METHOD FOR FRACTIONATING DIOXINS

In a standing pipe body (210), an adsorbent layer (240) filled with active magnesium silicate as an adsorbent and an alumina layer (250) positioned therebelow are arranged. A sample solution containing dioxins is applied into the pipe body (210) from the top, and an aliphatic hydrocarbon solvent is subsequently supplied into the pipe body (210) from the top. The aliphatic hydrocarbon solvent having dissolved dioxins in the sample solution passes through the adsorbent layer (240) and the alumina layer (250) in this order, and is discharged from a bottom of the pipe body (210). At this point, a dioxin group including non-ortho PCBs, PCDDs, and PCDFs is selectively trapped by the adsorbent layer (240), and mono-ortho PCBs are selectively trapped by the alumina layer (250).

TECHNICAL FIELD

The present invention relates to the method for fractionating dioxins, and specifically relates to the method for fractionating dioxins contained in an aliphatic hydrocarbon solvent solution with the dioxins. The present application claims a priority based on Japanese Application No. 2019-006673 filed in Japan on Jan. 18, 2019, and the contents of which are incorporated herein by reference.

BACKGROUND ART

With concern over environmental contamination due to dioxins as highly-toxic substances, analysis and evaluation of a contamination status due to the dioxins have been, in each country, demanded for exhaust gas from a waste incineration facility, ambient air, water such as industrial waste or river water, fly ash generated at a waste incineration facility, soil and the like. For food, similar analysis and evaluation have been demanded in many cases.

The dioxins are generally a collective term of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs). Of 209 isomer types of polychlorinated biphenyls (PCBs), the DL-PCBs are PCBs having toxicity similar to those of the PCDDs and the PCDFs, and include non-ortho PCBs and mono-ortho PCBs.

For evaluating contamination of a sample such as an environmental sample including ambient air, soil and the like or a food sample due to the dioxins, the dioxins need to be first extracted from the sample. In a case where the sample is a solid object such as soil or dry food, the dioxins are extracted from the solid object by, e.g., a Soxhlet extraction method. For example, in a case where the sample is liquid such as waste water or drinking water, the dioxins in the liquid are trapped and collected using a collector such as a filter, and thereafter, the collector is rinsed or the Soxhlet extraction method is applied to the collector to extract the dioxins collected by the collector. The dioxin obtained as described above is, quantitatively analyzed using a gas chromatograph mass spectrometry (GC/MS).

The extracts with dioxins contain various impurity components which might influence quantitative accuracy, and examples of the impurity components include polychlorinated polycyclic aromatic hydrocarbons having chemical structures or chemical behaviors similar to those of the dioxins, such as polychlorinated diphenyl ether (PCDE) and PCBs (hereinafter sometimes referred to as “non-DL-PCBs”) other than the DL-PCBs. For this reason, the extracts with the dioxins are normally purified and concentrated as necessary after purification, and finally, are applied to an analytical instrument. As an extract purification method, Patent Literature 1 describes a method using a column chromatography including a first-stage column filled with sulfuric silica gel and silver nitrate silica gel as a purifier and a second-stage column filled with activated carbon-containing silica gel or graphite carbon as an adsorbent. In this method, the activated carbon silica gel or the graphite carbon can be selectively used as the adsorbent of the second-stage column. In the case of using both of the activated carbon silica gel or the graphite carbon, each filler can be used in a stacked state or a mixed state.

In the purification method using the column chromatography, the extracts containing the dioxins are first applied into the first-stage column, and a hydrocarbon solvent is subsequently supplied to the first-stage column. The hydrocarbon solvent dissolves the dioxins in the extracts while passing through the first-stage column and the second-stage column. At this point, the dioxins dissolved in the hydrocarbon solvent pass through the purifier of the first-stage column, and adsorb to the adsorbent of the second-stage column. Generally, the impurity components contained in the extracts are dissolved in the hydrocarbon solvent together with the dioxins. Some of the impurity components are decomposed and other impurity components adsorb to the purifier while passing through the purifier of the first-stage column. Of the impurity components or decomposition products thereof, those not adsorbing to the purifier pass through the adsorbent of the second-stage column in a state in which these components are dissolved in the hydrocarbon solvent, and are discharged from the column.

Next, the first-stage column and the second-stage column are separated from each other, and alkyl benzene capable of dissolving the dioxins is supplied to the second-stage column. Then, the dioxins adsorbed on the second-stage column, from which the impurity components have been separated, are desorbed by eluting the dioxins by an alkyl benzene solution. Such dioxins eluted by an alkyl benzene solution, after having been concentrated as necessary, are analyzed by the GC/MS.

In such a purification method, all types of dioxins contained in the extracts are trapped by the adsorbent of the second-stage column, and these dioxins are eluted by using the alkyl benzene. Thus, in the GC/MS measurement, all types of dioxins contained in the alkyl benzene solution can be simultaneously analyzed.

However, when the alkyl benzene solution containing all types of dioxins is analyzed simultaneously by GC/MS, quantitative accuracy of an analysis might lack reliability due to mutual interference between several PCDDs isomers and some of PCBs. For example, in the case of analyzing all type of dioxins by a high-resolution GC/MS, it has been known that the mono-ortho PCBs influence a result of quantitative analysis of the PCDDs and the PCDFs, and conversely, the PCDDs and the PCDFs influence a result of quantitative analysis of the mono-ortho PCBs.

For this reason, in general, the dioxins have been fractionated into several compound groups by some adsorbents. For example, Patent Literature 2 describes a method in which graphite-like carbon or a mixture of graphite-like carbon and other materials such as silica gel, activated carbon-containing silica gel, activated carbon, alumina, and zeolite is used as an adsorbent for the dioxins.

In this method, a purified dioxin solution is supplied to a column filled with the adsorbent such that the dioxins adsorb to the adsorbent. Then, several types of solvents are sequentially supplied to the column, thereby preparing several types of dioxin solutions. Patent Literature 2 describes that by such a method, three types of dioxin solutions including a solution containing the PCBs other than the DL-PCBs, a solution containing the mono-ortho PCBs, and a solution containing the non-ortho PCBs, the PCDDs, and the PCDFs can be prepared, for example.

However, in this method, all types of dioxins adsorb to the adsorbent as in the method described in Patent Literature 1, and therefore, it is difficult to precisely fractionate the dioxins. For example, there is a probability that the fraction containing non-ortho PCBs, PCDDs and PCDFs is contaminated with some of the mono-ortho PCBs, and there is also the opposite situation as well.

PRIOR ART LITERATURE

Patent Literature

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

The present invention is intended to fractionate, with a high accuracy, dioxins into a dioxin group including non-ortho PCBs, PCDDs, and PCDFs and mono-ortho PCBs.

Solutions to the Problems

The present invention relates to the method for fractionating dioxins, and the fractionating method includes the step of causing an aliphatic hydrocarbon solvent solution with the dioxins to pass through an adsorbent layer using an adsorbent mixed active magnesium silicate.

In such a fractionating method, when the aliphatic hydrocarbon solvent solution with the dioxins passes through the adsorbent layer, a dioxin group including non-ortho PCBs, PCDDs, and PCDFs adsorbs, among the dioxins, to the adsorbent containing the active magnesium silicate. On the other hand, mono-ortho PCBs of the dioxins remain in the aliphatic hydrocarbon solvent solution, and passes through the adsorbent layer. As a result, the dioxins in the aliphatic hydrocarbon solvent solution are fractionated into the dioxin group, which is trapped by the adsorbent layer, including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs remaining in the aliphatic hydrocarbon solvent solution.

One aspect of the adsorbent used in the fractionating method further contains graphite mixed with the active magnesium silicate. The content of the graphite in the adsorbent of this aspect is preferably equal to or lower than 25% by weight. Moreover, the active magnesium silicate in the adsorbent of this aspect is, for example, prepared in such a manner that a mixture of magnesium silicate and graphite is heated to equal to or lower than 650° C.

In one aspect of the fractionating method of the present invention, the aliphatic hydrocarbon solvent solution having passed through the adsorbent layer further passes through an alumina layer.

In the fractionating method of this aspect, when the aliphatic hydrocarbon solvent solution having passed through the adsorbent layer passes through the alumina layer, the remaining mono-ortho PCBs adsorb to the alumina layer. As a result, the dioxins in the aliphatic hydrocarbon solvent solution are fractionated into the dioxin group, which is selectively trapped in the adsorbent layer, including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs selectively trapped in the alumina layer.

The fractionating method of this aspect may further include the step of supplying a solvent capable of dissolving the dioxins to the adsorbent layer through which the aliphatic hydrocarbon solvent solution has passed to collect the solvent having passed through the adsorbent layer and the step of supplying a solvent capable of dissolving the dioxins to the alumina layer through which the aliphatic hydrocarbon solvent solution has passed to collect the solvent having passed through the alumina layer.

In a case where the fractionating method of this aspect further includes these steps, the dioxin group, which is trapped by the adsorbent layer, including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs trapped by the alumina layer are dissolved in the solvents supplied to each layer to dissolve the dioxins, and are extracted from each layer. Then, these dioxins are obtained as separate extracts.

The present invention according to another aspect relates to a tool for fractionating dioxins contained in a dioxin solution. The fractionating tool includes a pipe body opening at both ends and an adsorbent layer filled into the pipe body and using an adsorbent mixed active magnesium silicate.

When the dioxins contained in the dioxin solution are fractionated using such a fractionating tool, the dioxin solution is added to the adsorbent layer of the pipe body. Then, when an aliphatic hydrocarbon solvent capable of dissolving the dioxins is supplied to the adsorbent layer to which the dioxin solution has been added, the aliphatic hydrocarbon solvent dissolves the dioxins and turns into an aliphatic hydrocarbon solvent with the dioxins, and then, passes through the adsorbent layer. At this point, the dioxins are dissolved in the adsorbent layer, and among these dioxins, a dioxin group including non-ortho PCBs, PCDDs, and PCDFs adsorbs to the adsorbent. The aliphatic hydrocarbon solvent passes through the adsorbent layer in a state in which mono-ortho PCBs are dissolved in the aliphatic hydrocarbon solvent. As a result, the dioxins contained in the dioxin solution are fractionated into the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs.

In one aspect of the fractionating tool, the adsorbent further contains graphite mixed with the active magnesium silicate. In this case, the content of the graphite in the adsorbent is preferably equal to or lower than 25% by weight.

One aspect of the fractionating tool of the present invention further includes an alumina layer filled into the pipe body. One example of the pipe body in the fractionating tool of this aspect has an opening between the adsorbent layer and the alumina layer.

In the fractionating tool of this aspect, the mono-ortho PCBs contained in the aliphatic hydrocarbon solvent having passed through the adsorbent layer adsorb to the alumina layer, and are separated from the aliphatic hydrocarbon solvent. As a result, the dioxins in the dioxin solution are fractionated into the dioxin group, which is selectively trapped by the adsorbent layer, including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs selectively trapped by the alumina layer.

The present invention according to still another aspect relates to the method for preparing a sample for analyzing dioxins contained in a dioxin solution. Such a preparation method includes the step of adding the dioxin solution to a purification layer including a silver nitrate silica gel layer and a sulfuric silica gel layer, the step of supplying an aliphatic hydrocarbon solvent to the purification layer to which the dioxin solution has been added, the step of causing the aliphatic hydrocarbon solvent having passed through the purification layer to pass through an adsorbent layer using an adsorbent mixed active magnesium silicate, the step of causing the aliphatic hydrocarbon solvent having passed through the adsorbent layer to pass through an alumina layer, the step of supplying a solvent capable of dissolving the dioxins to the alumina layer through which the aliphatic hydrocarbon solvent has passed to collect, as a first analysis sample, the solvent having passed through the alumina layer, and the step of supplying a solvent capable of dissolving the dioxins to the adsorbent layer through which the aliphatic hydrocarbon solvent has passed to collect, as a second analysis sample, the solvent having passed through the adsorbent layer.

In such a preparation method, when the aliphatic hydrocarbon solvent is supplied to the purification layer to which the dioxin solution has been added, the aliphatic hydrocarbon solvent passes through the purification layer. At this point, the dioxins and impurity components contained in the dioxin solution are dissolved in the aliphatic hydrocarbon solvent. Then, some of the impurity components react with the silver nitrate silica gel layer or the sulfuric silica gel layer of the purification layer, and are decomposed. Moreover, some of the impurity components and decomposition products adsorb to the silver nitrate silica gel layer or the sulfuric silica gel layer. Meanwhile, the dioxins pass through the purification layer in a state in which the dioxins are dissolved in the aliphatic hydrocarbon solvent. As a result, the dioxins are separated from some of the impurity components.

When the aliphatic hydrocarbon solvent having passed through the purification layer and having dissolved the dioxins passes through the adsorbent layer, a dioxin group including non-ortho PCBs, PCDDs, and PCDFs selectively adsorb, among the dioxins, to the adsorbent. When passing through the alumina layer, mono-ortho PCBs of the dioxins selectively adsorb to the alumina layer. Thus, the first analysis sample is an analysis sample for the mono-ortho PCBs, and the second analysis sample is an analysis sample for the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs. That is, according to the preparation method, the analysis sample for the mono-ortho PCBs and the analysis sample for the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs can be separately prepared.

The present invention according to still another aspect relates to the method for determining dioxins contained in a dioxin solution. Such a determination method includes the step of separately analyzing, by a gas chromatography method or a bioassay method, the first analysis sample and the second analysis sample prepared by the method for preparing the analysis sample for the dioxins according to the present invention.

In such a determination method, mono-ortho PCBs can be analyzed by analysis of the first analysis sample, and non-ortho PCBs, PCDDs, and PCDFs can be analyzed by analysis of the second analysis sample.

Effects of the Invention

The method for fractionating the dioxins according to the present invention uses the adsorbent layer using the adsorbent containing the active magnesium silicate. Thus, the dioxins can be fractionated into the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs, and the accuracy of such fractionation can be enhanced.

The dioxin fractionating tool according to the present invention includes the adsorbent layer using the adsorbent containing the active magnesium silicate. Thus, the dioxins can be fractionated into the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs, and the accuracy of such fractionation can be enhanced.

The method for preparing the analysis sample for the dioxins according to the present invention uses the adsorbent layer using the adsorbent containing the active magnesium silicate. Thus, the analysis sample for the mono-ortho PCBs and the analysis sample for the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs can be separately prepared from the dioxin solution.

The method for determining the dioxins according to the present invention includes the step of separately analyzing the first analysis sample and the second analysis sample prepared by the method for preparing the analysis sample for the dioxins according to the present invention. Thus, the mono-ortho PCBs can be analyzed by analysis of the first analysis sample, and the non-ortho PCBs, the PCDDs, and the PCDFs can be analyzed by analysis of the second analysis sample.

DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of an analysis sample preparation method according to the present invention will be described below with reference to the figures. Each figure illustrates the outline of an example of an apparatus used for performing the preparation method of the present invention or a fractionating tool, and the structure, shape, size and the like of each unit are not precisely reflected on each figure.

First Embodiment

A first embodiment of an apparatus capable of performing the analysis sample preparation method according to the present invention will be described with reference toFIG. 1. InFIG. 1, a preparation apparatus100is for preparing a dioxin analysis sample from a dioxin solution, and mainly includes a dioxin fractionating tool200, a heating apparatus300, a solvent supply apparatus400, a solvent outflow path500, a first extraction path600, and a second extraction path700.

The fractionating tool200includes a pipe body210. The pipe body210is made of a material having at least solvent resistance, chemical resistance, and thermal resistance, such as glass, resin, or metal having these properties. The pipe body210is formed in a continuous cylindrical shape opening at both ends, the pipe body210having an opening211at one end and having an opening212at the other end. The pipe body210has a large-diameter portion213formed on an opening211side and set to have a relatively-large diameter and a small-diameter portion214formed on an opening212side and set to have a relatively-small diameter. The small-diameter portion214has two branched paths as openings, i.e., a first branched path215and a second branched path216provided with a clearance.

The pipe body210is held in a standing state, and is filled with a purification layer220and a fractionating layer230.

The large-diameter portion213is filled with the purification layer220, and the purification layer220is a multilayer silica gel layer in which a silver nitrate silica gel layer221, a first active silica gel layer223, a sulfuric silica gel layer222, and a second active silica gel layer224are arranged in this order from the opening211side.

The silver nitrate silica gel layer221is made of silver nitrate silica gel, and is provided for decomposing or adsorbing some of impurity components mixed with the dioxin solution. The silver nitrate silica gel used herein is prepared in such a manner that after a silver nitrate solution has been uniformly added to a surface of silica gel (normally active silica gel of which degree of activity has been enhanced by heating) in the form of grain with a particle size of about 40 to 210 μm, moisture is removed by heating under a reduced pressure. The amount of the silver nitrate solution added to the silica gel is normally preferably set to 5 to 20% of the weight of the silica gel.

The density of the filled silver nitrate silica gel in the silver nitrate silica gel layer221is not specifically limited, but is normally preferably set to 0.3 to 0.8 g/cm3 and more preferably 0.4 to 0.7 g/cm3.

The sulfuric silica gel layer222is made of sulfuric silica gel, and is provided for decomposing or adsorbing some of the impurity components mixed with the dioxin solution other than dioxins. The sulfuric silica gel used herein is prepared in such a manner that concentrated sulfuric acid is uniformly added to a surface of silica gel (normally active silica gel of which degree of activity has been enhanced by heating) in the form of grain with a particle size of about 40 to 210 μm. The amount of the concentrated sulfuric acid added to the silica gel is normally preferably set to 10 to 130% of the weight of the silica gel.

The density of the filled sulfuric silica gel in the sulfuric silica gel layer222is not specifically limited, but is normally preferably set to 0.3 to 1.1 g/cm3 and more preferably 0.5 to 1.0 g/cm3.

The first active silica gel layer223is arranged to avoid chemical reaction between the silver nitrate silica gel layer221and the sulfuric silica gel layer222due to direct contact therebetween, and is made of silica gel in the form of grain with a particle size of about 40 to 210 μm. The silica gel used herein may be one of which degree of activity has been enhanced as necessary by heating.

The second active silica gel layer224is made of silica gel similar to that of the first active silica gel layer223, and is provided for adsorbing some of the impurity components decomposed due to reaction with the sulfuric silica gel layer222, a decomposition product, and sulfuric silica eluted from the sulfuric silica gel layer222to prevent these components from moving to the fractionating layer230.

In the purification layer220, a ratio between the silver nitrate silica gel layer221and the sulfuric silica gel layer222is set such that the weight ratio of the sulfuric silica gel layer222to the silver nitrate silica gel layer221is preferably set to 1.0 to 50 and more preferably 3.0 to 30. When the weight ratio of the sulfuric silica gel layer222exceeds 50, the percentage of the silver nitrate silica gel layer221is relatively low, and for this reason, there is a probability that the capacity of the purification layer220for adsorbing the impurity components contained in the dioxin solution is insufficient. Conversely, the weight ratio of the sulfuric silica gel layer222is lower than 1.0, there is a probability that the capacity of the purification layer220for decomposing the impurity components contained in the dioxin solution is insufficient.

The fractionating layer230is provided for fractionating the dioxins contained in the dioxin solution, and includes an adsorbent layer240using an adsorbent mixed active magnesium silicate and an alumina layer250. The small-diameter portion214is filled with the adsorbent layer240and the alumina layer250such that the adsorbent layer240and the alumina layer250are provided with a clearance. More specifically, the small-diameter portion214is, between the first branched path215and the second branched path216, filled with the adsorbent layer240. The small-diameter portion214is, between the second branched path216and the opening212, filled with the alumina layer250.

The active magnesium silicate contained in the adsorbent used in the adsorbent layer240is for removing moisture by heating of magnesium silicate and enhancing an adsorption capacity accordingly. The magnesium silicate described herein is silicate salt that an electronegative atomic group containing oxygen and magnesium around a silicon atom is coordinated, and generally represented by a chemical formula xMgO.ySiO2. The magnesium silicate includes various compositions with different combinations of x and y, and may be hydrate (in this case, represented by a chemical formula xMgO.ySiO2.nH2O). As representative examples of the combination (x:y) of x and y in sodium silicate, 2:5, 2:3, and 3:4 have been known. Of these combinations, one that x:y is 2:3 is preferably used.

As the active magnesium silicate, one obtained in such a manner that porous magnesium silicate capable of ensuring liquid permeability in the adsorbent layer240and provided in the form of grain or powder, such as magnesium silicate with a particle size of 38 to 250 μm (60 to 390 mesh) or specifically magnesium silicate with a particle size of 75 to 150 μm (100 to 200 mesh), is heated and activated is preferred. The magnesium silicate in the form of grain or powder is, for example, commercially available by multiple companies under the name of “Florisil,” and these commercially-available products can be used.

Heating treatment for activating the magnesium silicate is, for example, preferably executed at 650° C. or lower under the flow of inert gas such as nitride by means of a tubular furnace, and is specifically preferably executed at 500° C. or lower. At this point, the flow rate of the inert gas is preferably set to 0.5 to 1.0 L/minute. Moreover, heating time is preferably set to 0.5 to 3 hours, and is specifically preferably set to 1 to 2 hours. The magnesium silicate heated under a temperature condition exceeding 650° C. is altered beyond the range of activation by moisture removal, and for this reason, fractionation into a dioxin group including non-ortho PCBs, PCDDs, and PCDFs and mono-ortho PCBs becomes difficult.

The adsorbent used in the adsorbent layer240may further contain graphite mixed with the active magnesium silicate. In the case of using such an adsorbent, the dioxin analysis sample fractionated into an analysis sample for the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs and an analysis sample for the mono-ortho PCBs with a higher accuracy can be prepared from the dioxin solution.

As the graphite, various commercially-available products can be used. Normally, one provided in the form of grain or powder with a particle size of about 40 to 200 μm and formed such that the specific surface area thereof measured by a BET method is 10 to 500 m2/g, specifically 50 to 200 m2/g, is preferred. Moreover, as the graphite, one heated or rinsed with an organic solvent for removing an organic compound remaining as an impure component is preferred.

The percentage of the graphite in the adsorbent is preferably equal to or lower than 25% by weight, more preferably equal to or lower than 20% by weight, much more preferably equal to or lower than 15% by weight, and specifically preferably equal to or lower than 12.5% by weight. In a case where the percentage of the graphite exceeds 25% by weight, there is a probability that the capacity of the adsorbent layer240for adsorbing the mono-ortho PCBs is enhanced and the capacity of the adsorbent layer240for fractionation into the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs is degraded.

The mixture of the active magnesium silicate and the graphite in the adsorbent may be one obtained in such a manner that a mixture of the magnesium silicate and the graphite is heated to activate the magnesium silicate in such a mixture. In a case where the dioxin solution contains an impurity component derived from an environmental component, specifically a case where an aromatic hydrocarbon compound derived from the environmental component is contained as the impurity component, tendency shows that the capacity for fractionation into the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs is degraded due to influence of the impurity component. However, the above-described mixture is used in the absorbent so that the fractionation capacity can be enhanced.

The treatment for heating the mixture of the magnesium silicate and the graphite is, for example, preferably executed at 650° C. or lower under the flow of inert gas such as nitrogen by means of a tubular furnace, and is specifically preferably executed at 500° C. or lower. At this point, the flow rate of the inert gas is preferably set to 0.5 to 1.0 L/minute. Moreover, heating time is preferably set to 0.5 to 3 hours, and is specifically preferably set to 1 to 2 hours. In a case where a temperature condition for the heating treatment exceeds 650° C., the magnesium silicate is altered beyond the range of activation by moisture removal, and fractionation into the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs becomes difficult.

The density of the filled adsorbent in the adsorbent layer240is not specifically limited, but is normally preferably set to 0.2 to 0.6 g/cm3 and more preferably 0.3 to 0.5 g/cm3.

The alumina layer250is filled with alumina in the form of grain. The alumina used herein may be any of basic alumina, neutral alumina, and acidic alumina. The degree of activity of the alumina is not specifically limited. The preferred particle size of the alumina is normally 40 to 300 μm.

The density of the filled alumina in the alumina layer250is not specifically limited, but is normally preferably set to 0.5 to 1.2 g/cm3 and more preferably 0.8 to 1.1 g/cm3.

An amount ratio (A:B) between the adsorbent layer240(A) and the alumina layer250(B) is normally preferably set to 1:0.5 to 1:3 in terms of volume ratio and more preferably 1:1 to 1:2, considering enhancement of fractionation accuracy and reduction in the probability of some of the dioxins leaking without being trapped by the fractionating layer230.

The size of the fractionating tool200can be set as necessary according to the amount of dioxin solution treated by the preparation apparatus100, and is not specifically limited. For example, in a case where the dioxin solution amount is about 1 to 20 mL, the large-diameter portion213is preferably configured such that a portion fillable with the purification layer220has an inner diameter of 10 to 20 mm and a length of about 100 to 300 mm. Moreover, the small-diameter portion214preferably has an inner diameter of 3 to 10 mm, and is preferably configured such that the length of a portion fillable with the adsorbent layer240is about 20 to 80 mm and the length of a portion fillable with the alumina layer250is about 20 to 80 mm.

The heating apparatus300is arranged to surround the outer periphery of the large-diameter portion213, and is provided for heating the silver nitrate silica gel layer221and the first active silica gel layer223of the purification layer220and part of the sulfuric silica gel layer222, i.e., a portion in the vicinity of the silver nitrate silica gel layer221.

The solvent supply apparatus400has a first solvent supply path420extending from a first solvent container410to the pipe body210. The first solvent supply path420is detachable from the opening211of the pipe body210, and when attached to the opening211, can air-tightly close the opening211. The first solvent supply path420has, in this order from a first solvent container410side, an air introduction valve423and a first pump421and a first valve422for supplying a solvent stored in the first solvent container410to the pipe body210. The air introduction valve423is a three-way valve having an air introduction path424opening at one end, and is provided for switching a flow path to an air introduction path424side or the first solvent container410side. The first valve422is a two-way valve, and is provided for switching the first solvent supply path420between an open state and a closed state.

The solvent stored in the first solvent container410is an aliphatic hydrocarbon solvent capable of dissolving the dioxins and preferably a saturated aliphatic hydrocarbon solvent with a carbon number of 5 to 8. Examples of the solvent include n-pentane, n-hexane, n-heptane, n-octane, iso-octane, and cyclohexane. These solvents may be used as a mixture, as necessary.

The solvent outflow path500has a flow path510air-tightly connected to the opening212of the pipe body210. The flow path510has a second valve520. The second valve520is a three-way valve, and a discarding path531for discarding a solvent from the pipe body210and a second solvent supply path541for supplying a solvent to the pipe body210communicate with the flow path510. The flow path510is provided for switching such communication to communication to either one of the discarding path531or the second solvent supply path541.

The second solvent supply path541has a second pump542, and communicates with a second solvent container543configured to store a solvent for extracting the dioxins trapped by the fractionating tool200. The extraction solvent stored in the second solvent container543can be selected according to a later-described dioxin determination method. In a case where a gas chromatography method is employed as the determination method, a solvent suitable for such a method, such as toluene or benzene, can be used. Alternatively, a solvent mixture obtained in such a manner that an aliphatic hydrocarbon solvent or an organic chlorine-based solvent is added to the toluene or the benzene can be used. In the case of using the solvent mixture, the percentage of the toluene or the benzene is set to equal to or higher than 50% by weight. Examples of the aliphatic hydrocarbon solvent used in the solvent mixture include n-pentane, n-hexane, n-heptane, n-octane, iso-octane, and cyclohexane. Examples of the organic chlorine-based solvent include dichloromethane, trichloromethane, and tetrachloromethane. Of these extraction solvents, the toluene is specifically preferred because the dioxins can be extracted from the fractionating tool200by use of a small amount of the solvent.

In a case where a bioassay method is employed as the determination method, a solvent suitable for such a method, such as hydrophilic solvents including dimethylsulfoxide (DMSO) and methanol, is used.

The first extraction path600has a first recovery path610extending from the first branched path215. The first recovery path610air-tightly communicates the first branched path215at one end, and at the other end, is air-tightly inserted into a first recovery container620for recovering a solvent. One end of a first ventilation path630is, independently of the first recovery path610, air-tightly inserted into the first recovery container620. The first ventilation path630includes, at the other end, a third valve631. The third valve631is a three-way valve, and communicates with an open path632opening at one end and an air supply path634including a compressor633for sending compressed air to the first ventilation path630. The third valve631is provided for switching the first ventilation path630to communicate with either one of the open path632or the air supply path634.

The second extraction path700has a second recovery path710extending from the second branched path216. The second recovery path710air-tightly communicates with the second branched path216at one end, and at the other end, is air-tightly inserted into a second recovery container720for recovering a solvent. One end of a second ventilation path730is, independently of the second recovery path710, air-tightly inserted into the second recovery container720. The second ventilation path730includes a fourth valve731. The fourth valve731is a two-way valve, and is provided for switching the second ventilation path730between an open state and a closed state.

Next, the method for preparing the dioxin analysis sample from the dioxin solution by means of the above-described preparation apparatus100will be described. First, in the preparation apparatus100, the first valve422, the air introduction valve423, the second valve520, the third valve631, and the fourth valve731are set to prescribed initial states. That is, the first valve422is set to an open state, and the air introduction valve423is set to communicate with the first solvent container410side. Moreover, the second valve520is set such that the flow path510communicates with the discarding path531. Further, the third valve631is set such that the first ventilation path630and the air supply path634communicate with each other, and the fourth valve731is set to a closed state.

The analysis sample preparation method mainly includes dioxin fractionating and extraction steps.

After setting to the initial states, the dioxin solution is applied into the fractionating tool200. At this point, the first solvent supply path420is detached from the pipe body210, and the dioxin solution is applied into the purification layer220through the opening211. Then, after the pipe body210has been attached to the first solvent supply path420, the heating apparatus300is actuated to heat part of the purification layer220, i.e., the entirety of the silver nitrate silica gel layer221and the first active silica gel layer223and part of the sulfuric silica gel layer222.

The dioxin solution applied herein is, for example, an extract obtained in such a manner that dioxins are, using a solvent, extracted from a sample which might contain the dioxins, such as an environmental sample including ambient air and soil or a food sample. However, the dioxin solution may be oil-like food which might contain dioxins, such as fish oil.

Such a dioxin solution often contains, as the impurity components, polychlorinated polycyclic aromatic hydrocarbons such as PCDE and non-DL-PCBs and other aromatic hydrocarbon compounds which have chemical structures or chemical behaviors similar to those of the dioxins and have the possibility of influencing a dioxin quantitative accuracy. Specifically, an extract with dioxins from an environmental sample such as soil, exhaust gas from a combustion furnace or the like, a bottom material, or sludge often contains, as the impurity components, various organic compounds which are less likely to be separated from the dioxins, and typically contains an aromatic hydrocarbon compound. These impurity compounds are highly likely to influence the accuracy of fractionating the dioxins into the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs. In the case of the extracts with dioxins from the soil, such extracts often contain, as the impurity components, paraffins (straight-chain hydrocarbon compounds) contained much in the soil. The paraffins are likely to adsorb to a carbon-based adsorbent together with the PCDDs, the PCDFs, and the non-ortho PCBs, and are likely to be extracted from the adsorbent together with the PCDDs, the PCDFs, and the non-ortho PCBs. For this reason, the paraffins are known as a substance responsible for lock mass fluctuation influencing the analysis accuracy in the case of analyzing the dioxins by a GC/MS method (specifically a GC-HRMS method).

The extracts with dioxins can be directly applied into the fractionating tool200as long as the aliphatic hydrocarbon solvent is used for such a solution. In a case where the extract is obtained by extraction using an organic solvent other than the aliphatic hydrocarbon solvent, such as the aromatic hydrocarbon solvent including the toluene, such an extract can be applied into the fractionating tool200after the aromatic hydrocarbon solvent used for extraction has been substituted for the aliphatic hydrocarbon solvent. The aliphatic hydrocarbon solvent used for extraction or solvent substitution is normally preferably an aliphatic hydrocarbon solvent with a carbon number of 5 to 10. Examples of the aliphatic hydrocarbon solvent include n-hexane, iso-octane, nonane, and decane. Specifically, inexpensive n-hexane is preferred.

The amount of dioxin solution applied into the fractionating tool200is normally preferably about 1 to 10 mL. The solution to be applied can be concentrated in such a manner that part of the solvent is distilled.

In a case where the dioxin solution is in the form of oil such as fish oil, such a dioxin solution can be applied into the fractionating tool200together with the aliphatic hydrocarbon solvent which can dissolve the dioxin solution, or can be applied into the fractionating tool200as a solution in which the solvent has been dissolved in advance. In this case, the total amount of dioxin solution and aliphatic hydrocarbon solvent is set to the above-described injection amount.

The applied dioxin solution penetrates an upper portion of the silver nitrate silica gel layer221, and is heated by the heating apparatus300together with part of the purification layer220. The temperature of heating by the heating apparatus300is equal to or higher than 35° C., preferably equal to or higher than 50° C., and more preferably equal to or higher than 60° C. By such heating, some of the impurity components in the solution other than the dioxins react with the purification layer220, and are decomposed. In a case where the heating temperature is lower than 35° C., reaction among the impurity components and the purification layer220is less likely to progress, and there is a probability that some of the impurity components easily remain in the dioxin analysis sample. The upper limit of the heating temperature is not specifically limited, but is normally preferably equal to or lower than a boiling temperature in terms of safety.

Upon heating, the silver nitrate silica gel layer221and the sulfuric silica gel layer222are stacked with the first active silica gel layer223being interposed therebetween, and therefore, reaction therebetween is reduced.

Next, the solvent is supplied from the solvent supply apparatus400to the fractionating tool200after a lapse of 10 to 60 minutes from the start of heating. At this point, the heating apparatus300may be kept actuated, or may be stopped. At this step, the first pump421is actuated with the first valve422being maintained in the open state, thereby supplying a moderate amount of solvent stored in the first solvent container410into the pipe body210through the opening211by way of the first solvent supply path420. This solvent dissolves the dioxins, impurity component decomposition products, and remaining undecomposed impurity components (these impurity components normally include the non-DL-PCBs) in the dioxin solution, and as the aliphatic hydrocarbon solvent solution containing the dioxins, passes through the purification layer220. At this point, the decomposition products and some of the impurity components adsorb to the silver nitrate silica gel layer221, the first active silica gel layer223, the sulfuric silica gel layer222, and the second active silica gel layer224. Moreover, the solvent passing through the purification layer220is naturally cooled by an unheated portion of the heating apparatus300, i.e., a lower portion of the sulfuric silica gel layer222and the second active silica gel layer224.

The solvent having passed through the purification layer220flows toward the fractionating layer230, and passes through the adsorbent layer240and the alumina layer250. The solvent flows into the flow path510through the opening212, and is discarded through the discarding path531. At this point, the dioxins contained in the solvent from the purification layer220are trapped by the fractionating layer230, and are separated from the solvent. More specifically, in the fractionating layer230, the non-ortho PCBs, the PCDDs, and the PCDFs of the dioxins adsorb to the adsorbent layer240, and the mono-ortho PCBs adsorb to the alumina layer250. Thus, the dioxins contained in the solvent is, in the fractionating layer230, fractionated into the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs.

Some of the impurity components contained in the solvent having passed through the purification layer220pass through the fractionating layer230and are discarded together with the solvent. Some other impurity components are trapped by the fractionating layer230. For example, the non-DL-PCBs and the PCDE adsorb, together with the mono-ortho PCBs, to the alumina layer250. Moreover, the aromatic organic compounds and the paraffins pass through the fractionating layer230, and are discarded through the discarding path531.

Next, the dioxins having adsorbed to the fractionating layer230are extracted using the solvent, and the dioxin analysis sample is prepared. Before such preparation, the purification layer220and the fractionating layer230are dried in the preparation apparatus100. At this point, the air introduction valve423of the solvent supply apparatus400is first switched to the air introduction path424side. Then, the first pump421is actuated to suck air from the air introduction path424.

The air sucked from the air introduction path424is supplied into the pipe body210through the opening211by way of the first solvent supply path420. The air passes through the purification layer220and the fractionating layer230to flow into the flow path510through the opening212, and is discharged through the discarding path531. At this point, the solvent remaining in the purification layer220is pushed out by the passing air, and moves to the fractionating layer230. As a result, the purification layer220is dried.

Next, the first pump421is stopped, and the first valve422is switched to a closed state. Then, the compressor633is actuated on the first extraction path600.

By actuation of the compressor633, compressed air is supplied into the first branched path215from the air supply path634through the first ventilation path630, the first recovery container620, and the first recovery path610. Such compressed air passes through the fractionating layer230, and flows into the flow path510through the opening212. The compressed air is discharged through the discarding path531. At this point, the solvent having moved from the purification layer220to the fractionating layer230and the solvent remaining in each layer of the fractionating layer230are pushed out by the compressed air, and are discharged through the discarding path531together with the compressed air. As a result, each layer of the fractionating layer230is dried.

At a first step for preparing the dioxin analysis sample, the compressor633is stopped, and the fourth valve731of the second extraction path700is switched to an open state. On the solvent outflow path500, the second valve520is switched such that the flow path510communicates with the second solvent supply path541, and the second pump542is actuated. Accordingly, a moderate amount of solvent stored in the second solvent container543is supplied into the pipe body210through the second solvent supply path541and the flow path510through the opening212.

The solvent supplied into the pipe body210through the flow path510flows into the second branched path216through the alumina layer250, and is recovered by the second recovery container720through the second recovery path710of the second extraction path700. At this point, the solvent dissolves the mono-ortho PCBs and the non-DL-PCBs having adsorbed to the alumina layer250, and is recovered by the second recovery container720as a solution from each these PCBs have been extracted, i.e., a first analysis sample.

At this step, the alumina layer250can be heated from the outside of the pipe body210. In the case of heating the alumina layer250, the mono-ortho PCBs and the non-DL-PCBs can be efficiently extracted from the alumina layer250with a reduced usage of the extraction solvent. The temperature of heating the alumina layer250is normally preferably controlled to about 50° C. to lower than the boiling temperature of the extraction solvent and specifically equal to or lower than 95° C.

At a subsequent step for preparing the analysis sample, after the second pump542has been temporarily stopped, the third valve631is switched such that the first ventilation path630and the open path632communicate with each other on the first extraction path600, and the fourth valve731of the second extraction path700is switched to the closed state. Then, on the solvent outflow path500, the second pump542is actuated again in a state in which the second valve520is maintained such that the flow path510communicates with the second solvent supply path541. Accordingly, a moderate amount of solvent stored in the second solvent container543is supplied into the pipe body210through the opening212by way of the second solvent supply path541and the flow path510.

The solvent supplied into the pipe body210from the flow path510passes through the alumina layer250and the adsorbent layer240in this order, and flows into the first branched path215. The solvent is recovered by the first recovery container620through the first recovery path610of the first extraction path600. At this point, the solvent dissolves the dioxin group, which includes the non-ortho PCBs, the PCDDs, and the PCDFs, having adsorbed to the adsorbent layer240, and is recovered by the first recovery container620as a solution from which the dioxin group has been extracted, i.e., a second analysis sample.

At this step, the adsorbent layer240can be heated from the outside of the pipe body210. In the case of heating the adsorbent layer240, the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs can be efficiently extracted from the adsorbent layer240with a reduced usage of the extraction solvent. The temperature of heating the adsorbent layer240is normally preferably controlled to about 50° C. to lower than the boiling temperature of the extraction solvent and specifically equal to or higher than 80° C. and equal to or lower than 95° C.

By the above-described extraction step, the analysis sample for the mono-ortho PCBs and the analysis sample for the non-ortho PCBs, the PCDDs, and the PCDFs are separately obtained.

These two types of analysis samples prepared as described above are separately applied to dioxin analysis. According to the type of solvent used for extracting the dioxins from the fractionating layer230, a GC/MS method such as GC-HRMS, GC-MSMS, GC-QMS, or ion trap GC/MS, a gas chromatography method such as GC/ECD, or a bioassay method can be normally employed as the determination method.

In analysis of the analysis sample (the first analysis sample) for the mono-ortho PCBs, such an analysis sample substantially contains no dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs, and therefore, the mono-ortho PCBs can be quantified with a high accuracy without receiving influence of the dioxin group. Moreover, such an analysis sample contains the non-DL-PCBs together with the mono-ortho PCBs, and therefore, the non-DL-PCBs contained in the dioxin solution can be also quantified with a high accuracy. For example, according to food regulation standards (COMMISSION REGULATION (EU) No 1259/2011) in the European Union (EU), the dioxins and prescribed non-DL-PCBs (six types of PCBs of which IUPAC numbers are #28, #52, #101, #138, #153, and #180 and of which chlorine numbers are 3 to 7) are set as targets for analysis of harmful substances contained in food such as meats including beef and pork and eggs, but these PCBs can be quantified by analysis of this analysis sample.

On the other hand, in analysis of the analysis sample (the second analysis sample) for the non-ortho PCBs, the PCDDs, and the PCDFs, such an analysis sample substantially contain no mono-ortho PCBs and no non-DL-PCBs, and therefore, the non-ortho PCBs, the PCDDs, and the PCDFs can be quantified with a high accuracy without receiving influence of these PCBs.

Note that GC-MSMS or GC-TOFMS can be used as the GC/MS method, and in this case, two types of analysis samples can be used as a mixture for analysis at the same time.

In the preparation apparatus100, the second extraction path700can be changed as illustrated inFIG. 2. The changed second extraction path700has a solvent path740extending from the second branched path216. The solvent path740air-tightly communicates, at one end thereof, with the second branched path216, and at the other end, includes a fourth valve741. The fourth valve741is a three-way valve, and is provided for making such switching that a solvent recovery path742and a third solvent supply path743communicate with each other and the solvent path740communicates with either one of the solvent recovery path742or the third solvent supply path743.

The solvent recovery path742communicates with a second recovery container744for recovering a solvent. The second recovery container744has a ventilation pipe745allowing communication between the inside and the outside of the second recovery container744. The third solvent supply path743has a third pump747communicating with a third solvent container746and provided for sending out a solvent stored in the third solvent container746.

In this variation, the second solvent container543stores a solvent capable of extracting the dioxins (the mono-ortho PCBs and the non-DL-PCBs) adsorbing to the alumina layer250, and the third solvent container746stores a solvent capable of extracting the dioxins (the non-ortho PCBs, the PCDDs, and the PCDDs) adsorbing to the adsorbent layer240. The solvent stored in each of the containers543,746can be selected according to the dioxin determination method.

Specifically, in the case of employing the gas chromatography method as the determination method, e.g., toluene or benzene can be used as the solvent stored in the third solvent container746. Alternatively, a solvent mixture obtained in such a manner that an aliphatic hydrocarbon solvent or an organic chlorine-based solvent is added to the toluene or the benzene can be used. In the case of using the solvent mixture, the percentage of the toluene or the benzene is set to equal to or higher than 50% by weight. Examples of the aliphatic hydrocarbon solvent include n-pentane, n-hexane, n-heptane, n-octane, iso-octane, and cyclohexane. Moreover, examples of the organic chlorine-based solvent include dichloromethane, trichloromethane, and tetrachloromethane. Of these extraction solvents, the toluene is specifically preferred because the dioxins, specifically the non-ortho PCBs, the PCDDs, and the PCDFs, can be extracted by use of a small amount of the solvent. On the other hand, not only those similar to the solvent stored in the third solvent container746but also an organic chlorine-based solvent, a solvent mixture of an organic chlorine-based solvent and an aliphatic hydrocarbon solvent, and a solvent mixture obtained by addition of a small amount of toluene to an aliphatic hydrocarbon solvent can be used as the solvent stored in the second solvent container543. However, the toluene is specifically preferred because the dioxins and the PCBs, specifically the mono-ortho PCBs and the non-DL-PCBs, can be extracted by use of a small amount of the solvent.

In the case of employing the bioassay method as the determination method, hydrophilic solvents such as dimethylsulfoxide (DMSO) and methanol can be used as the solvents stored in the second solvent container543and the third solvent container746.

In the method for preparing the analysis sample for the dioxins by means of the preparation apparatus100with the changed second extraction path700, the fourth valve741is, in an initial state, set such that the solvent path740communicates with the third solvent supply path743. Then, after the dioxin fractionating step has been executed as described above, the dioxin extraction step is executed.

At the dioxin extraction step, after each layer of the purification layer220and the fractionating layer230has been dried as described above, the compressor633is stopped, and the fourth valve741is switched such that the solvent path740communicates with the solvent recovery path742on the second extraction path700. Moreover, the second valve520is switched such that the flow path510communicates with the second solvent supply path541on the solvent outflow path500, and the second pump542is actuated. Accordingly, a moderate amount of solvent stored in the second solvent container543is supplied into the pipe body210through the opening212by way of the second solvent supply path541and the flow path510.

The solvent supplied into the pipe body210from the flow path510flows into the second branched path216through the alumina layer250, and is recovered by the second recovery container744through the solvent path740of the second extraction path700. At this point, the solvent dissolves the mono-ortho PCBs and the non-DL-PCBs adsorbing to the alumina layer250, and such a solution with the PCBs, i.e., the first analysis sample, is recovered by the second recovery container744.

At a subsequent step for preparing the analysis sample, after the second pump542has been stopped, the third valve631is switched such that the first ventilation path630and the open path632communicate with each other on the first extraction path600, and the fourth valve741is switched such that the solvent path740communicates with the third solvent supply path743on the second extraction path700. Then, the third pump747is actuated to supply a moderate amount of solvent stored in the third solvent container746into the pipe body210through the second branched path216by way of the third solvent supply path743and the solvent path740.

The solvent supplied into the pipe body210through the second branched path216flows into the first branched path215through the adsorbent layer240, and is recovered by the first recovery container620through the first recovery path610of the first extraction path600. At this point, the solvent dissolves the dioxin group, which adsorbs to the adsorbent layer240, including the non-ortho PCBs, the PCDDs, and the PCDFs, and such a solution with the dioxin group, i.e., the second analysis sample, is recovered by the first recovery container620. The second analysis sample is prepared without the solvent passing through the alumina layer250, and therefore, is fractionated from the mono-ortho PCBs and the non-DL-PCBs with a higher accuracy.

The obtained first analysis sample and the obtained second analysis sample are, as already described, applied to dioxin analysis.

In the preparation apparatus100configured such that the second extraction path700is changed as inFIG. 2, the order of extraction of the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs from the adsorbent layer240and extraction of the mono-ortho PCBs and the non-DL-PCBs from the alumina layer250can be changed at the dioxin extraction step. That is, after the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs has been first extracted from the adsorbent layer240, the mono-ortho PCBs and the non-DL-PCBs can be extracted from the alumina layer250.

Second Embodiment

A second embodiment of an apparatus capable of performing an analysis sample preparation method according to the present invention will be described with reference toFIG. 3. InFIG. 3, a preparation apparatus100is capable of preparing an analysis sample suitable for analysis by a gas chromatography method, and mainly includes a fractionating tool200, a heating apparatus300, a solvent supply apparatus400, a solvent outflow path550, and an extraction path650.

The fractionating tool200is different from the fractionating tool200described in the first embodiment in the structures of a small-diameter portion214and a fractionating layer230of a pipe body210. Specifically, the small-diameter portion214has only a first branched path215as a branched path. The fractionating layer230is configured such that an adsorbent layer240and an alumina layer250are in close contact with each other. Thus, the small-diameter portion214has a shorter length than that of the fractionating tool200described in the first embodiment.

The heating apparatus300and the solvent supply apparatus400are configured as described in the first embodiment.

The solvent outflow path550has a flow path551air-tightly connected to an opening212of the pipe body210. The flow path551has a second valve552. The second valve552is a four-way valve. The second valve552communicates with a discarding path553for discarding a solvent from the pipe body210, a recovery path554for recovering a solvent from the pipe body210, and a supply path555for supplying a solvent to the pipe body210, and makes such switching that the flow path551communicates with any one of the discarding path553, the recovery path554, or the supply path555.

The recovery path554has a solvent recovery container556, and the recovery container556has a ventilation pipe557allowing communication between the inside and the outside of the recovery container556. The supply path555has a second pump558, and communicates with a second solvent container559for storing a dioxin extraction solvent trapped by the fractionating tool200.

The extraction solvent stored in the second solvent container559can dissolve dioxins, and toluene or benzene can be used. Alternatively, a solvent mixture obtained in such a manner that an aliphatic hydrocarbon solvent or an organic chlorine-based solvent is added to the toluene or the benzene can be used. In the case of using the solvent mixture, the percentage of the toluene or the benzene is set to equal to or higher than 50% by weight. Examples of the aliphatic hydrocarbon solvent used for such a solvent mixture include n-pentane, n-hexane, n-heptane, n-octane, iso-octane, and cyclohexane. Moreover, examples of the organic chlorine-based solvent include dichloromethane, trichloromethane, and tetrachloromethane. Of these extraction solvents, the toluene is specifically preferred because the dioxins can be extracted from the fractionating tool200by use of a small amount of the solvent.

The extraction path650has a solvent path651extending from the first branched path215. The solvent path651air-tightly communicates, at one end thereof, the first branched path215, and at the other end, includes a third valve652. The third valve652is a three-way valve. The third valve652communicates with an air supply path653including a compressor654for sending compressed air, a recovery path655for recovering a solvent from the first branched path215, and a supply path656for supplying a solvent to the pipe body210, and makes such switching that the solvent path651communicates with any one of the air supply path653, the recovery path655, or the supply path656.

The recovery path655has a recovery container657for recovering a solvent, and the recovery container657has a ventilation pipe658allowing communication between the inside and the outside of the recovery container657. The supply path656has a third pump659, and communicates with a third solvent container660for storing a dioxin extraction solvent trapped by the fractionating tool200.

The extraction solvent stored in the third solvent container660does not substantially dissolve a dioxin group including non-ortho PCBs, PCDDs, and PCDFs, and exhibits excellent mono-ortho PCBs and non-DL-PCBs dissolubility. For example, an organic chlorine-based solvent, a solvent mixture obtained by addition of an aliphatic hydrocarbon solvent to an organic chlorine-based solvent, or a solvent mixture (a toluene content is normally about 10 to 15% by weight) obtained by addition of toluene to an aliphatic hydrocarbon solvent. The organic chlorine-based solvent used herein is, for example, dichloromethane, trichloromethane, and tetrachloromethane. Moreover, the aliphatic hydrocarbon solvent is, for example, n-pentane, n-hexane, n-heptane, n-octane, iso-octane, or cyclohexane.

Next, the method for preparing the dioxin analysis sample by means of the above-described preparation apparatus100will be described. First, in the preparation apparatus100, a first valve422, an air introduction valve423, the second valve552, and the third valve652are set to prescribed initial states. That is, the first valve422is set to an open state, and the air introduction valve423is set to communicate with a first solvent container410side. Moreover, the second valve552is set such that the flow path551communicates with the discarding path553. Further, the third valve652is set such that the solvent path651communicates with the air supply path653.

Next, after a dioxin fractionating step has been executed as in the first embodiment, each layer of a purification layer220and the fractionating layer230is dried, and a dioxin extraction step is executed. The treatment for drying the purification layer220can be executed as in the first embodiment. In the subsequent treatment for drying the fractionating layer230, the first valve422of the solvent supply apparatus400is switched to a closed state. Then, on the extraction path650, the compressor654is actuated.

By actuation of the compressor654, compressed air is supplied to the first branched path215through the air supply path653and the solvent path651. Such compressed air flows into the flow path551through the opening212by way of the fractionating layer230, and is discharged through the discarding path553. At this point, a solvent remaining in each layer of the fractionating layer230is pushed out by the compressed air, and is discharged from the discarding path553together with the compressed air. As a result, each layer of the fractionating layer230is dried.

At the dioxin extraction step, the second valve552is first switched such that the flow path551communicates with the recovery path554on the solvent outflow path550. Moreover, on the extraction path650, the third valve652is switched such that the solvent path651communicates with the supply path656, and the third pump659is actuated. Accordingly, a moderate amount of solvent stored in the third solvent container660is supplied into the pipe body210through the first branched path215by way of the supply path656and the solvent path651.

The solvent supplied into the pipe body210through the first branched path215passes through the fractionating layer230, and flows into the flow path551and the recovery path554through the opening212. The solvent is recovered by the recovery container556. At this point, the solvent dissolves and extracts the mono-ortho PCBs and the non-DL-PCBs adsorbing to the alumina layer250, and such a solution with the PCBs, i.e., a first analysis sample, is recovered by the recovery container556.

At a subsequent step for extracting the dioxins, the third pump659is stopped, and the third valve652is switched such that the solvent path651communicates with the recovery path655on the extraction path650. Then, on the solvent outflow path550, the second valve552is switched such that the flow path551communicates with the supply path555, and the second pump558is actuated. Accordingly, a moderate amount of solvent stored in the second solvent container559is supplied into the pipe body210through the opening212by way of the supply path555and the flow path551.

The solvent supplied into the pipe body210through the flow path551passes through the alumina layer250and the adsorbent layer240in this order, and flows into the first branched path215. The solvent is recovered by the recovery container657through the solvent path651and the recovery path655of the extraction path650. At this point, the solvent dissolves and extracts the dioxin group, which adsorbs to the adsorbent layer240, including the non-ortho PCBs, the PCDDs, and the PCDFs, and such a solution with the dioxin group, i.e., a second analysis sample, is recovered by the recovery container657.

By the above-described steps, the analysis sample for the mono-ortho PCBs and the analysis sample for the non-ortho PCBs, the PCDDs, and the PCDFs are separately obtained, and each analysis sample is applied to analysis by the gas chromatography method.

Third Embodiment

Another example of a fractionating tool capable of performing an analysis sample preparation method according to the present invention will be described with reference toFIG. 4. In the figure, a fractionating tool200includes a pipe body210having a large-diameter portion213and a small-diameter portion214as in the fractionating tool200used in the preparation apparatus100of the second embodiment. However, the fractionating tool200is divided into the large-diameter portion213and the small-diameter portion214, and the large-diameter portion213and the small-diameter portion214are detachably coupled to each other through a coupling tool800to form the continuous pipe body210.

The large-diameter portion213is formed in a cylindrical shape opening at both ends, and at an end portion on a sulfuric silica gel layer222side, has a neck portion217having the same outer and inner diameters as those of the small-diameter portion214. The small-diameter portion214is formed in a cylindrical shape opening at both ends, and an adsorbent layer240and an alumina layer250are in close contact with each other in a fractionating layer230. The coupling tool800is, for example, formed in a cylindrical shape with a resin material having resistance to various organic solvents, specifically a hydrocarbon solvent, or other materials, and the large-diameter portion213and the small-diameter portion214are liquid-tightly coupled to each other in such a manner that the neck portion217of the large-diameter portion213and an end portion of the small-diameter portion214on an adsorbent layer240side are inserted into the coupling tool800.

When a dioxin analysis sample is prepared using the preparation apparatus100of this example, a dioxin fractionating step is, as in the first embodiment, executed in a state in which the large-diameter portion213and the small-diameter portion214are coupled to each other in the fractionating tool200. The fractionating step can be executed by manual operation. Then, after a purification layer220and the fractionating layer230have been dried subsequently to the fractionating step, the small-diameter portion214is separated from the coupling tool800.

In extraction of dioxins from the fractionating layer230, a solvent not substantially dissolving a dioxin group including non-ortho PCBs, PCDDs, and PCDFs and exhibiting excellent mono-ortho PCBs and non-DL-PCBs dissolubility is, as in the case of the second embodiment, supplied from the end portion of the small-diameter portion214on the adsorbent layer240side. In this manner, mono-ortho PCBs and non-DL-PCBs adsorbing to the alumina layer250are extracted, and a first analysis sample is obtained. Thereafter, a solvent capable of dissolving the dioxins is supplied from an end portion (an opening212) of the small-diameter portion214on an alumina layer250side. In this manner, the dioxin group, which adsorbs to the adsorbent layer240, including the non-ortho PCBs, the PCDDs, and the PCDFs is extracted, and a second analysis sample is obtained.

Such extraction operation can be executed by manual operation, but can be mechanically executed.

Part of a variation of the fractionating tool200of this example is illustrated inFIG. 5. The small-diameter portion214of the fractionating tool200according to this variation is divided into a first portion260filled with the adsorbent layer240and a second portion270filled with the alumina layer250, and the first portion260and the second portion270are detachably coupled to and integrated with each other by a coupling tool810. The coupling tool810is similar to the coupling tool800for coupling the large-diameter portion213and the small-diameter portion214.

The fractionating tool200of this variation is configured so that the small-diameter portion214can be separated from the large-diameter portion213and the small-diameter portion214can be further separated into the first portion260and the second portion270. Thus, when the dioxins are extracted from the fractionating layer230, the operation of extracting the dioxins and the like can be separately executed for the adsorbent layer240of the first portion260and the alumina layer250of the second portion270, and the analysis sample for the mono-ortho PCBs and the non-DL-PCBs and the analysis sample for the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs can be fractionated with a higher accuracy.

OTHER EMBODIMENTS

(1) The fractionating tool200described above in each embodiment is configured such that the silver nitrate silica gel layer221is arranged on the opening211side in the purification layer220, but the order of the silver nitrate silica gel layer221and the sulfuric silica gel layer222can be changed.

Note that in a case where the silver nitrate silica gel layer221and the sulfuric silica gel layer222are interchanged, there is a probability that the non-DL-PCBs with smaller chlorine numbers react with the sulfuric silica gel layer222and the rate of recovery of the non-DL-PCBs with smaller chlorine numbers is lowered in the analysis sample. For this reason, in a case where not only the dioxins but also the non-DL-PCBs with smaller chlorine numbers need to be analyzed (e.g., a case where dioxins in food are analyzed according to the food regulation standards in the EU), the silver nitrate silica gel layer221is preferably arranged on the opening211side in the purification layer220.

(2) The fractionating tool200described above in each embodiment may be configured such that the first active silica gel layer223and the second active silica gel layer224are omitted from the purification layer220.

(3) The large-diameter portion213of the fractionating tool200can be divided into a portion filled with the silver nitrate silica gel layer221and a portion filled with the sulfuric silica gel layer222, and these portions can be coupled to each other upon use. With this configuration, denaturalization of one of the silver nitrate silica gel layer221or the sulfuric silica gel layer222due to influence of the other one of the silver nitrate silica gel layer221or the sulfuric silica gel layer222can be reduced. As a result, the capacity of the purification layer220for purifying the dioxin solution is less likely to be degraded, and therefore, there is a probability that the dioxin recovery rate can be enhanced.

(4) In the dioxin analysis sample preparation method according to each of the above-described embodiments, the purification layer220is heated by the heating apparatus300, but the preparation method according to each embodiment can be similarly performed even in a case where the purification layer220is not heated.

(5) In the dioxin analysis sample preparation method according to each of the above-described embodiments, the treatment for drying the purification layer220and the fractionating layer230can be changed as necessary by any of an air suction method and a compressed air supply method using a compressor. Moreover, the purification layer220and the fractionating layer230can be dried by a nitrogen gas supply. Further, the treatment for drying the purification layer220and the fractionating layer230can be omitted.

EXAMPLES

Hereinafter, the present invention will be specifically described with reference to Examples and the like, but is not limited to these Examples and the like.

Dioxin Solution

A dioxin solution used in the following Examples and the like is as follows.

A standard dioxin substance (a product name “DF-LCS-A” of Wellington Laboratories Inc.), which has a known concentration, of 1 mL and a standard PCBs substance (a product name “PCB-LCS-H” of Wellington Laboratories Inc.), which has a known concentration, of 1 mL were added to and dissolved in n-hexane of 100 mL, and the resultant was taken as a standard dioxin solution. The standard dioxin substance includes PCDDs, PCDFs, and DL-PCBs labelled by 13C12. The standard PCBs substance includes seven types of non-DL-PCBs which are labelled by 13C12 and of which IUPAC numbers are #28, #52, #101, #138, #153, #170, and #180. Of these substances, six types of PCBs isomers (PCBs isomers with chlorine numbers of 3 to 7) with #28, #52, #101, #138, #153 and #180 are targeted for food regulations in the EU.

Environmental Sample Solution A:

A Soxhlet extraction method using toluene as an extraction solvent was applied to fly ash, which had been collected from a general waste incineration facility, of 0.3 g, and in this manner, a toluene extract was obtained. The toluene was removed from the toluene extract, and the residue thereof was dissolved in n-hexane. In this manner, a hexane solution of 2 mL was prepared. A standard solution of 0.02 mL was added to the total amount of the hexane solution, and the resultant was taken as an environmental sample solution A.

Environmental Sample Solution B:

Operation was performed as in preparation of the environmental sample solution A, except that soil, which had been collected from a factory site, of 5 g was used instead of fly ash of 0.3 g. The resultant solution was taken as an environmental sample solution B.

Environmental Sample Solution C:

Operation was performed as in preparation of the environmental sample solution A, except that a bottom material, which had been collected from a river, of 5 g was used instead of fly ash of 0.3 g. The resultant solution was taken as an environmental sample solution C.

Environmental Sample Solution D:

Operation was performed as in preparation of the environmental sample solution A, except that sludge, which had been collected from a sewage treatment facility, of 5 g was used instead of fly ash of 0.3 g. The resultant solution was taken as an environmental sample solution D.

Simulant Environmental Sample Solution:

Toluene of 100 μL was added to a standard solution of 0.02 mL, and the resultant is taken as a simulant environmental sample solution.

Food Sample Solution A:

A standard solution of 0.02 mL was added to sunflower oil (a product name “S5007” of Merck) of 3 g, and the resultant was taken as a food sample solution A.

Food Sample Solution B:

Operation was performed as in preparation of the environmental sample solution A, except that an oil content, which had been extracted using an organic solvent from freeze-dried pork, of 3 g was used instead of fly ash of 0.3 g. The resultant solution was taken as a food sample solution B.

Filler

A filler used in a fractionating tool in the Examples and the like below is as follows.

Silver Nitrate Silica Gel:

The total amount of an aqueous solution obtained in such a manner that silver nitrate (manufactured by Wako Pure Chemical Corporation) of 11.2 g is dissolved in distilled water of 30 mL was added to active silica gel (manufactured by Kanto Chemical Co., Inc.) of 100 g, and was uniformly mixed. Silver nitrate silica gel was used, which was prepared in such a manner that the resultant active silica gel is heated to 70° C. under a reduced pressure by means of a rotary evaporator and is dried.

Concentrated sulfuric acid (manufactured by Wako Pure Chemical Corporation) of 78.7 g was uniformly added to active silica gel (manufactured by Kanto Chemical Co., Inc.) of 100 g. Thereafter, the resultant was dried to prepare sulfuric silica gel.

Activated carbon-containing silica gel was used, which was obtained in such a manner that activated carbon (a product name “Kuraray Coal PK-DN” of Kuraray Co., Ltd.) is added to active silica gel (manufactured by Kanto Chemical Co., Inc.) and is uniformly mixed. The content of the activated carbon was set to 0.018% by weight or 3.0% by weight.

Graphite-containing silica gel was used, which was obtained in such a manner that graphite (a product name “ENVI-Carb” of Sigma-Aldrich) is added to active silica gel (manufactured by Kanto Chemical Co., Inc.) and is uniformly mixed. The content of the graphite was set to 12.5% by weight.

A product name “ENVI-Carb” of Sigma-Aldrich was used.

A product name “Florisil, 75 to 150 μm” of Fujifilm Wako Pure Chemical Corporation was used.

Magnesium silicate (a product name “Florisil, 75 to 150 μm” of Fujifilm Wako Pure Chemical Corporation) activated by heating for two hours under a nitrogen air flow set to a flow rate of 0.5 to 1.0 L/minute in a tubular furnace was used. A heating treatment temperature was as shown in Table 1 described later.

Graphite (“ENVI-Carb” of Sigma-Aldrich) was added to magnesium silicate (a product name “Florisil, 75 to 150 μm” of Fujifilm Wako Pure Chemical Corporation), and was uniformly mixed. In this manner, a mixture was prepared. The resultant from heating of the mixture for two hours in a nitrogen air flow set to a flow rate of 0.5 to 1.0 L/minute in a tubular furnace was used. The content of the graphite in the mixture and the temperature of heating of the mixture are as shown in Table 1 described later.

Graphite (“ENVI-Carb” of Sigma-Aldrich) heated for two hours in a nitrogen air flow set to a flow rate of 0.5 to 1.0 L/minute in a tubular furnace set to 450° C. was added to magnesium silicate (a product name “Florisil, 75 to 150 μm” of Fujifilm Wako Pure Chemical Corporation) separately activated by heating for two hours in a nitrogen air flow set to a flow rate of 0.5 to 1.0 L/minute in a tubular furnace, and was uniformly mixed. The resultant mixture was used. The temperature of heating of the magnesium silicate and the content of the graphite are as shown in table 1 described later.

A product name “Aluminum Oxide 90 active basic-(activity stage I) for column chromatography” (a particle size of 0.063 to 0.200 mm) of Merck was used.

Examples 1 to 16 and Comparative Examples 1 to 6

An analysis sample was prepared from a dioxin solution by means of the dioxin analysis sample preparation apparatus illustrated inFIG. 1. The specifications of the fractionating tool used in the preparation apparatus are as follows.

In a large-diameter portion of a pipe body set to an outer diameter of 18.5 mm, an inner diameter of 12.5 mm, and a length of 200 mm, silver nitrate silica gel of 4.4 g (a filling height of 60 mm) was stacked on sulfuric silica gel of 8.5 g (a filling height of 80 mm) to form a purification layer as illustrated inFIG. 1(a stack of a first active silica gel layer and a second active silica gel layer is omitted).

In a small-diameter portion of the pipe body set to an outer diameter of 8 mm, an inner diameter of 6 mm, and a length of 100 mm, an adsorbent layer and an alumina layer was formed as illustrated inFIG. 1. Each of the adsorbent layer and the alumina layer is formed by filling of a material shown in Table 1. Table 1 shows Comparative Examples corresponding to Examples.

In dioxin analysis sample preparation operation, a dioxin solution of about 4 mL was added to the silver nitrate silica gel layer of the purification layer, and the purification layer was heated to 60° C. Then, n-hexane of 90 mL was gradually supplied to the purification layer such that the n-hexane passes through the purification layer and the fractionating layer. After the n-hexane has passed through the fractionating layer, compressed air passes through the fractionating layer to dry the fractionating layer. Then, the alumina layer in the fractionating layer was heated to 90° C., toluene of 1.0 mL was supplied to the alumina layer from an opening side at a lower end of the pipe body, and the toluene having passed through the alumina layer was recovered through a second branched path. In this manner, a first analysis sample was obtained. Next, the adsorbent layer in the fractionating layer was heated to 90° C., toluene of 1.5 mL was supplied to the adsorbent layer through the alumina layer from the opening side at the lower end of the pipe body, and the toluene having passed through the adsorbent layer was recovered through a first branched path. In this manner, a second analysis sample was obtained. Time required until the second analysis sample is obtained after addition of the dioxin solution was about two hours in any of Examples and Comparative Examples.

Each of the first analysis sample and the second analysis sample was separately quantitatively analyzed by a HRGC/HRMS method, and the rate of recovery of dioxins and non-DL-PCBs was calculated. The dioxin recovery rate indicates the percentage (%) of the amount of dioxins contained in the analysis sample with respect to the amount of dioxins contained in the dioxin solution added to the purification layer. The same also applies to the rate of recovery of the non-DL-PCBs. Results are shown in Tables 2 to 7. In Tables 2 to 7, “-” indicates that no recovery rate was calculated.

Regarding the dioxin solutions used in Examples 1 to 15, it is shown that each dioxin contained therein was recovered within a range of 60 to 120% as the regulation standards (COMMISSION REGULATION (EU) No 709/2014) in the European Union (EU) and is fractionated into a dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs with a high accuracy. In Examples 13 and 14 where the dioxin solutions are those derived from food (the food sample solutions A, B), the rate of recovery of the non-DL-PCBs targeted for the food regulations in the EU is high.

In Example 16, there is a defect in the non-ortho PCBs recovery rate of the second analysis sample. It is assumed that this is because the dioxin solution is a solution (the environmental sample solution A) containing impurity components in an environmental sample (the fly ash) and influence of these impurity components, specifically an aromatic hydrocarbon compound, is provided. On the other hand, in Examples 8 to 12, the first analysis sample and the second analysis sample were prepared from a dioxin solution (the environmental sample solutions A to D and the simulant environmental sample solution) containing impurity components in an environmental sample as in Example 16, but the graphite-mixed active magnesium silicate used in the adsorbent layer was one obtained by heating of the mixture of the magnesium silicate and the graphite. Thus, the non-ortho PCBs recovery rate of the second analysis sample is high, and the accuracy of fractionation into the dioxin group including the non-ortho PCBs, the PCDDs, and the PCDFs and the mono-ortho PCBs is high.

Comparative Examples 7 to 11

In the dioxin analysis solution preparation apparatus illustrated inFIG. 1and used in Examples 1 to 16 and Comparative Examples 1 to 6, an adsorbent layer portion of the fractionating layer was, as shown in Table 8, changed to a double-layer stack of an upper layer and a lower layer. Moreover, in Comparative Example 11, no alumina layer was provided.

Using the preparation apparatus changed as described above, the dioxin analysis sample preparation operation was executed as in Examples 1 to 16 and Comparative Examples 1 to 6. Each of the obtained first analysis sample and the obtained second analysis sample was separately quantitatively analyzed by the HRGC/HRMS method, and the rate of recovery of dioxins and non-DL-PCBs was calculated. Results are shown in Table 9. In Table 9, “-” indicates that no recovery rate was calculated.

According to Table 9, the fractionating tools of Comparative Examples 7 to 10 with the same adsorbent layer can fractionate the dioxins with a high accuracy in a case where the dioxin solution is a food sample solution. In a case where the dioxin solution is an environmental sample solution containing an aromatic hydrocarbon compound as an impurity component, non-ortho PCBs trapping performance in the adsorbent layer is degraded, and as a result, the dioxin fractionating accuracy is degraded.

LIST OF REFERENCE NUMERALS