in the process of the present invention is an extractant which is substantially immiscible with water and capable of extracting the predetermined chemical compound or compounds from an aqueous solution compnsing the predetermined chemical compound or compounds to produce an extractant phase compnsing the predetermined chemical compound or compounds. The extractant for the predetermined chemical compound or compounds preferably should also be capable of extracting the internal reference standard(s), and loading the internal reference standard(s) into the extractant phase, in processes where an internal reference standard(s) is utilized. The extractant for the predetermined chemical compound or compounds should generally have a boiling point of 90° C or greater, preferably of 100° C or greater, so that the extractant does not evaporate at the temperatures where the process is conducted. Any extractant meeting these cπteπa will generally be suitable for use in the process of the present invention.

Depending on the predetermined chemical compound or compounds, suitable extractants may include: 9-carbon containing hydrocarbon solvents (e.g., nonane), isooctane, toluene and tridecane.

The extraction steps of the process of the present invention may be peiformed utilizing commercially available standard laboratory equipment, including condensers and generally available steam distillation equipment.

As set forth above, the predetermined chemical compound or compounds extracted by the process of the present invention may comprise dioxin-like compounds such as: 23,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

23,7,8-tetrachlorodibenzofuran (TCDF)

1 ,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD)

1 ,2,3 ,7,8-pεntachlorodibenzof uran (PeCDF)

2,3, 4,7,8-pentachlorodibenzof uran (PeCDF) 3,3',4,4',5-pentachlorobiphenyl (PCB 126).

Each of these compounds may be extracted utilizing the embodiments of the process of the present invention set forth above. Embodiments of processes of the present invention for extracting each of these compounds are set forth in the following paragraphs. 23.7,8- tetrachlorodibenzo-p-dioxin (TCDD)

According to the present invention, a process for extracting 2,3,7,8- Tetrachlorodibenzo-j>-dioxin (TCDD) from an aqueous sample matrix comprises: diluting the aqueous sample matrix with a diluent; reacting the diluted aqueous sample matrix with a chemically active substance; boiling the resulting aqueous sample matrix to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for TCDD, said extractant being substantially immiscible with said condensate, to extract TCDD and produce an extractant phase comprising TCDD, and a condensate phase depleted in TCDD; and separating said extractant phase from said condensate phase.

The levels (concentration) of TCDD in the TCDD loaded extractant phase may be determined by standard analytical techniques.

The diluting and reacting steps in the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matrix. According to this embodiment of the process of the present invention a process for extracting 2,3,7,8- Tetrachlorodibenzo-2-dioxin (TCDD) from an aqueous sample matrix comprises: diluting the aqueous sample matrix with a diluent composition comprising a

diluent and a chemically active substance which will react with the aqueous sample matnx, boiling the resulting aqueous sample matπx to produce vapors; condensing said vapors to form a condensate, contacting said condensate with an extractant for TCDD, said extractant being substantially immiscible with said condensate, to extract TCDD and produce an extractant phase compnsing TCDD, and a condensate phase depleted in TCDD; and separating said extractant phase from said condensate phase.

In a prefeπed embodiment of the process of the present invention, an internal reference standard(s) is utilized to enable the amount of TCDD in the initial aqueous sample to be more accurately determined. According to this prefeπed embodiment, a process for extracting 2,3,7,8-Tetrachlorodιbenzo-p-dιoxιn (TCDD) from an aqueous sample matnx compπses: adding an internal reference standard(s) solution to said aqueous sample matπx, diluting the resulting aqueous sample matπx including said internal reference standard(s) including with a diluent; reacting the diluted aqueous sample matnx with a chemically active substance; boiling the resulting aqueous sample matπx to produce vapors, condensing said vapors to form a condensate, contacting said condensate with an extractant for TCDD, said extractant being substantially immiscible with said condensate, to extract TCDD and the internal reference standard(s) from said condensate and produce an extractant phase compnsmg TCDD and the internal reference standard(s), and a condensate phase depleted in TCDD and the internal reference standard(s); and separating said extractant phase from said condensate phase.

The levels (concentrations) of TCDD and the internal reference standard(s) in the TCDD loaded extractant phase may be determmed by standard analytical techniques, for example an losotope dilution assay. The initial concentration of TCDD in the aqueous sample matnx may then be calculated using the internal reference standard(s) extracted from the aqueous sample matπx.

The diluting and reacting steps of this preferred embodiment of the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matπx. In this embodiment of the process of the present invention a process for extracting 23,7,8-Tetrachlorodιbenzo-p-dιoxιn (TCDD) from an aqueous sample matπx compπses: adding an internal reference standard(s) solution to said aqueous sample matπx; diluting the aqueous sample matπx including said internal reference standard(s)

with a diluent composition compnsing a diluent and a chemically active substance which will react with the aqueous sample matπx, boiling the resulting aqueous sample matnx to produce vapors, condensing said vapors to form a condensate, contacting said condensate with an extractant for TCDD, said extractant being substantially immiscible with said condensate, to extract TCDD and the internal reference standard(s) from said condensate and produce an extractant phase compnsing TCDD and the internal reference standard(s), and a condensate phase depleted in TCDD and the internal reference standard(s); and separating said extractant phase from said condensate phase

23.7.8-tetrachlorodιbenzofuran (TCDF)

According to the present invention, a process for extracting 2,3,7,8- tetrachlorodi benzofuran (TCDF) from an aqueous sample matnx compπses diluting the aqueous sample matπx with a diluent, reacting the diluted aqueous sample matnx vv ith a chemically active substance, boiling the resulting aqueous sample matnx to produce vapors, condensing said vapors to form a condensate, contacting said condensate with an extractant for TCDF, said extractant being substantially immiscible with said condensate, to extract TCDF and produce an extractant phase compnsmg TCDF, and a condensate phase depleted in TCDF; and separating said extractant phase from said condensate phase The levels (concentration) of TCDF in the TCDF loaded extractant phase may be determined by standard analytical techniques. The diluting and reacting steps in the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matnx. According to this embodiment of the process of the present invention a process for extracting 2,3,7,8- tetrachlorodi benzofuran (TCDF) from an aqueous sample matπx compπses: diluting the aqueous sample matπx with a diluent composition compnsmg a diluent and a chemically active substance which will react with the aqueous sample matπx; boiling the resulting aqueous sample matπx to produce vapors, condensing said vapors to form a condensate, contacting said condensate with an extractant for TCDF, said extractant being substantially immiscible with said condensate, to extract TCDF and produce an extractant phase compnsmg TCDF, and a condensate phase depleted in TCDF; and separating said extractant phase from said condensate phase

In a prefeπed embodiment of the process of the present invention, an intemal reference standard(s) is utilized to enable the amount of TCDF in the initial aqueous sample to be more accurately determined. According to this prefeπed embodiment, a process for extracting 2,3,7,8-tetrachlorodibenzofuran (TCDF) from an aqueous sample matrix comprises: adding an intemal reference standard(s) solution to said aqueous sample matrix; diluting the resulting aqueous sample matrix including said intemal reference standard(s) including with a diluent; reacting the diluted aqueous sample matrix with a chemically active substance; boiling the resulting aqueous sample matrix to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for TCDF, said extractant being substantially immiscible with said condensate, to extract TCDF and the intemal reference standard(s) from said condensate and produce an extractant phase comprising TCDF and the intemal reference standard(s), and a condensate phase depleted in TCDF and the intemal reference standard(s); and separating said extractant phase from said condensate phase. The levels (concentrations) of TCDF and the intemal reference standard(s) in the TCDF loaded extractant phase may be determined by standard analytical techniques, for example an iosotope dilution assay. The initial concentration of TCDF in the aqueous sample matrix may then be calculated using the intemal reference standard(s) extracted from the aqueous sample matrix.

The diluting and reacting steps of this prefeπed embodiment of the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matrix. In this embodiment of the process of the present invention a process for extracting 2,3, 7,8-tetrachlorodibenzof uran (TCDF) from an aqueous sample matrix comprises: adding an intemal reference standard(s) solution to said aqueous sample matrix; diluting the aqueous sample matrix including said intemal reference standard(s) with a diluent composition comprising a diluent and a chemically active substance which will react with the aqueous sample matrix; boiling the resulting aqueous sample matrix to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for TCDF, said extractant being substantially immiscible with said condensate, to extract TCDF and the intemal reference standard(s) from said condensate and produce an extractant phase comprising TCDF and the intemal reference standard(s), and a condensate phase depleted in TCDF and the

internal reference standard(s); and separating said extractant phase from said condensate phase.

1.23.7,8- pentachlorodibenzo-p-dioxin (PeCDD) According to the present invention, a process for extracting 1,2,3,7,8- pentachlorodibenzo-p-dioxin (PeCDD) from an aqueous sample matπx compπses: diluting the aqueous sample matπx with a diluent; reacting the diluted aqueous sample matπx with a chemically active substance; boiling the resulting aqueous sample matnx to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for PeCDD, said extractant being substantially immiscible with said condensate, to extract PeCDD and produce an extractant phase compnsmg PeCDD, and a condensate phase depleted in PeCDD; and separating said extractant phase from said condensate phase The levels (concentration) of PeCDD in the PeCDD loaded extractant phase may be determined by standard analytical techniques.

The diluting and reacting steps in the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matπx. According to this embodiment of the process of the present invention a process for extracting 1,2,3,7,8-pentachlorodιbenzo-p-dιoxιn (PeCDD) from an aqueous sample matπx compπses: diluting the aqueous sample matπx with a diluent composition compnsing a diluent and a chemically active substance which will react with the aqueous sample matπx; boiling the resulting aqueous sample matπx to produce vapors, condensing said vapors to form a condensate; contacting said condensate with an extractant for PeCDD, said extractant being substantially immiscible with said condensate, to extract PeCDD and produce an extractant phase compns g PeCDD, and a condensate phase depleted in PeCDD; and separating said extractant phase from said condensate phase.

In a prefeπed embodiment of the process of the present invention, an internal reference standard(s) is utilized to enable the amount of PeCDD in the initial aqueous sample to be more accurately determined. According to this prefeπed embodiment, a process for extracting 1,2,3,7,8-pentachlorodιbenzo-p-dιoxιn (PeCDD) from an aqueous sample matπx compπses: adding an internal reference standard(s) solution to said aqueous sample matπx, diluting the resulting aqueous sample matπx including said intemal reference

standard(s) including with a diluent; reacting the diluted aqueous sample matπx with a chemically active substance; boiling the resulting aqueous sample matπx to produce vapors, condensing said vapors to form a condensate; contacting said condensate with an extractant for PeCDD, said extractant being substantially immiscible with said condensate, to extract PeCDD and the internal reference standard(s) from said condensate and produce an extractant phase compnsing PeCDD and the internal reference standard(s), and a condensate phase depleted in PeCDD and the internal reference standard(s); and separating said extractant phase from said condensate phase

The levels (concentrations) of PeCDD and the internal reference standard(s) in the PeCDD loaded extractant phase may be determined by standard analytical techmques, for example an iosotope dilution assay. The initial concentration of PeCDD in the aqueous sample matπx may then be calculated using the internal reference standard(s) extracted from the aqueous sample matπx.

The diluting and reacting steps of this prefeπed embodiment of the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matπx. In this embodiment of the process of the present invention a process for extracting 1,23,7,8-pentachlorodιbenzo-p-dιoxιn (PeCDD) from an aqueous sample matπx compπses: adding an internal reference standard(s) solution to said aqueous sample matπx; diluting the aqueous sample matπx including said internal reference standard(s) with a diluent composition compnsing a diluent and a chemically active substance which will react with the aqueous sample matπx; boiling the resulting aqueous sample matπx to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for PeCDD, said extractant being substantially immiscible with said condensate, to extract PeCDD and the internal reference standard(s) from said condensate and produce an extractant phase compnsing PeCDD and the internal reference standard(s), and a condensate phase depleted in PeCDD and the internal reference standard(s); and separating said extractant phase from said condensate phase.

1 ,23,7,8-pentachlorodιbenzofuran

According to the present invention, a process for extracting 1,2,3,7,8- pentachlorodi benzofuran from an aqueous sample matπx compπses: diluting the aqueous sample matπx with a diluent;

reacting the diluted aqueous sample matπx with a chemically active substance, boiling the resulting aqueous sample matnx to produce vapors, condensing said vapors to form a condensate, contacting said condensate with an extractant for 1,2,3,7,8- pen tachlorodi benzofuran, said extractant being substantially immiscible with said condensate, to extract 1,23, 7,8- pentachlorodi benzofuran and produce an extractant phase compnsing 1,2,3,7,8-pentachlorodιbenzofuran, and a condensate phase depleted in 1, 2,3, 7,8-pentachlorodιbenzof uran; and separating said extractant phase from said condensate phase The levels (concentration) of 1,2,3,7,8-pentachlorodι benzofuran in the 1,2,3,7,8- pentachlorodi benzofuran loaded extractant phase mav be determined by standard analytical techniques

The diluting and reacting steps in the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matπx. According to this embodiment of the process of the present invention a process for extracting 1,23,7,8-pentachlorodιbenzo-p-dιoxιn (1,2,3 ,7,8-pentachlorodιbenzofuran) from an aqueous sample matπx compπses- diluting the aqueous sample matπx with a diluent composition compnsing a diluent and a chemically active substance which will react with the aqueous sample matnx; boiling the resulting aqueous sample matπx to produce vapors, condensing said vapors to form a condensate, contacting said condensate with an extractant for 1,2,3,7,8- pentachlorodi benzofuran, said extractant being substantially immiscible with said condensate, to extract 1,23, 7,8- pentachlorodi benzofuran and produce an extractant phase compnsing 1,2,3,7,8-pentachlorodιbenzofuran, and a condensate phase depleted in 1,2,3,7,8-pentachlorodιbenzofuran, and separating said extractant phase from said condensate phase. In a prefeπed embodiment of the process of the present invention, an internal reference standard(s) is utilized to enable the amount of 1,2,3,7,8- pen tachlorodi benzofuran in the initial aqueous sample to be more accurately determined According to this prefeπed embodiment, a process for extracting 1,2,3,7,8- pentachlorodibenzo-p-dioxin (1,2,3,7,8-pentachlorodιbenzofuran) from an aqueous sample matπx compπses: adding an internal reference standard(s) solution to said aqueous sample matπx; diluting the resulting aqueous sample matπx including said intemal reference standard(s) including with a diluent;

reacting the diluted aqueous sample matrix with a chemically active substance; boiling the resulting aqueous sample matrix to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for 1,23,7,8- pentachlorodi benzofuran, said extractant being substantially immiscible with said condensate, to extract 1,23,7,8-pentachlorodibenzofuran and the intemal reference standard(s) from said condensate and produce an extractant phase comprising 1,2,3,7,8- pentachlorodi benzofuran and the intemal reference standard(s), and a condensate phase depleted in 1,2,3,7,8-pentachlorodibenzofuran and the intemal reference standard(s); and separating said extractant phase from said condensate phase.

The levels (concentrations) of 1,2,3,7,8-pentachlorodibenzofuran and the intemal reference standard(s) in the 1, 2,3, 7,8-pentachlorodi benzofuran loaded extractant phase may be determined by standard analytical techniques, for example an iosotope dilution assay. The initial concentration of 1, 2,3, 7,8-pentachlorodi benzofuran in the aqueous sample matrix may then be calculated using the intemal reference standard(s) extracted from the aqueous sample matrix.

The diluting and reacting steps of this prefeπed embodiment of the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matrix. In this embodiment of the process of the present invention a process for extracting 1,2,3,7,8-pentachlorodibenzo-p-dioxin ( 1 ,2,3, 7,8-pentachIorodibenzof uran) from an aqueous sample matrix comprises: adding an intemal reference standard(s) solution to said aqueous sample matrix; diluting the aqueous sample matrix including said intemal reference standard(s) with a diluent composition comprising a diluent and a chemically active substance which will react with the aqueous sample matrix; boiling the resulting aqueous sample matrix to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for 1,23,7,8- pentachlorodi benzofuran, said extractant being substantially immiscible with said condensate, to extract 1,23 ,7,8- pentachlorodi benzofuran and the intemal reference standard(s) from said condensate and produce an extractant phase comprising 1,2,3,7,8- pen tachlorodi benzofuran and the intemal reference standard(s), and a condensate phase depleted in 1,2,3,7,8-ρentachlorodibenzofuran and the intemal reference standard(s); and separating said extractant phase from said condensate phase.

2.3.4.7.8- pentachlorodi benzofuran

According to the present invention, a process for extracting 2,3,4,7,8-

pentachlorodibenzofuran from an aqueous sample matπx compπses. diluting the aqueous sample matπx with a diluent; reacting the diluted aqueous sample matπx with a chemically active substance, boiling the resulting aqueous sample matπx to produce vapors, condensing said vapors to form a condensate; contacting said condensate with an extractant for 2,3,4,7,8- pen tachlorodi benzofuran, said extractant being substantially immiscible with said condensate, to extract 2,3 ,4,7 ,8-pentachlorodι benzofuran and produce an extractant phase compnsing 2,3 ,4,7,8-pentachlorodιbenzol uran, and a condensate phase depleted in 2,3,4,7,8-pentachlorodιbenzofuran; and separating said extractant phase from said condensate phase The levels (concentration) of 2,3,4,7,8-pentachlorodιbenzofuran in the 2,3,4,7,8- pentachlorodi benzofuran loaded extractant phase may be determined by standard analytical techniques. The diluting and reacting steps in the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matπx. According to this embodiment of the process of the present invention a process for extracting 2,3,4,7,8-pentachlorodιbenzofuran from an aqueous sample matnx compnses diluting the aqueous sample matπx with a diluent composition compnsing a diluent and a chemically active substance which will react with the aqueous sample matπx; boiling the resulting aqueous sample matnx to produce vapors, condensing said vapors to form a condensate, contacting said condensate with an extractant for 2,3,4,7,8- pen tachlorodi benzofuran, said extractant being substantially immiscible with said condensate, to extract 2,3, 4,7,8- pentachlorodi benzofuran and produce an extractant phase compnsing 2,3,4,7,8-pentachlorodιbenzofuran, and a condensate phase depleted in 23,4,7,8-pentachlorodιbenzofuran; and separating said extractant phase from said condensate phase

In a prefeπed embodiment of the process of the present invention, an internal reference standard(s) is utilized to enable the amount of 2,3 ,4,7,8- pentachlorodibenzofuran in the initial aqueous sample to be more accurately determined. According to this prefeπed embodiment, a process for extracting 2,3,4,7,8- pentachlorodi benzofuran from an aqueous sample matπx compπses: adding an internal reference standard(s) solution to said aqueous sample matnx; diluting the resulting aqueous sample matπx including said internal reference standard(s) including with a diluent;

reacting the diluted aqueous sample matnx with a chemically active substance; boiling the resulting aqueous sample matπx to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for 2,3,4,7,8- pentachlorodibenzofuran, said extractant being substantially immiscible with said condensate, to extract 2,3, 4,7,8-pen tachlorodi benzofuran and the internal reference standard(s) from said condensate and produce an extractant phase compnsing 2,3,4,7,8- pentachlorodibenzofuran and the internal reference standard(s), and a condensate phase depleted in 2,3,4,7 ,8-pentachlorodι benzofuran and the internal reference standard(s); and separating said extractant phase from said condensate phase.

The levels (concentrations) of 2,3,4,7,8-pentachlorodιbenzofuran and the internal reference standard(s) in the 23, 4,7,8-pentachlorodι benzofuran loaded extractant phase may be determined by standard analytical techniques, for example an iosotope dilution assay The initial concentration of 2,3,4,7,8-pentachlorodιbenzofuran in the aqueous sample matπx may then be calculated using the internal reference standard(s) extracted from the aqueous sample matπx.

The diluting and reacting steps of this prefeπed embodiment of the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matπx. In this embodiment of the process of the present invention a process for extracting 2,3 ,4,7,8-pentachlorodι benzofuran from an aqueous sample matπx compπses: adding an internal reference standard(s) solution to said aqueous sample matπx; diluting the aqueous sample matπx including said internal reference standard(s) with a diluent composition compns g a diluent and a chemically active substance which will react with the aqueous sample matπx; boiling the resulting aqueous sample matπx to produce vapors, condensing said vapors to form a condensate; contacting said condensate with an extractant for 2,3,4,7,8- pentachlorodibenzofuran, said extractant being substantially immiscible with said condensate, to extract 2,3,4,7,8-pentachlorodιbenzofuran and the internal reference standard(s) from said condensate and produce an extractant phase compnsing 2,3,4,7,8- pentachlorodi benzofuran and the internal πeference standard(s), and a condensate phase depleted in 2,3 ,4,7,8-pen tachlorodi benzof uran and the internal reference standard(s); and separating said extractant phase from said condensate phase.

33'.4.4'.5-pentachlorobiphenyl (PCB 126)

According to the present invention, a process for extracting 33 ',4,4', 5- pentachlorobi phenyl (PCB 126) from an aqueous sample matπx compπses:

diluting the aqueous sample matrix with a diluent; reacting the diluted aqueous sample matrix with a chemically active substance; boiling the resulting aqueous sample matrix to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for PCB 126, said extractant being substantially immiscible with said condensate, to extract PCB 126 and produce an extractant phase comprising PCB 126, and a condensate phase depleted in PCB 126; and separating said extractant phase from said condensate phase. The levels (concentration) of PCB 126 in the PCB 126 loaded extractant phase may be determined by standard analytical techniques.

The diluting and reacting steps in the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matrix. According to this embodiment of the process of the present invention a process for extracting 3,3',4,4',5-pentachlorobiphenyl (PCB 126) from an aqueous sample matrix comprises: diluting the aqueous sample matrix with a diluent composition comprising a diluent and a chemically active substance which will react with the aqueous sample matrix; boiling the resulting aqueous sample matrix to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for PCB 126, said extractant being substantially immiscible with said condensate, to extract PCB 126 and produce an extractant phase comprising PCB 126, and a condensate phase depleted in PCB 126; and separating said extractant phase from said condensate phase. In a prefeπed embodiment of the process of the present invention, an intemal reference standard(s) is utilized to enable the amount of PCB 126 in the initial aqueous sample to be more accurately determined. According to this prefeπed embodiment, a process for extracting 33',4,4',5-pentachlorobiphenyl (PCB 126) from an aqueous sample matrix comprises: adding an intemal reference standard(s) solution to said aqueous sample matrix; diluting the resulting aqueous sample matrix including said intemal reference standard(s) including with a diluent; reacting the diluted aqueous sample matrix with a chemically active substance; boiling the resulting aqueous sample matrix to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for PCB 126, said extractant being substantially immiscible with said condensate, to extract PCB 126 and the intemal reference standard(s) from said condensate and produce an extractant phase comprising

PCB 126 and the internal reference standard(s), and a condensate phase depleted in PCB 126 and the internal reference standard(s); and separating said extractant phase from said condensate phase The levels (concentrations) of PCB 126 and the internal reference standard(s) in the PCB 126 loaded extractant phase may be determined by standard analytical techniques, for example an iosotope dilution assay. The initial concentration of PCB 126 in the aqueous sample matπx may then be calculated using the intemal reference standard(s) extracted from the aqueous sample matnx.

The diluting and reacting steps of this prefeπed embodiment of the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matπx. In this embodiment of the process of the present invention a process for extracting 3,3 ',4,4', 5- pentachlorobiphenyl (PCB 126) from an aqueous sample matnx compnses: adding an internal reference standard(s) solution to said aqueous sample matπx; diluting the aqueous sample matπx including said internal reference standard(s) with a diluent composition compnsing a diluent and a chemically active substance which will react with the aqueous sample matnx, boiling the resulting aqueous sample matnx to produce vapors, condensing said vapors to form a condensate, contacting said condensate with an extractant for PCB 126, said extractant being substantially immiscible with said condensate, to extract PCB 126 and the internal reference standard(s) from said condensate and produce an extractant phase compnsing PCB 126 and the internal reference standard(s), and a condensate phase depleted in PCB 126 and the internal reference standard(s); and separating said extractant phase from said condensate phase.

In addition to extracting the dioxin-hke compounds set forth in the preceding sections individually, the process of the present invention may also be utilized to extract combinations of dioxin- ke compounds substantially simultaneously from a fluid sample. According to the present invention, a process for extracting a predetermined chemical compound compnsing 2,3,7,8-tetrachlorodιbenzo-p-dιoxιn (TCDD); 2,3,7,8-tetrachlorodιbenzofuran (TCDF); 1,23,7,8-pentachlorodιbenzo-p- dioxin (PeCDD); 1,2,3,7,8-pentachlorodιbenzofuran, 2,3,4,7,8- pentachlorodibenzofuran; 3,3',4,4',5-pentachlorobιphenyl (PCB 126) and/or mixtures thereof from an aqueous sample matnx compnses: diluting the aqueous sample matπx with a diluent; reacting the diluted aqueous sample matπx with a chemically active substance,

boiling the resulting aqueous sample matrix to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for the predetermined chemical compound , said extractant being substantially immiscible with said condensate, to extract the predetermined chemical compound and produce an extractant phase comprising the predetermined chemical compound , and a condensate phase depleted in the predetermined chemical compound ; and separating said extractant phase from said condensate phase. The levels (concentration) of the predetermined chemical compound in the predetermined chemical compound loaded extractant phase may be determined by standard analytical techniques.

The diluting and reacting steps in the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matrix. According to this embodiment of the process of the present invention a process for extracting a predetermined chemical compound comprising 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); 2,3, 7,8-tetrachlorodi benzofuran (TCDF); 1,23,7,8-pentachlorodibenzo-p- dioxin (PeCDD);

1, 2,3 ,7,8-pentachlorodi benzofuran; 2,3,4,7,8-pentachlorodibenzofuran; 3,3',4,4',5- pentachlorobiphenyl (PCB 126) and/or mixtures thereof from an aqueous sample matrix comprises: diluting the aqueous sample matrix with a diluent composition comprising a diluent and a chemically active substance which will react with the aqueous sample matrix; boiling the resulting aqueous sample matrix to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for the predetermined chemical compound , said extractant being substantially immiscible with said condensate, to extract the predetermined chemical compound and produce an extractant phase comprising the predetermined chemical compound , and a condensate phase depleted in the predetermined chemical compound ; and separating said extractant phase from said condensate phase.

In a prefeπed embodiment of the process of the present invention, an intemal reference standard(s) is utilized to enable the amount of the predetermined chemical compound in the initial aqueous sample to be more accurately determined. According to this prefeπed embodiment, a process for extracting a predetermined chemical compound comprising 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); 23,7,8- tetrachlorodibenzofuran (TCDF); 1,23,7,8-ρentachlorodibenzo-p-dioxin (PeCDD);

1,2,3,7,8-pentachlorodιbenzofuran; 2,3,4,7,8-pentachlorodιbenzofuran; 3,3 \4,4',5- pentachlorobiphenyl (PCB 126) and/or mixtures thereof from an aqueous sample matnx compnses: adding an internal reference standard(s) solution to said aqueous sample matnx; diluting the resulting aqueous sample matπx including said intemal reference standard(s) including with a diluent; reacting the diluted aqueous sample matπx with a chemically active substance; boiling the resulting aqueous sample matπx to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for the predetermined chemical compound , said extractant being substantially immiscible with said condensate, to extract the predetermined chemical compound and the internal reference standard(s) from said condensate and produce an extractant phase compnsmg the predetermined chemical compound and the internal reference standard(s), and a condensate phase depleted in the predetermined chemical compound and the intemal reference standard(s) ; and separating said extractant phase from said condensate phase. The levels (concentrations) of the predetermined chemical compound and the internal reference standard(s) in the predetermined chemical compound loaded extractant phase may be determined by standard analytical techniques, for example an iosotope dilution assay. The initial concentration of the predetermined chemical compound in the aqueous sample matπx may then be calculated using the intemal reference standard(s) extracted from the aqueous sample matπx.

The diluting and reacting steps of this prefeπed embodiment of the process of the present invention may be combined by adding the chemically active substance to the diluent to produce a diluent composition which is added to and reacts with the aqueous sample matπx. In this embodiment of the process of the present invention a process for extracting a predetermined chemical compound compnsing 2,3,7,8-tetrachlorodιbenzo-p- dioxm (TCDD); 2,3,7,8-tetrachlorodιbenzofuran (TCDF), 1,23,7,8- pentachlorodibenzo-p-dioxin (PeCDD); 1,2,3,7,8-pentachlorodιbenzofuran, 2,3,4,7,8- pentachlorodibenzofuran; 3,3',4,4',5-pentachlorobιphenyl (PCB 126) and/or mixtures thereof from an aqueous sample matnx compnses- adding an internal reference standard(s) solution to said aqueous sample matnx; diluting the aqueous sample matπx including said internal reference standard(s) with a diluent composition compnsmg a diluent and a chemically active substance which will react with the aqueous sample matnx; boiling the resulting aqueous sample matπx to produce vapors; condensing said vapors to form a condensate; contacting said condensate with an extractant for the predetermined chemical

compound , said extractant being substantially immiscible with said condensate, to extract the predetermined chemical compound and the internal reference standard(s) from said condensate and produce an extractant phase compnsing the predetermined chemical compound and the internal reference standard(s), and a condensate phase depleted in the predetermined chemical compound and the intemal reference standard(s) ; and separating said extractant phase from said condensate phase.

An embodiment of the process of the present invention for extracting TCDD is depicted schematically in Figure 1. With reference to Figure 1, in an embodiment of the process of the present invention an Intemal Reference standard(s) for TCDD in solution is added to a blood serum sample. The intemal reference standard(s) containing serum sample, and a diluent composition compnsing NaOH as a chemically active substance are admixed in a boiling vessel. A suitable number of "boiling chips" or "boiling stones" are added, the number being unspecified but commonly familiar to anyone generally expenenced with the simple art of distillation to the boiling vessel.

The boiling vessel is connected to an apparatus, such as those commercially available, that permits the solution in the boiling vessel to be boiled to produce vapors. The vapors generated compnse TCDD and the internal reference standard(s) and are captured and condensed to form a condensate The condensate passes through an organic extractant for TCDD which is substantially immiscible with the condensate. The organic extractant dissolves and extracts TCDD and the internal reference standard(s) from the condensate to produce an extract phase loaded with TCDD and the internal reference standard(s), and a TCDD (and internal reference standard(s)) depleted condensate. The depleted condensate is recycled to the boiling vessel. The organic extractant selected is one which does not evaporate from the apparatus duπng the applica¬ tion of heat to the boiling vessel. In addition the organic extractant does not enter the vessel in which boiling proceeds.

Suitable apparatuses for conducting the depicted process are widely available from suppliers of laboratory glassware and include those known to those of ordinary skill in the art of steam distillation.

According to the process of the present invention, boiling of the diluted serum solution containing internal standard and chemically active substances is continued until the TCDD has been transfeπed into the organic extractant to an extent acceptable to the operator. In the interests of rapid sample processing this time should not exceed one hour, and is pπmaπly determined by the rate at which heat is applied to the containment vessel. A typical time of boiling would be 45 minutes

At the end of the boiling peπod heat is no longer applied to the boiling vessel The organic extractant is removed from the apparatus and concentrated by evaporation to

an amount appropnate for its utilization in whatever analytical determination procedure is selected. Concentration of the organic solvent containing TCDD may be accomplished by any conventional means, including but not limited to the use of an evaporator, steam bath, or the like. Analytical determination of the TCDD in the organic solvent deπved from the descπbed procedure may be performed by any means offeπng adequate sensitivity and specificity.

Similar process steps may be utilized to extract and punfy other dioxin-like compounds such as those listed above. The features and advantages of the process of the present invention are further illustrated by the following example.

Example

An embodiment of the process of the present invention was performed to illustrate the advantageous recovery of TCDD from a 2mL human blood serum sample having a known concentration of TCDD of 500 femtograms of TCDD per milliliter

An internal reference standard(s) for TCDD, which in this example was a 0.02

13 mL solution of 2 picograms of C ₁₂ -2,3,7,8-TCDD in methanol, was added to the 2 mL serum sample. 500 mL of 1.0N NaOH diluent solution, compnsmg NaOH as a chemically active substance were mixed with the internal reference standard(s) containing semm sample in a 1-Liter boiling vessel suitable for reflux or distillation conditions 6 to 8 carborundum "boiling chips" were also added to the boiling vessel.

The boiling vessel containing the admixed solution was connected to a commercially available microsteam distillation apparatus that permitted the solution to be boiled, under such conditions that the vapors therefrom were condensed back to the liquid state to form a condensate The condensed liquid passed through 1 mL of isooctane (an organic extractant capable of dissolving TCDD but substantially immiscible with the condensate) which extracted TCDD and the internal reference standard(s) to form an extractant phase compnsmg TCDD and the internal reference standard(s) The TCDD depleted condensate liquid thereafter returned to the boiling vessel.

Boiling was continued for 45 minutes. At the end of the boiling penod heat was no longer applied to the boiling vessel. The extractant phase compnsmg the TCDD and internal reference standard(s) was removed from the apparatus and concentrated in a vacuum centπfuge. A combination of gas chromatography with mass spectrometry was utilized to generate the graphs illustrated in Figure 2. These results illustrate that the process of the invention extracted a TCDD with sufficient recovery and degree of freedom from interferences for measurement of TCDD initially at a concentration of 0.5 parts per

tπllion (0.5 picograms of TCDD per gram of semm).

As descπbed above, and shown by the example embodiment, the process of the present invention provides the following advantages: transfer of TCDD from the semm to an organic solvent in less than one hour with no additional punfication of TCDD required; chemical conversion of substances typically found in semm from substances that would otherwise have co-steam distilled with the TCDD or reduced its ability to be steam distilled, into substances that do not have such properties, and the facile modification of the organic solvent solution of TCDD into a form suitable for analytical determination (quantification).

It will thus be seen that the advantages set forth, among those made apparent from the preceding descπption, are efficiently obtained by the process of the present invention. Since certain changes may be made in carrying out the above embodiments of the process, without departing from the spiπt and scope of the invention, it is intended that all matter contained in the above descπption shall be inteφreted as illustrative and not in a limiting sense.