Pretreatment method for analyzing dioxin compounds and analytical method using the same

Abstract

A pretreatment method for analyzing dioxin compounds and an analytical method using the same, in which a column packed with polymer beads that are capable of selectively adsorbing dioxin compounds is used in a purification step during pretreatment, thereby remarkably reducing a time required for pretreatment and improving a recovery rate of an internal standard for purification, are provided.

Claims

1. A pretreatment method for analyzing dioxin compounds, the method comprising the steps of: 1) obtaining a liquid extract including dioxin compounds from a sample; 2) adsorbing the dioxin compounds onto polymer beads by passing the liquid extract through a column packed with the polymer beads; 3) removing substances which are not adsorbed onto the polymer beads by passing a first solvent through the column packed with the dioxin compound-adsorbed polymer beads; and 4) obtaining an eluate including dioxin compounds which are eluted in a second solvent by passing the second solvent through the column packed with polymer beads from which the unadsorbed substances have been removed, wherein the polymer beads are porous particles including one or more hydrophobic repeating units derived from a vinyl aromatic monomer having a non-polar functional group and one or more hydrophilic repeating units derived from a vinyl aromatic monomer having a polar functional group, and wherein the polymer beads further include one or more hydrophilic repeating units represented by the following Chemical Formula 3: ##STR00007## wherein, in Chemical Formula 3, R.sub.9 is hydrogen or a C.sub.1-4 alkyl, A is a substituted or unsubstituted C.sub.2-60 heteroaromatic cyclic group including one or more heteroatoms selected from the group consisting of N, O, and S; or a substituted or unsubstituted C.sub.2-60 hetero-non-aromatic cyclic group including one or more heteroatoms selected from the group consisting of N, O, and S, and 1 is 100 to 10,000.

2. The pretreatment method for analyzing dioxin compounds of claim 1, wherein the dioxin compounds are polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), or a combination thereof.

3. The pretreatment method for analyzing dioxin compounds of claim 1, wherein extraction of the liquid extract is performed by liquid-liquid extraction, solid phase extraction, Soxhlet extraction, or a combination thereof.

4. The pretreatment method for analyzing dioxin compounds of claim 1, wherein the polymer beads include the hydrophobic repeating unit and the hydrophilic repeating unit at a molar ratio of 99:1 to 40:60.

5. The pretreatment method for analyzing dioxin compounds of claim 1, wherein the hydrophobic repeating unit derived from the vinyl aromatic monomer having the non-polar functional group is represented by the following Chemical Formula 1: ##STR00008## wherein, in Chemical Formula 1, R.sub.1 is hydrogen or a C.sub.1-4 alkyl, R.sub.2 is a halogen; a substituted or unsubstituted C.sub.1-20 alkyl; a substituted or unsubstituted C.sub.2-20 alkenyl; a substituted or unsubstituted C.sub.2-20 alkynyl; a substituted or unsubstituted C.sub.3-20 cycloalkyl; a substituted or unsubstituted C.sub.6-20 aryl; or a substituted or unsubstituted C.sub.7-20 aralkyl, a is an integer of 0 to 5, and n is 100 to 10,000.

6. The pretreatment method for analyzing dioxin compounds of claim 1, wherein the hydrophilic repeating unit derived from the vinyl aromatic monomer having the polar functional group is represented by the following Chemical Formula 2: ##STR00009## in Chemical Formula 2, R.sub.3 is hydrogen or a C.sub.1-4 alkyl, R.sub.4 is a polar functional group; a halogen; a substituted or unsubstituted C.sub.1-20 alkyl; a substituted or unsubstituted C.sub.2-20 alkenyl; a substituted or unsubstituted C.sub.2-20 alkynyl; a substituted or unsubstituted C.sub.3-20 cycloalkyl; a substituted or unsubstituted C.sub.6-20 aryl; a substituted or unsubstituted C.sub.7-20 arylalkyl; or a C.sub.7-20 alkylaryl, provided that at least one R.sub.4 is a polar functional group, b is an integer of 1 to 5, and m is 100 to 10,000.

7. The pretreatment method for analyzing dioxin compounds of claim 1, wherein the polar functional group is selected from the group consisting of the following functional groups: —R.sub.5OH, —R.sub.5OR.sub.6, —OR.sub.6, —OC(O)OR.sub.6, —R.sub.5OC(O)OR.sub.6, —C(O)OR.sub.6, —R.sub.5C(O)OR.sub.6, —C(O)R.sub.6, —R.sub.5C(O)R.sub.6, —OC(O)R.sub.6, —R.sub.5OC(O)R.sub.6, —(R.sub.5O).sub.p—OR.sub.6, —(OR.sub.5).sub.p—OR.sub.6, —C(O)—O—C(O)R.sub.6, —R.sub.5C(O)—O—C(O)R.sub.6, —SR.sub.6, —R.sub.5SR.sub.6, —SSR.sub.6, —R.sub.5SSR.sub.6, —S(═O)R.sub.6, —R.sub.5S(═O)R.sub.6, —R.sub.5C(═S)R.sub.6, —R.sub.5C(═S)SR.sub.6, —R.sub.5SO.sub.3R.sub.6, —SO.sub.3R.sub.6, —R.sub.5N═C═S, —N═C═S, —NCO, —R.sub.5—NCO, —CN, —R.sub.5CN, —NNC(═S)R.sub.6, —R.sub.5NNC(═S)R.sub.6, —NO.sub.2, —R.sub.5NO.sub.2, ##STR00010## ##STR00011## ##STR00012## wherein, in the above polar functional groups, each p is independently an integer of 1 to 10, R.sub.5 is a substituted or unsubstituted C.sub.1-20 alkylene; a substituted or unsubstituted C.sub.2-20 alkenylene; a substituted or unsubstituted C.sub.2-20 alkynylene; a substituted or unsubstituted C.sub.3-20 cycloalkylene; a substituted or unsubstituted C.sub.6-20 arylene; a substituted or unsubstituted C.sub.7-20 ararylene; a substituted or unsubstituted C.sub.1-20 alkoxylene; or a substituted or unsubstituted C.sub.1-20 carbonyloxylene, and R.sub.6, R.sub.7, and R.sub.8 are each independently hydrogen; a halogen; a substituted or unsubstituted C.sub.1-20 alkyl; a substituted or unsubstituted C.sub.2-20 alkenyl; a substituted or unsubstituted C.sub.2-20 alkynyl; a substituted or unsubstituted C.sub.3-20 cycloalkyl; a substituted or unsubstituted C.sub.6-20 aryl; a substituted or unsubstituted C.sub.7-20 aralkyl; a substituted or unsubstituted C.sub.1-20 alkoxy; or a substituted or unsubstituted C.sub.1-20 carbonyloxy.

8. The pretreatment method for analyzing dioxin compounds of claim 1, wherein in Chemical Formula 3, A is a substituted or unsubstituted pyrrolyl; a substituted or unsubstituted imidazolyl; a substituted or unsubstituted pyrazolyl; a substituted or unsubstituted pyridinyl; a substituted or unsubstituted pyrazinyl; a substituted or unsubstituted pyrimidinyl; a substituted or unsubstituted pyridazinyl; a substituted or unsubstituted oxazolyl; a substituted or unsubstituted thiazolyl; a substituted or unsubstituted isothiazolyl; a substituted or unsubstituted pyrrolidonyl; a substituted or unsubstituted morpholinyl; a substituted or unsubstituted oxazolidinonyl; or a substituted or unsubstituted caprolactamyl.

9. The pretreatment method for analyzing dioxin compounds of claim 1, wherein the polymer beads each are a copolymer including one kind of the hydrophobic repeating unit derived from the vinyl aromatic monomer having the non-polar functional group and one kind of the hydrophilic repeating unit derived from the vinyl aromatic monomer having the polar functional group; a terpolymer including two kinds of the hydrophobic repeating units derived from the vinyl aromatic monomer having the non-polar functional group and one kind of the hydrophilic repeating unit derived from the vinyl aromatic monomer having the polar functional group; or a terpolymer including one kind of the hydrophobic repeating unit derived from the vinyl aromatic monomer having the non-polar functional group and two kinds of the hydrophilic repeating units derived from the vinyl aromatic monomer having the polar functional group.

10. The pretreatment method for analyzing dioxin compounds of claim 1, wherein the polymer beads are each one or more selected from the group consisting of a polystyrene-polyvinylphenol copolymer, a polystyrene-polyvinylphenylmethanol copolymer, a polydivinylbenzene-polyvinylphenol copolymer, a polydivinylbenzene-polyvinylphenylmethanol copolymer, a polystyrene-polydivinylbenzene-polyvinylphenol terpolymer, and a polystyrene-polydivinylbenzene-polyvinylphenylmethanol terpolymer.

11. The pretreatment method for analyzing dioxin compounds of claim 1, wherein the polymer beads have an average particle size of 10 μm to 100 μm.

12. The pretreatment method for analyzing dioxin compounds of claim 1, wherein the first solvent is one or more selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, ethyl acetate, tetrahydrofuran (THF), dichloromethane, acetone, and acetonitrile.

13. The pretreatment method for analyzing dioxin compounds of claim 1, wherein the second solvent is one or more selected from the group consisting of toluene, hexane, benzene, diethyl ether, and chloroform.

14. The pretreatment method for analyzing dioxin compounds of claim 1, further comprising, between the steps 1) and 2), the steps of: adding an internal standard for purification to the liquid extract; and concentrating the liquid extract to which the internal standard for purification is added.

15. The pretreatment method for analyzing dioxin compounds of claim 1, further comprising, after the step 4), the steps of: concentrating the eluate; and adding an internal standard for syringe addition to the concentrated eluate.

16. An analytical method for dioxin compounds, the method comprising the step of performing instrumental analysis of a sample which is pretreated by the pretreatment method of claim 1.

17. The analytical method for dioxin compounds of claim 16, wherein the instrumental analysis is performed by gas chromatography/high-resolution mass spectrometry.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 illustrates an analytical method for dioxins and furans in a wastewater sample according to the Official Method of Persistent Organic Pollutants announced by the Ministry of Environment in 2007;

(2) FIG. 2 shows results of SEM analysis of polymer bead 1 prepared in Preparation Example 1, polymer bead 2 prepared in Preparation Example 2, and C.sub.18 bead used in Comparative Example 1;

(3) FIG. 3 shows a comparison of recovery rates of internal standards for purification according to analytical methods of Example 1 and Comparative Example 1;

(4) FIG. 4 shows a comparison of recovery rates of internal standards for purification according to analytical methods of Example 1 and Comparative Example 2;

(5) FIG. 5 shows results of monitoring lock mass by HRGC-HRMS of Example 1;

(6) FIG. 6 shows results of monitoring lock mass by HRGC-HRMS of Comparative Example 1;

(7) FIG. 7 shows a comparison of quantitative analysis results according to analytical methods of Example 2 and Comparative Example 3; and

(8) FIG. 8 shows a comparison of recovery rates of internal standards for purification according to analytical methods of Example 2 and Comparative Example 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(9) Hereinafter, preferred examples will be provided for better understanding of the present invention. However, the following examples are provided only for understanding the present invention more easily, and the content of the present invention is not limited thereby.

Preparation Example 1: Preparation of Polymer Bead 1

(10) Polyvinyl phenylmethanol was dissolved in ethanol in a 3-neck round bottom flask under argon gas. 2,2′-azobis(2-methylpropionitrile) was added thereto, and heated to 70° C. When the temperature reached 70° C., a 2,2′-azobis(2-methylpropionitrile)-containing styrene and divinylbenzene solution was slowly added at a constant rate, and then allowed to react for 24 hours or more. As a result, Polymer Bead 1 of a polystyrene-polydivinylbenzene-polyvinylphenylmethanol terpolymer (polystyrene repeating unit:polydivinylbenzene repeating unit:polyvinylphenylmethanol repeating unit=34:34:32 (molar ratio)) was prepared.

Preparation Example 2: Preparation of Polymer Bead 2

(11) Polyvinyl phenylmethanol was dissolved in ethanol in a 3-neck round bottom flask under argon gas. 2,2′-azobis(2-methylpropionitrile) was added thereto, and heated to 70° C. When the temperature reached 70° C., a 2,2′-azobis(2-methylpropionitrile)-containing styrene and divinylbenzene solution was slowly added at a constant rate, and then allowed to react for 24 hours or more. As a result, Polymer Bead 2 of a polystyrene-polydivinylbenzene-polyvinylphenylmethanol terpolymer (polystyrene repeating unit:polydivinylbenzene repeating unit:polyvinylphenylmethanol repeating unit=35:50:15 (molar ratio)) was prepared.

Experimental Example 1: Analysis of Bead Morphology

(12) In order to examine particle morphology and particle size of Polymer Bead 1 prepared in Preparation Example 1, Polymer Bead 2 prepared in Preparation Example 2, and C.sub.18 beads (manufactured by Agilent) to be used in Comparative Example 1 described below, SEM analysis was performed, and results are shown in FIG. 2, respectively.

(13) As shown in FIG. 2, it was found that Polymer Beads 1 and 2 prepared in the preparation examples had a spherical particle shape whereas, Upti-Clean C.sub.18 beads had an irregular particle shape. It was also found that Polymer Bead 1 had an average particle size of 50 μm to 85 μm and Polymer Bead 2 had an average particle size of 34 μm to 55 μm, and Polymer Bead 2 had a more regular shape.

Example 1: Analysis of Recovery Rate of Standard for Purification Using Column Packed with Polymer Bead 2

(14) (Purification Step)

(15) A column was packed with Polymer Bead 2 prepared in Preparation Example 2, and methanol was passed through the column to remove remaining impurities in the polymer beads.

(16) Thereafter, 20 μl of a standard for purification (EDF8999) was passed through the column packed with Polymer Bead 2 to adsorb dioxin compounds onto Polymer Bead 2.

(17) Thereafter, methanol was passed through the column packed with Polymer Bead 2 onto which dioxin compounds were adsorbed, to remove components that were not adsorbed onto Polymer Bead 2.

(18) Next, toluene was introduced into the column packed with the polymer beads from which unadsorbed components were removed, to elute Polymer Bead 2-adsorbed dioxin compounds in toluene, and this solution was collected in a receiver connected to the column to obtain 3 mL of eluate. In this regard, a total time required for the purification was 10 minutes.

(19) (Concentration Step)

(20) The eluate was concentrated to 100 μl by a nitrogen concentrator and a TURBOVAP® concentrator (an instrument for solvent evaporation).

(21) (Instrumental Analysis Step)

(22) Instrumental analysis step was performed by the following method. {circle around (1)} 100 μl of the liquid concentrate was transferred into a vial and the liquid concentrate was subjected to air-drying. {circle around (2)} When 10 μl of the liquid concentrate was left in an insert, the liquid concentrate was rinsed with 0.1 mL of toluene, and subjected to air-drying in a heating block at 40° C. {circle around (3)} The procedure of {circle around (2)} was repeated three times. {circle around (4)} When about 10 μl of toluene was finally left in the insert, 10 μl of a stock solution (EDF-5999) which is an internal standard for syringe addition was added thereto. {circle around (5)} Instrumental analysis was performed by HRGC-HRMS.

Example 2: Analysis of Dioxin Compounds in Sample Using Column Packed with Polymer Bead 2

(23) (Sampling Step)

(24) An amber glass bottle with a TEFLON® (a brand name for synthetic polytetrafluoroethylene) stopper which was washed with a solvent was used to collect 2 L or more of actual wastewater from a vinyl chloride monomer (VCM) plant at a depth of 30 cm to 50 cm or to collect 2 L or more of the wastewater at 1 minute after turning on a faucet while stirring a storage tank if the faucet was connected to the sampling point.

(25) (Extraction and Concentration Steps)

(26) The collected sample was subjected to liquid-liquid extraction and Soxhlet extraction using a separatory funnel, a shaker, and a Soxhlet extractor to obtain a liquid extract. Thereafter, a predetermined amount of the liquid extract was aliquoted and 2 ng of the internal standard for purification was added thereto, and this mixture was concentrated using a TURBOVAP® (an instrument for solvent evaporation) manufactured by Zymark, Corp. to obtain 1 ml of a concentrate.

(27) After the sampling, extraction, and concentration steps, the purification step was performed in the same manner as in Example 1 to analyze dioxin compounds in the sample. In this regard, a total time required for the purification step was 20 minutes.

Comparative Example 1: Analysis of Recovery Rate of Standard for Purification Using Column Packed with C.SUB.18 .Beads

(28) A recovery rate of the standard for purification was analyzed in the same manner as in Example 1, except that a column packed with commercially available C.sub.18 beads (silica beads, manufactured by Agilent Corp.) was used in the purification step, instead of the column packed with Polymer Bead 2. In this regard, a total time required for the purification step was 10 minutes.

Comparative Example 2: Analysis of Recovery Rate of Standard for Purification Using Column Packed with Oasis HLB Beads

(29) A recovery rate of the standard for purification was analyzed in the same manner as in Example 1, except that a column packed with commercially available Oasis HLB beads (polydivinylbenzene-polyN-vinylpyrrolidone copolymer) having an average particle size of 30 μm (manufactured by Water Corp.) was used in the purification step, instead of the column packed with Polymer bead 2. In this regard, a total time required for the purification step was 10 minutes.

Comparative Example 3: Analysis of Dioxin Compounds in Sample According to Notice of Ministry of Environment

(30) In the sampling step, actual wastewater of the vinyl chloride monomer (VCM) plant was collected as a sample, and dioxin compounds in the sample were analyzed according to the test methods for dioxins and furans in wastewater samples in the Official Method of Unintentionally Produced Persistent Organic Pollutants announced by the Ministry of Environment. In this regard, a total time required for the purification step was 5 days.

Experimental Example 2: Comparison of Recovery Rates of Standards for Purification According to Kind of Beads

(31) Recovery rates in the analytical methods for dioxin compounds of Example 1, Comparative Example 1, and Comparative Example 2 were calculated by the following method. {circle around (1)} Recovery rates of .sup.37C1-2,3,7,8-TeCDD which is an internal standard for sampling and 15 kinds of internal standards for purification were calculated using .sup.13C-1,2,3,4-TeCDD and .sup.13C-1,2,3,7,8,9-HxCDD which are used as internal standards for syringe addition. {circle around (2)} A relative response factor (RRF) of the isotope substituent internal standard to .sup.13C-1,2,3,4-TeCDD and .sup.13C-1,2,3,7,8,9-HxCDD which are internal standards for syringe addition was calculated using calibration curve data according to the following Equation 1.

(32) $\begin{array}{cc}RRF=\frac{\left(A{1}_n+A{2}_n\right)}{\left(A{1}_1+A{2}_1\right)}\times \frac{\left(C_1\right)}{\left(C_n\right)}& \left[\mathrm{Equation}1\right]\end{array}$

(33) In Equation 1, A1.sub.n and A2.sub.n represent peak areas of primary and secondary selected ions for the standard for quantification, respectively, A1.sub.l and A2.sub.l represent peak areas of primary and secondary selected ions for the internal standard for syringe addition, respectively, C.sub.l represents a concentration of the internal standard for syringe addition, and C.sub.n represents a concentration of the standard for quantification. {circle around (3)} Recovery rates of 4,5 chloride and 6,7,8 chloride among the internal standards for sampling and purification were calculated by .sup.13C-1,2,3,4-TeCDD and .sup.13C-1,2,3,7,8,9-HxCDD, respectively, from the calculated RRF value and sample analysis data according to the following Equation 2.

(34) $\begin{array}{cc}\mathrm{Recovery}\mathrm{rate}\left(\%\right)=\frac{\left(A{1}_n+A{2}_n\right)}{\left(A{1}_1+A{2}_1\right)}\times \frac{1}{RRF}\times \frac{\left(C_1\right)}{\left(C_n\right)}& \left[\mathrm{Equation}2\right]\end{array}$

(35) In Equation 2, A1.sub.n and A2.sub.n represent peak areas of primary and secondary selected ions for the standard for purification, respectively, A1.sub.l and A2.sub.l represent peak areas of primary and secondary selected ions for the internal standard for syringe addition, respectively, C.sub.l represents a concentration of the internal standard for syringe addition, C.sub.n represents a concentration of the standard for quantification, and RRF represents a relative response factor.

(36) The recovery rates of the internal standards for purification in the analysis of Example 1 were calculated twice by the above method, and the recovery rates of the internal standards for purification in the analysis of Comparative Examples 1 and 2 were calculated three times by the above method, and results are shown in FIGS. 3 and 4, respectively.

(37) As shown in FIGS. 3 and 4, when the column packed with Polymer Bead 2 prepared in Preparation Example 2 was used in the purification step of Example 1, the recovery rates of the internal standards for purification were about 90% to about 130%. In contrast, when the column packed with silica beads and the column packed with Oasis HLB beads (polydivinylbenzene-polyN-vinylpyrrolidone copolymer) were used in Comparative Examples 1 and 2, respectively, there were some congeners showing the recovery rates of internal standards of less than 80%, and there was a large deviation in the recovery rate between measurements.

(38) Further, lock masses of HRGC-HRMS in the analysis of Example 1 and Comparative Example 1 were monitored and are shown in FIGS. 5 and 6. As shown in FIGS. 5 and 6, vibration of the lock mass occurred in Comparative Example 1, unlike in Example 1, indicating that purification efficiency was poor and additional purification of the analyte was required.

Experimental Example 3: Quantification Results of Dioxin Compounds in Actual Wastewater

(39) In order to examine whether quantification results of dioxin compounds in actual wastewater are valid, quantification analysis (measurement of toxicity equivalency factor) of 17 kinds of dioxin compounds (7 kinds of PCDDs and 10 kinds of PCDFs) was performed according to the analytical methods of Example 2 and Comparative Example 3, and results are shown in FIG. 7. In particular, measurement for Example 1 was performed in triplicate, and average relative response factor (RRF.sub.avg), standard deviation (SD), and relative standard deviation (RSD) of the quantitative values were calculated according to the following Equations 3 to 5, respectively.

(40) $\begin{array}{cc}{\mathrm{RRF}}_{\mathrm{avg}.}=\frac{\underset{i=1}{\overset{n}{.Math.}}{\mathrm{RRF}}_i}{n}& \left[\mathrm{Equation}3\right]\\ \mathrm{SD}=\sqrt{\frac{\underset{i=1}{\overset{n}{.Math.}}{\left({\mathrm{RRF}}_i-{\mathrm{RRF}}_{\mathrm{avg}.}\right)}^2}{n-1}}& \left[\mathrm{Equation}4\right]\\ \mathrm{RSD}=\frac{\mathrm{SD}}{{\mathrm{RRF}}_{\mathrm{avg}.}}\times 100& \left[\mathrm{Equation}5\right]\end{array}$

(41) The calculation results of Equations 3 to 5 showed that the relative standard deviation (RSD) of the quantitative values of Example 2 was 7.6%, which is in accordance with the dual measurement criteria, indicating validity of the analytical method for dioxin compounds of Example 2. Here, ‘dual measurement’ means that the operation after extraction is repeated for the same sample twice or more under the same conditions, an average value of both analytical values (total TEQ concentration of dioxin compounds) of an object at a concentration higher than a limit of quantification is obtained, and then it is confirmed whether the difference of each value with respect to the average value is 30% or less.

(42) In the same manner as in Experimental Example 2, recovery rates of the internal standards for purification of Example 2 and Comparative Example 3 were measured. In particular, measurement for Example 2 was performed in triplicate, and reliability of the analytical method was determined. The results are shown in FIG. 8.

(43) As shown in FIG. 8, when the column packed with Polymer Bead 2 prepared in Preparation Example 2 was used in the purification step of Example 2, the recovery rates of the internal standards for purification were about 86% to about 112%. In contrast, the recovery rates of the internal standards for purification in Comparative Example 3 according to the notice of the Ministry of Environment were only about 60% to about 70%. Further, most of 16 kinds of congeners which are the internal standards for purification showed high recovery rates in the analytical method of Example 2, as compared to that of Comparative Example 2.

(44) Accordingly, it can be seen that when the pretreatment method for analyzing dioxin compounds and the analytical method using the same of the present invention are employed, a time required for the purification step during pretreatment may be remarkably reduced, and recovery rates of the internal standards for purification may be improved.