JP3670909B2 - Sample preparation method - Google Patents

Description

【０１０３】
これらのガスクロマトグラフ条件は、ダイオキシン類の10種類の親イオン（4-8塩素化ダイオキシン及び4-8塩素化ジベンゾフラン）が完全に分離された状態で質量分析計に導入されるように設定されている。
比較例１
スチレンジビニルベンゼンフィルタとしては、市販のディスクフィルタを用いた。桐山ロート或いは同等の器具にフィルタを保持し、下に受け器を置いた。試料をロードし、受け器側を負圧にすることにより通液する。通液後、少量のアセトンをディスクフィルタに通してダイオキシン類を溶出した。
【０１０４】
焼却場周辺から採取した土壌サンプルを高温高圧溶媒抽出装置ASE-200（ダイオネクス社製）を用いて、トルエンにより、土壌中の有機物を抽出した。試料中に残存している水分を除去するため、試料と同等量の無水硫酸ナトリウムを均一に混合した。圧力を120気圧以上，温度を120℃以上に上げ、ダイオキシン類を抽出した。抽出効率を向上させるため、2回抽出を行った。得られた有機物をエバボレーターで約１ｍｌに濃縮し、ダイオキシン類のトルエン抽出液を得た。
【０１０５】
このトルエン抽出液をＧＣ／ＭＳ／ＭＳ分析に供した。分析妨害物質が検出され、ＧＣ／ＭＳ／ＭＳ分析ができなくなった。
実施例１
スチレンジビニルベンゼンフィルタとしては、市販のディスクフィルタを用いた。桐山ロート或いは同等の器具にフィルタを保持し、下に受け器を置いた。試料をロードし、受け器側を負圧にすることにより通液する。通液後、少量のアセトンをディスクフィルタに通してダイオキシン類を溶出した。
【０１０６】
焼却場周辺から採取した土壌サンプルを高温高圧溶媒抽出装置ASE-200（ダイオネクス社製）を用いて、トルエンにより、土壌中の有機物を抽出した。試料中に残存している水分を除去するため、試料と同等量の無水硫酸ナトリウムを均一に混合した。圧力を120気圧以上，温度を120℃以上に上げ、ダイオキシン類を抽出した。抽出効率を向上させるため、2回抽出を行った。得られた有機物をエバボレーターで濃縮し、ダイオキシン類のトルエン抽出液を得た。
【０１０７】
一方、バリアン社からExtubeとして市販されている珪藻土カラム中の珪藻土の保持体積の約８０％の体積の濃度９８％の硫酸を流し、３０分間放置して、珪藻土の表面を硫酸で処理した。次いで、この硫酸処理された珪藻土カラムに、前記トルエン抽出液を添加し、１０分間放置した。そして、ジクロロメタンを用いてダイオキシン類を溶出し、次いで、シリカゲルカラムを通した。次いで、エバボレーターで濃縮し、ジクロロメタン抽出液を得た。このジクロロメタン抽出液をシリカゲルカラムに添加し、トルエンを用いて溶出した。次いで、エバポレーターで濃縮し、トルエン溶液を得た。このトルエン溶液をＧＣ／ＭＳ／ＭＳ分析に供した。
【０１０８】
トルエン溶液を２００μｌにまで濃縮した場合であっても、分析妨害物質に妨害されることなく、分析することができた。比較例１と比べて、濃縮率が５倍になり、より低感度まで分析可能になった。
実施例２
焼却場から排出される飛灰について、サンプル中のダイオキシン類の回収率を求めた。なお、飛灰は、土壌と比べて、マトリックスが少ない。
【０１０９】
飛灰について、比較例１と同様に処理して、ダイオキシン類の量を調べた。一方、飛灰について、実施例１と同様に処理して、ダイオキシン類の量を調べた。即ち、比較例１の方法では、硫酸処理珪藻土カラム、シリカゲルカラムの何れでも処理されていないのに対して、実施例１の方法では、硫酸処理珪藻土カラム及びシリカゲルカラムで処理されていることが異なる。
【０１１０】
硫酸処理珪藻土カラム及びシリカゲルカラムの処理がされなかった場合を基準として、硫酸処理珪藻土カラム及びシリカゲルカラムの処理がされた場合のダイオキシン類の回収率を求めた。２，３，７，８−テトラクロロポリクロロジベンゾ−ｐ−ダイオキシン（Ｔ４ＣＤＤ）の回収率の平均は９７％、１，２，３，７，８−ペンタクロロポリクロロジベンゾ−ｐ−ダイオキシン（Ｐ５ＣＤＤ）の回収率の平均は１１０％、ヘキサクロロポリクロロジベンゾ−ｐ−ダイオキシン類（Ｈ６ＣＤＤｓ）の回収率の平均は８７％、１，２，３，４，６，７，８−ヘプタクロロポリクロロジベンゾ−ｐ−ダイオキシン（Ｈ７ＣＤＤ）の回収率の平均は８７％、１，２，３，４，５，６，７，８−オクタクロロポリクロロジベンゾ−ｐ−ダイオキシン（Ｏ８ＣＤＤ）の回収率の平均は９４％であった。
【０１１１】
この結果は、本発明の前処理方法の回収率は高く、感度向上に有効であることが示された。
以下の実施例３〜５では、実施例１の前処理がされたサンプルをイオントラップ質量分析計を用いたＧＣ／ＭＳ／ＭＳで分析した。
実施例３
日本国内のある焼却場周辺から土壌を採取し、次いで、アルカリ触媒処理してダイオキシン類の濃度を低減させた土壌をサンプルに用いた。この定量下限値付近の土壌に対して、ポリクロロＤＤ及びポリクロロＤＦについて定量した。
【０１１２】
その結果を表１に示す。
【０１１３】
【表１】

【０１１４】
表中、ＣＤＤは、クロロジベンゾ−ｐ−ダイオキシン、ＣＤＦはクロロジベンゾフランを意味する。Ｔ４、Ｐ５、Ｈ６、Ｈ７、Ｏ８は、それぞれ、テトラ、ペンタ、ヘキサ、ヘプタ、オクタを意味する。以下、同様である。
【０１１５】
従来法と本発明方法の定量値は非常に良く一致していた。本発明方法では、各異性体毎に1pg/gまで定量することができた。その結果、10pg-TEQ/g程度の土壌サンプルを定量することが可能になった。
【０１１６】
なお、ＴＥＱとは下記の通りである。一つのサンプル中には、通常、ポリクロロジベンゾ−ｐ−ダイオキシン類の種々の異性体が存在する。そして、各々の異性体でその毒性が異なる。そこで、サンプル中の種々の異性体の毒性の総量を、２，３，７，８−ＴｅＣＤＤの毒性に換算した値をTEQという。TEQが８．０ｎｇ−ＴＥＱ／ｇということは、１ｇのサンプル中に８．０ｎｇの２，３，７，８−ＴｅＣＤＤが含まれているのと同等の量のポリクロロジベンゾ−ｐ−ダイオキシン類又はポリクロロジベンゾフラン類が含まれているということである。
実施例４
外国の化学工場跡地から高濃度のダイオキシン類を含有する土壌を採取した。この高濃度汚染土壌に対して、ポリクロロＤＤ及びポリクロロＤＦについて定量した。実験結果を表２に示す。
【０１１７】
従来法による定量は、A及びBの二つのそれぞれ独立した分析機関によって行われた。表２から分かるとおり、高濃度サンプルに対しても従来法と本発明方法の定量値は非常に良く一致していた。本発明方法では、10ng-TEQ/g程度の土壌サンプルを定量することが可能であった。
【０１１８】
【表２】

【０１１９】
実施例５
内部標準物質の質量クロマトグラムを図４に示す。即ち、２，３，７，８−テトラクロロポリクロロジベンゾ−ｐ−ダイオキシン（Ｔ４ＣＤＤ）、１，２，３，７，８−ペンタクロロポリクロロジベンゾ−ｐ−ダイオキシン（Ｐ５ＣＤＤ）、ヘキサクロロポリクロロジベンゾ−ｐ−ダイオキシン類（Ｈ６ＣＤＤｓ）、１，２，３，４，６，７，８−ヘプタクロロポリクロロジベンゾ−ｐ−ダイオキシン（Ｈ７ＣＤＤ）、１，２，３，４，５，６，７，８−オクタクロロポリクロロジベンゾ−ｐ−ダイオキシン（Ｏ８ＣＤＤ）の混合物についてのクロマトグラムである。各々のポリクロロジベンゾ−ｐ−ダイオキシンの注入量は、30pgであった。
【０１２０】
ヘキサクロロDDsで若干のベースラインの乱れがあるものの、定量には影響の無いレベルである。またその他のピークは、不純物の影響を受けていない。これより、本発明方法では、土壌サンプル中のダイオキシン類に対して十分選択性が高いことが示唆される。
【０１２１】
【発明の効果】
珪藻土カラムを用いることにより、自然滴下で硫酸を珪藻土にコーティングすることが可能になった。これにより、分析作業ステップが減り、作業時間ひいては分析時間が短縮された。
【０１２２】
更に、作業者が硫酸と接するのはカラムに硫酸をロードするときだけなので、安全性が向上した。
【図面の簡単な説明】
【図１】イオントラップ質量分析計を用いたＧＣ／ＭＳ／ＭＳ装置の一実施態様の説明断面図である。
【図２】図１の装置の質量分析部の説明断面図である。
【図３】質量分析部の電圧制御を示す説明図である。
【図４】内部標準物質の質量クロマトグラムである。
【図５】図５は、本発明の一実施態様で得られた質量クロマトグラムを示す。
【図６】図６は、一つのクロマトピークに対応する生成物イオンのイオン質量分布を示す質量スペクトルである。
【図７】図７は、別個のクロマトピークに対応するイオン質量分布を示す生成物イオンの質量スペクトルである。
【図８】図８は、従来のＧＣ／ＭＳの前処理のフローシートを示す。
【符号の説明】
１０…ガスクロマトグラフィー部、１２…シリンジ、１４…オーブン、１６…カラム、１８…出口、２０…イオン源部、２２…真空チャンバ、２４…イオン化装置、２６…通路、２８ａ、２８ｂ、２８ｃ…レンズ、３０…質量分析部、３２…リング電極、３３…エンドキャップ、３４…エンドキャップ、３５…トラップ電圧発生器、３６…解離電圧発生器、３７…トラップチャンバ、４０…イオン検出部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sample pretreatment method, and more particularly to a sample pretreatment method containing a halogenated aromatic organic compound. The pretreatment method of the present invention is particularly suitable for pretreatment of analytical methods such as GC / MS and GC / MS / MS.
[0002]
[Prior art]
Mass spectrometry refers to an analysis method based on a mass spectrum, and mass spectrum refers to a record of a series of ion masses and intensities generated by an analyte being ionized by some method. The mass spectrum records the ionic mass of the product that the molecule has decomposed with ionization, typically the x-axis indicates the ionic mass and the y-axis records the intensity of each ionic mass. Here, since the generated fragment ions depend on the molecular structure of the analysis target (analyte), the molecular structure can be determined based on the mass spectrum or the molecule can be specified. For example, when the analysis object in the sample is ionized as it is, the molecular weight of the analysis object can be obtained directly.
[0003]
It is known that when a sample is a mixture, various components in the sample are separated by chromatography and each peak is further analyzed by a mass spectrometer. For example, in GC / MS, a sample is separated by gas chromatography (GC) and then analyzed by a mass spectrometer. In LC / MS, the sample is separated by liquid chromatography (LC) and then by a mass spectrometer.
[0004]
For example, if two or more analytes are included in a sample, each analyte is chromatographed into separate peaks, mass analyzed for each peak, and each analyte is Can be identified.
[0005]
Tandem mass spectrometry is an analysis method combining two or more mass spectrometry, and is often abbreviated as MS / MS. Typically, various ions are separated by mass in the first stage mass analysis and identified by the mass of the ions in the second stage mass analysis. For example, various precursor ions are generated in the first stage mass spectrometry. Next, product ions derived from the precursor ions are generated. Finally, the mass spectrum of the product ions is recorded in the second stage mass analysis.
[0006]
In tandem mass spectrometry, various methods are used when generating product ions from precursor ions. For example, specific precursor ions may be separated from various precursor ions, and product ions derived from the specific precursor ions may be analyzed by second-stage mass spectrometry. In this case, as the precursor ions, so-called metastable ions that satisfy certain conditions regarding the magnetic field, the orbit radius, and the like may be separated. Alternatively, precursor ions may be activated inside the chamber and fragmented to obtain product ions. For example, the precursor ions may be fragmented by colliding with other species such as neutral atoms (He, Ar). In this collision, in order to promote the collision between the precursor ions and the species, the electromagnetic field or the like may be regularly changed to cause a certain kind of resonance.
[0007]
In tandem mass spectrometry, a triple stage quadrapole mass spectrometer, an ion trap mass spectrometer, an ion cyclotron mass spectrometer, and the like are used. A triple stage quadrapole mass spectrometer combines two or more quadrupole mass spectrometers. On the other hand, the ion trap mass spectrometer and the ion cyclotron type mass spectrometer can be used for independent mass spectrometry or tandem mass spectrometry depending on the ion scanning method.
[0008]
In an ion trap mass spectrometer, by controlling conditions such as voltage, only ions having a specific range of mass are captured in the trap chamber, and ions having a mass outside the range are discharged from the trap chamber. And the discharged | emitted ion is detected by detection means, such as a photoelectron amplifier tube. If desired, the mass range of trapped ions can be varied to eject only specific mass ions or only specific mass range ions to obtain a mass spectrum for the ejected ions. That is, by changing conditions such as voltage, ions in a certain mass range from the inside of the trap chamber can be stabilized and other ions can be destabilized. Accordingly, the destabilized ions are detected by the detection device. For example, by scanning a voltage or the like within a predetermined range, ions are destabilized according to a predetermined law, and mass spectra can be sequentially detected for these ions.
[0009]
Regarding the ion trap mass spectrometer, JP-B-60-32310, JP-B-3-59547, JP-B-8-21365, Japanese Patent No. 2716696, JP-A-62-276739, JP-B-4-49219, Patent No. 2608100, Japanese Patent Publication No. 5-69256, JP-A-2-103856, Japanese Patent No. 2729007, Japanese Patent No. 2598602, Japanese Patent No. 2703724, and Japanese Patent No. 2658012, and all these documents Is hereby incorporated by reference.
[0010]
An ion trap mass spectrometer can be used for tandem mass spectrometry by generating precursor ions by fragmenting precursor ions while trapping precursor ions. It is also possible to further combine GC / MS and MS / MS, and is generally abbreviated as GC / MS / MS. One aspect of the present invention relates to performing GC / MS / MS using an ion trap tandem mass spectrometer.
[0011]
Here, a generic name other than the analyte in the sample is called a matrix. For example, when performing GC / MS / MS with an ion trap mass spectrometer, a mixture of a sample and a solvent is injected into the GC. The solvent is typically selected so as to dissolve all the sample. The sample is composed of an analysis object (for example, TeCDD) and a matrix. In the ionization of GC / MS / MS, not only the sample and the solvent but also the carrier gas in GC is ionized.
[0012]
[Problems to be solved by the invention]
In order to perform GC / MS or GC / MS / MS on a sample, it was required to pre-process the sample. In particular, samples collected from the environment (for example, smoke; wastewater; incinerated ash; soil; food such as meat, fish, vegetables, etc .; animals and plants) contain various substances in addition to the analyte. Yes. And since a certain kind of substance also interferes with the analysis, it is desirable to remove as much as possible other than the analyte.
[0013]
For example, tetrachlorodibenzo-p-dioxin (TeCDD) and tetrachlorodibenzofuran (TeCDF) are conventionally separated and quantified by GC / MS. And in order to remove the substance used as noise in a chromatogram, the very complicated pretreatment was required and it usually took 1 week to 10 days only for pretreatment. And including pre-processing and measurements, it takes 2-3 weeks.
[0014]
FIG. 8 shows a conventional flow sheet for GC / MS pretreatment. Here, drainage is used as a sample. The drainage sample is filtered through a glass fiber filter (pore size 1μm) and separated into filtrate and solids. Extract twice with 100 ml of dichloromethane per 1 L of filtrate. The solid content is dehydrated with acetone and then subjected to Soxhlet extraction with toluene for at least 16 hours. Thereafter, the extract is concentrated through sulfuric acid treatment, purification using a silica gel column, and purification using an alumina column, and analyzed by GC / MS.
[0015]
In this sulfuric acid treatment, one of the following three methods is usually used.
1) Add concentrated sulfuric acid to the dioxin-containing organic solvent, stir and separate.
2) Coat the silica gel with concentrated sulfuric acid. Usually mixed in a beaker or flask. A silica column coated with sulfuric acid is packed into a glass column, and a dioxin-containing organic solvent is passed therethrough.
[0016]
3) Concentrated sulfuric acid and silica gel are mixed in a beaker or flask, and then an organic solvent containing dioxins is added and mixed. Thereafter, the organic solvent layer is removed with a rotary evaporator. The treated silica gel is packed in a column and an organic solvent is passed through to extract dioxins.
[0017]
1) is an old method. The operation was complicated and only one sample could be processed at a time. In addition, since concentrated sulfuric acid is handled directly, skill in analysis work is required from the viewpoint of safety.
[0018]
2) is an improved method of 1). The worker contacts the sulfuric acid only at the stage of coating the sulfuric acid in the beaker. If a plurality of columns are juxtaposed, a plurality of samples can be processed simultaneously. However, since the process of coating sulfuric acid and column chromatography are performed separately, one additional work step is required. In addition, skill in operation was required for filling the glass column.
[0019]
3) is an intermediate processing method between 1) and 2). Since the sample is also processed at the same time as the sulfuric acid treatment of silica gel, there is only one work step. Moreover, it is also possible to coat sulfuric acid simultaneously with solvent removal using a rotary evaporator. However, there are many subsequent work processes such as extraction, and there is a problem that it takes time to remove the solvent. Furthermore, in order to handle concentrated sulfuric acid directly in the same way as 1), skill in analytical work was required.
[0020]
After the sulfuric acid treatment, silica gel was used for the stationary phase of the liquid chromatography column. When sulfuric acid was passed through this silica gel column, sulfuric acid did not pass through the column because of the high viscosity of sulfuric acid. Alternatively, even if sulfuric acid passes through the column, it takes a practically unrealistic time, such as one day or more. Therefore, conventionally, it has been necessary to use sulfuric acid in a container such as a beaker or a flask.
[0021]
For analysis of tetrachlorodibenzo-p-dioxins contained in environmental samples by GC / MS / MS using an ion trap method, Jeffry Blaise Plomley et al, Organic Mss Spectroscopy, Vol. 29, 372-381, (1994) "Rapid Screening Technique for Tetrachlorodibenzo-p-dioxins in Complex Environmental Matrices by Gas Chromatography / Tandem Mass Spectrometry with an Ion-trap Detector".
[0022]
However, this document does not describe adjusting the auxiliary voltage in order to generate desired product ions inside the trap chamber. In this document, precursor ions are generated inside the trap chamber. In this case, precursor ions and generated product ions coexist in the trap chamber, and various peaks appear in the obtained mass spectrum.
[0023]
[Means for Solving the Problems]
The present inventor has found that diatomaceous earth carries sulfuric acid, and that sulfuric acid acts as a stationary phase for liquid chromatography, and that sulfuric acid carried on diatomaceous earth decomposes an analysis interfering substance.
[0024]
In the first aspect of the present invention, flowing sulfuric acid through a column for liquid chromatography filled with diatomaceous earth, treating the diatomaceous earth with sulfuric acid, and then flowing the sample in liquid form through the column for liquid chromatography. A featured sample pretreatment method is provided.
[0025]
In the present invention, it is preferable to perform chromatography using an inorganic oxide as a stationary phase on the liquid that has passed through the diatomaceous earth treated with sulfuric acid.
In a second aspect of the present invention, the method includes a step of mixing a sample and sulfuric acid to obtain a liquid mixture, and a step of flowing the liquid mixture through a liquid chromatography column filled with diatomaceous earth. A sample pretreatment method is provided.
[0026]
In the present invention, the sample preferably contains a halogenated aromatic organic compound.
In another aspect of the present invention, there is provided an analysis method for further analyzing a sample pretreated by the above method by GC / MS.
[0027]
In another aspect of the present invention, there is provided an analysis method in which the sample pretreated by the above method is further analyzed by GC / MS / MS.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
One embodiment of the present invention is a pretreatment for detecting in a subsequent analysis an analyte that is not substantially altered by sulfuric acid. Analytes in the sample are not substantially altered by sulfuric acid and are detected in subsequent analyses. On the other hand, since at least a part of ordinary interfering substances such as organic substances is decomposed or sulfonated with sulfuric acid, it is easy to remove or difficult to interfere with detection of the analyte. . In the case where the analysis object is a salt, even if the analysis object is changed to sulfate by sulfuric acid, the counter ion is not changed, so that it does not substantially change.
[0029]
For example, polychlorodibenzo-p-dioxins, polychlorodibenzofurans, polychlorobiphenyls, chlorinated naphthalene and the like are not decomposed by sulfuric acid. In contrast, olefins, alcohols, amines and the like are oxidized with sulfuric acid.
[0030]
The analysis target preferably contains a halogenated aromatic organic compound. Halogen refers to fluorine, chlorine, bromine, or iodine.
The analysis object preferably contains polychlorodibenzo-p-dioxins and polychlorodibenzofurans, and the analysis object further includes polychlorodibenzo-p-dioxins, polychlorodibenzofurans and polychlorinated biphenyls. It is more preferable that the product is included.
[0031]
In one embodiment of the present invention, sulfuric acid is passed through a liquid chromatography column packed with diatomaceous earth, and the diatomaceous earth is treated with sulfuric acid. Diatomaceous earth is composed of a large number of fine crystal grains and can adsorb water, sulfuric acid, etc. on its surface. In addition, pores are formed in the diatomaceous earth for flowing sulfuric acid, organic solvent, and the like. While not intending to be bound by any particular theory for the present invention, it is believed that by flowing sulfuric acid, the pore facing surface is coated with sulfuric acid. Also, diatomaceous earth supports sulfuric acid, and sulfuric acid can act as a stationary phase for liquid chromatography.
[0032]
Conventionally, silica gel has been used for the stationary phase of liquid chromatography columns. When sulfuric acid was passed through this silica gel column, sulfuric acid did not pass through the column due to the high viscosity of sulfuric acid. Alternatively, even if sulfuric acid passes through the column, it takes a practically unrealistic time, such as one day or more.
[0033]
On the other hand, in the column filled with diatomaceous earth, even if it is concentrated sulfuric acid, concentrated sulfuric acid can flow through the column by natural dripping, so that the diatomaceous earth in the column can be coated. Therefore, it is not necessary to coat silica gel in a beaker or flask as in the conventional method, and the operation is simplified. That is, since a predetermined volume of concentrated sulfuric acid having a predetermined concentration is added to a predetermined diatomaceous earth column, the operation is simplified, and as a result, the entire operation time is shortened. Furthermore, safety was improved because the worker only contacted the sulfuric acid when loading the column with sulfuric acid.
[0034]
In one embodiment of the present invention, sulfuric acid supported on diatomaceous earth becomes the stationary phase for liquid chromatography. In the present specification, liquid chromatography includes liquid-liquid partition chromatography and liquid-liquid extraction chromatography. As a column for liquid chromatography filled with diatomaceous earth, for example, a commercially available diatomaceous earth column for liquid-liquid extraction can be used. In a liquid-liquid extraction column, liquid-liquid extraction using a separatory funnel can be substituted, and operations of shaking, centrifugation, and sorting are not required.
[0035]
Diatomaceous earth has the property that it retains polar substances and does not retain nonpolar substances, as is the case with conventionally used silica gels. As the diatomaceous earth column, for example, Extube commercially available from Varian can be suitably used.
[0036]
The concentration of sulfuric acid is preferably 80% by weight or more, more preferably 90% by weight or more, still more preferably 95% by weight or more, and 98% by weight or more. It is particularly preferred. This is because as the concentration of sulfuric acid increases, it becomes easier to decompose the interfering substances.
[0037]
In general, diatomaceous earth filled in a liquid chromatography column has a volume that can hold water uniquely. In a commercially available diatomite column, this retention volume is usually described in an instruction manual or the like. It is preferable to flow 50-100% of the sulfuric acid volume to the column, more preferably 60-95% sulfuric acid to the column, and 70-95% sulfuric acid to the column. It is still more preferred that 80 to 95% volume of sulfuric acid is passed through the column. This is because when sulfuric acid having a volume larger than 100% of the holding volume is passed through the column, excess sulfuric acid flows out of the column, and the sulfuric acid needs to be neutralized and discarded. On the other hand, when a volume of sulfuric acid smaller than 50% of the holding volume is passed through the column, the efficiency decreases.
[0038]
It is preferable that the sulfuric acid is allowed to stand for a short period after flowing through the diatomaceous earth column. This period depends on the temperature and the column size and is appropriately selected. For example, it is preferably left for 1 minute to 24 hours, more preferably 5 minutes to 2 hours, and still more preferably 10 minutes to 1 hour. While allowed to stand, it appears that the sulfuric acid is reliably coated with diatomaceous earth.
[0039]
If desired, the diatomaceous earth column may be washed with an organic solvent, in particular a dry organic solvent, before flowing sulfuric acid through the diatomaceous earth column.
On the other hand, it is not preferable to flow water through the diatomaceous earth column before flowing sulfuric acid through the diatomaceous earth column. This is because, instead of sulfuric acid, water is retained on the surface of the diatomaceous earth column, making it difficult to retain sulfuric acid. Therefore, when storing a commercially available diatomaceous earth column, it is preferable to take care not to adsorb water to the diatomaceous earth in the presence of a desiccant such as silica gel. The diatomaceous earth may be dried before flowing sulfuric acid through the diatomaceous earth column. For example, suction may be performed under reduced pressure while heating the diatomaceous earth column.
[0040]
Moreover, you may wash | clean the diatomaceous earth column processed with the sulfuric acid with the organic solvent as needed. As the organic solvent for washing, for example, a halogenated organic compound such as dichloromethane can be used. It is preferable to remove the organic solvent after washing. For example, the liquid chromatography column may be removed by being pressurized with a plunger or the like from the upper part. Alternatively, suction may be performed under reduced pressure under heating.
[0041]
In this cleaning, the volume that the organic solvent is retained without flowing from the column, that is, the retained volume can be obtained.
Next, a liquid form sample is allowed to flow through the column for liquid chromatography. Typically, this sample is small and preferably is such that it does not flow out of the column. That is, since the diatomaceous earth column already holds sulfuric acid, an amount smaller than 100% of the holding volume is preferable. For example, a liquid sample of 70% of the holding volume may be flowed. Thereby, a sample will contact the diatomaceous earth treated with sulfuric acid. Accordingly, ordinary organic substances are decomposed by oxidation with sulfuric acid adhering to diatomaceous earth. On the other hand, analytes such as halogenated aromatic compounds in the sample are not decomposed by sulfuric acid.
[0042]
When the sample is soil or the like, the sample may be extracted with an organic solvent, and the extracted liquid sample may be passed through the column. When the sample is water, suspended solids (SS) called SS may be filtered with a filter made of a predetermined polymer, and the residue on the filter may be dissolved with an organic solvent.
[0043]
What is necessary is just to select suitably the organic solvent which melt | dissolves an analysis target substance and does not react with a sulfuric acid. For example, halogenated organic compounds such as dichloromethane; aromatic organic compounds such as benzene, toluene and xylene; alkanes such as n-hexane are preferable, and halogenated organic compounds such as dichloromethane are more preferable. This is because with aromatic organic compounds such as benzene, toluene, and xylene, when the sample is brought into contact with the sulfuric acid-treated diatomaceous earth column for a long period of time, such as one day or longer, some reaction proceeds and the column may turn black. However, when contact is made at room temperature for about 1 hour, such a reaction does not proceed remarkably, and there is no particular problem.
[0044]
And it is preferable to leave the diatomaceous earth carrying the sample for a short period of time. For example, it is preferably left for 1 minute to 24 hours, more preferably left for 2 minutes to 2 hours, further preferably left for 3 minutes to 1 hour, and still more preferably left for 3 to 30 minutes. . While left standing, impurities in the sample are oxidized and decomposed with sulfuric acid. Liquid-liquid partitioning also appears to proceed between sulfuric acid and organic solvents.
[0045]
Next, an organic solvent is passed through the column for liquid chromatography. Liquid-liquid partitioning occurs between the sulfuric acid retained in the diatomaceous earth and the flowing organic solvent, and the analyte and organic matter contained in the sulfuric acid phase are transferred to the organic solvent phase. The organic matter and the like decomposed with sulfuric acid may remain in the sulfuric acid phase or may move to the organic solvent phase.
[0046]
The organic solvent is preferably one or more times the retention volume of diatomaceous earth, and more preferably two or more times. This is because the liquid-liquid distribution is sufficiently performed and the analysis object is reliably recovered.
[0047]
What is necessary is just to select suitably the organic solvent which dissolves a to-be-analyzed object. For example, when a halogenated aromatic organic compound is an analysis object, a chlorinated organic compound such as dichloromethylene or chloroform is preferably used.
[0048]
In these series of operations, that is, a step of flowing sulfuric acid, a step of flowing a sample, a step of leaving, and a step of flowing an organic solvent, the temperature is preferably 0 ° C. to 150 ° C., more preferably 10 ° C. to 40 ° C. 15 to 30 ° C. is still more preferable, and room temperature is particularly preferable. Room temperature refers to 15 to 25 ° C, and refers to about 20 ° C. In the step of leaving, for example, the diatomaceous earth column may be heated to 150 ° C. or lower, for example, 50 to 70 ° C. by a ribbon heater or the like. Heating promotes the decomposition of impurities.
[0049]
It is preferable that the liquid flowing out from the column is concentrated appropriately by removing the solvent with an evaporator or the like under atmospheric pressure or reduced pressure, at room temperature or under heating.
The extract thus concentrated may be used for subsequent analysis. Alternatively, this extract may be further purified. For example, it is preferable to perform chromatography using an inorganic oxide as a stationary phase on a liquid that has passed through diatomaceous earth treated with sulfuric acid. The concentrated extract contains organic substances decomposed with sulfuric acid. Such an organic substance can be removed by holding it in an inorganic oxide.
[0050]
In this case, the concentrated extract may be subjected to chromatography using the inorganic oxide as a stationary phase again. Alternatively, this column may be treated with sulfuric acid as described above using a column filled with an inorganic oxide in the lower layer and filled with diatomaceous earth in the upper layer. In this column, the sample that has passed through diatomaceous earth also passes through the inorganic oxide. In this case, the inorganic oxide layer may be formed of two or more layers.
[0051]
Examples of the inorganic oxide include silica gel and alumina. Conventionally used silica gel and alumina can be used as they are. The type and amount of the filler or solvent used in column chromatography are preferably determined by conducting a fractionation test on a standard substance or the like.
[0052]
As silica gel, for example, silica gel for column chromatography (0.063-0.200mm, 70-230mesh) is washed with methanol, put into a beaker, dried at 130 ° C for about 18 hours with a layer thickness of 10mm or less, and then in a desiccator. The product may be allowed to cool for about 30 minutes. After preparation, it is preferable to store in a sealable reagent bottle and store in a desiccator.
[0053]
Multi-layer silica gel column chromatography is, for example, packed in a column chromatograph tube having an inner diameter of 15 mm and a length of 300 mm with silica gel, 2% potassium hydroxide / silica gel, 0.9 g of silica gel, 3 g of 10% silver nitrate / silica gel, and 6 g of anhydrous sodium sulfate. Things can be used. If desired, this upper stage is filled with diatomaceous earth as described above. For example, after washing the column packing with n-hexane and placing the receiver at the lower end of the column, the sample concentrate may be gently poured into the column, and the dropping outflow rate may be adjusted to 2.5 mL / min. . When the liquid level is lowered to the upper end of the column, it is preferable to wash the concentrator with 5 mL of n-hexane and put the washing solution while washing the inner wall of the column. This washing operation may be repeated once more. Next, 3 mL of n-hexane is allowed to flow into the column, and then a dropping funnel containing 120 mL of n-hexane is attached to the chromatograph tube so that n-hexane can flow down at a rate of 2.5 mL / min. The eluate may be concentrated and used as a sample for alumina column chromatography. If the filling portion is severely colored, the same operation is repeated.
[0054]
Alternatively, 3 g of silica gel is wet-packed with n-hexane in a column chromatograph tube with an inner diameter of 10 mm and a length of 300 mm, transferred to an about 10 mm layer of anhydrous sodium sulfate, and eluted with 150 mL of n-hexane. Also good. The eluate may be concentrated to about 5 mL with a concentrator and used as a sample for alumina column chromatography.
[0055]
Alumina column chromatography may be performed, for example, as follows.
A column chromatograph tube with an inner diameter of 10 mm and a length of 300 mm is wet-packed with 10-14 g of alumina (basic, activity 1) with n-hexane, overlaid with about 10 mm of anhydrous sodium sulfate, and obtained by cleaning up. The sample may be transferred and washed with a small amount of hexane. The first fraction may be obtained by flowing 100 mL of n-hexane containing 2% dichloromethane. Further, 150 mL of n-hexane + dichloromethane (1 + 1) may be passed to obtain the second fraction.
[0056]
The GC / MS analysis sample may be prepared by concentrating the second fraction to about 5 mL with a concentrator, concentrating to a small amount with a nitrogen stream, and adding an organic solvent such as n-decane or toluene to 50 to 100 μL.
[0057]
The diatomaceous earth column may be appropriately regenerated by washing with an aqueous solution of a weak base such as an aqueous sodium hydrogen carbonate solution to remove sulfuric acid.
In the second aspect of the present invention, a sample and sulfuric acid are mixed to obtain a liquid mixture. The sample may be liquid or solid. For example, the sample may be soil or fly ash. Since the contact efficiency between the sample and sulfuric acid is good, impurities in the sample can be decomposed and removed.
[0058]
However, the sample is preferably a liquid. When the sample is a solid such as soil, it is preferable to extract the analysis object into a liquid in advance. This is because the required amount of sulfuric acid increases in solids such as soil.
[0059]
The liquid mixture is then passed through a liquid chromatography column packed with diatomaceous earth. Thereby, sulfuric acid is selectively held in diatomaceous earth. Conventionally, sulfuric acid and the extract were distributed by liquid-liquid distribution using a separatory funnel. Therefore, it took time and effort. In addition, skill is required for work because sulfuric acid is handled. On the other hand, the sulfuric acid and the extract can be distributed only by flowing the liquid mixture through the diatomaceous earth column. Therefore, the work is simplified, the work time is shortened, and the safety of the worker is improved.
[0060]
It is preferable to flow a liquid mixture having a volume of 50 to 100% of the holding volume in which diatomaceous earth can hold water or the like, and it is more preferable to flow a liquid mixture having a volume of 60 to 95% to the column, It is still more preferred that a liquid mixture with a volume of 70-95% is passed through the column, and it is particularly preferred that a liquid mixture with a volume of 80-95% is passed through the column. This is because when a liquid mixture having a volume larger than 100% of the holding volume is allowed to flow through the column, the excess liquid mixture flows out of the column, and the liquid mixture needs to be neutralized and discarded. On the other hand, when a liquid mixture having a volume smaller than 50% of the holding volume is passed through the column, the efficiency is lowered.
[0061]
Similarly to the first aspect of the present invention, a column in which an inorganic oxide is filled in a lower layer and diatomaceous earth is filled in an upper layer may be used. The inorganic oxide layer may be further formed of two or more layers. The same applies to silica gel chromatography and alumina chromatography.
[0062]
In another aspect of the present invention, there is provided an analysis method in which the sample pretreated by the above method is further analyzed by GC / MS or GC / MS / MS.
The GC / MS apparatus includes, for example, a gas chromatography unit having a gas chromatography column; an ion source unit that ionizes effluent gas flowing out from the gas chromatography column; a mass analysis unit; and an ion that detects ions And a detection unit.
[0063]
As the GC / MS / MS method and apparatus, any of a triple stage quadrapole mass spectrometer, an ion trap mass spectrometer, and an ion cyclotron mass spectrometer may be used. A triple stage quadrapole mass spectrometer combines two or more quadrupole mass spectrometers. On the other hand, an ion trap mass spectrometer and an ion cyclotron type mass spectrometer can be used for tandem mass spectrometry depending on the ion scanning method. However, an ion trap mass spectrometer is preferable for analyzing halogenated aromatic compounds easily and quickly.
[0064]
The GC / MS / MS method using an ion trap mass spectrometer includes, for example, a gas chromatography step in which a sample and a carrier gas are injected into a gas chromatography column, and an outflow gas flowing out of the gas chromatography column. A precursor ion generating step of ionizing to generate a precursor ion; a trapping step of capturing the precursor ion in a trap chamber; and generating a product ion resulting from the precursor ion in the trap chamber And a product ion generating step.
[0065]
The GC / MS / MS apparatus includes, for example, a gas chromatography unit having a gas chromatography column; an ion source unit that generates precursor ions from the effluent gas flowing out from the gas chromatography column; A mass analyzer for generating product ions; and an ion detector for detecting ions.
[0066]
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. However, the present invention is not limited to the following embodiments.
FIG. 1 is an explanatory sectional view of one embodiment of a GC / MS / MS apparatus using an ion trap mass spectrometer. This apparatus includes a gas chromatography unit 10, an ion source unit 20 that generates precursor ions, a mass analysis unit 30 that separates and analyzes precursor ions, and an ion detection unit 40 that detects ions. In particular, the mass analyzer 30 has a structure unique to the ion trap mass spectrometer. In other words, the sample is separated by the gas chromatography unit 10, and each component separated by the gas chromatography unit 10 is ionized by the ion source unit 20 to generate precursor ions. It is trapped in the trap chamber of the analysis unit 30 and then dissociated in the trap chamber to generate product ions. In the ion detector 40, product ions are detected by an electron multiplier. The data can be processed by an arithmetic device (not shown) to obtain a mass spectrum of product ions and a mass chromatogram of product ions.
[0067]
In FIG. 1, a gas chromatography unit 10 includes a syringe 12 for injecting a sample, an inlet 14 for vaporizing the injected sample, particularly a liquid sample, and a column 16 connected to the inlet 14. Have The inlet 14 may be temperature controlled in consideration of the boiling point of the analysis object and the solvent. The column 16 is appropriately selected depending on the physical properties and chemical properties of the analyte, the solvent in the sample, and the like. For example, a column using a silicone resin as a filler can be used. For example, a column having polysiloxane containing an arylene group in the main chain as a stationary phase may be used. The carrier gas is generally introduced into the inlet 14 and then the column 16 of the gas chromatography unit 10 from a port (not shown).
[0068]
The column 16 is preferably a capillary column. The inner diameter of the capillary column is preferably 0.05 to 3 mm, more preferably 0.1 to 1 mm. The length of the capillary column is preferably 1 to 300 m, and more preferably 10 to 100 m.
[0069]
As for the column 16, it is preferable that a gas chromatography column is packed with a polysiloxane containing an arylene group in the skeleton.
The analysis object, matrix, and solvent in the sample are separated by the gas chromatography unit 10, and each component is introduced into the ion source unit 20. In FIG. 1, ionization of the analysis object or the like is performed upstream of the mass analysis unit 30. However, ionization of the analysis object may be performed inside the trap chamber of the mass spectrometer.
[0070]
The ion source unit 20 is vacuum (for example, 2 × 10^-FiveAnd a vacuum chamber 22 connected to the outlet of the column 16 of the gas chromatography unit 10 and an ionizer 24 for ionizing molecules. The ionization part 24 contains a filament, for example.
[0071]
The method of ionizing molecules by the ion source unit 20 is not limited, such as electron ionization (EI), chemical ionization (CI), and fast atom bombardment (FAB).
[0072]
In the case of fast atom bombardment or the like, it is preferable to use a gas having a small molecular weight. For example, an inert gas such as helium, a lower hydrocarbon such as methane or isobutane; a nitrogen-containing compound such as ammonia or acetonitrile can be used as the ionization gas. When a halogenated aromatic organic compound is used as an analysis target, an inert gas such as helium is preferably used. For example, tetrachlorodibenzo-p-dioxin has various isomers depending on the substitution position of the chlorine atom. And in inert gas, such as helium, it is preferable that different isomers ionize to the same extent.
[0073]
For example, when the GC carrier gas is helium, helium can also be introduced into the ionization chamber along with the analyte and matrix to ionize the analyte.
[0074]
In the case where the lower hydrocarbon, nitrogen-containing compound or the like is an ionized gas, an ionized gas and a carrier gas such as helium may be introduced into the GC. For example, the flow rate of the ionized gas is preferably larger than the flow rate of a carrier gas such as helium.
[0075]
The ion source unit 20 is connected to the mass analysis unit 30 by a passage 26. Precursor ions generated by the ion source unit 20 can be introduced into the mass analysis unit 30.
Here, the passage 26 is preferably provided with lenses 28a, 28b, and 28c. Lenses 28a, 28b, 28c accelerate or decelerate precursor ions as desired. Further, the lenses 28a, 28b, and 28c can efficiently guide the precursor ions into the trap by converging the precursor ions. This makes it difficult for the precursor ions to adhere to the inner wall of the passage 26.
[0076]
FIG. 2 shows the mass spectrometer 30. The mass spectrometer 30 includes a ring electrode 32 having a ring shape and a pair of end caps 33 and 34 disposed in a pair of openings of the ring electrode 32. A space surrounded by the ring electrode 32 and the pair of end caps is a trap chamber 37.
[0077]
The ring electrode 32 is connected to a trap voltage generator 35, and typically, an RF voltage can be applied between the ring electrode 32 and the end caps 33 and 34. For example, V₁sinωt (where V₁Is a voltage, and ω is a time t). As a result, the trap chamber 37 has a radius r0 and a vertical dimension z.₀And z₀ ²= R₀ ²A quadrupole electric field that traps ions in a space having a relationship of / 2 is generated.
[0078]
The end cap 34 is connected to a dissociation voltage generator 36. The dissociation voltage is typically, for example, V₂sinωt (where V₂Is a voltage, and ω is a time t). Precursor ions trapped in the trap chamber 37 can resonate at their principal axis resonance frequency and dissociate to generate product ions.
[0079]
Each parameter of the ion trap mass spectrometer is described in, for example, “GC Stanford et al., Int. J. Mass Spectrom. Ion Processes, 60, 88 (1984)”.
[0080]
The end cap 34 is connected to an ion detector 40, in particular, an electron multiplier that is a main part of the ion detector 40, through an ion passage hole. Ions destabilized in the ion trap electric field are detected by an electron multiplier. Thereby, a mass spectrum and a mass chromatogram of ions discharged from the trap chamber 37 can be obtained.
[0081]
In the embodiment of FIG. 1, product ions are generated by an ion source unit 20 that is separate from the mass analysis unit 30. However, ionization may be performed within the electric field of the ring electrode 32 of the mass spectrometer 30.
[0082]
FIG. 3 shows the operation of the trap voltage generator 35 and the dissociation voltage generator 36. Initially, both the trap voltage and the auxiliary voltage are zero. Then time t₁Then, a trap voltage is applied by the trap voltage generator 35 and the precursor ions are trapped in the trap chamber 37. Thereby, the RF voltage of the ring electrode rises as indicated by reference numeral 52 in FIG.
[0083]
Then time t₂Then, an auxiliary voltage is applied by the auxiliary voltage generator 36 to dissociate precursor ions and generate product ions. As a result, the RF voltage of the ring electrode 32 decreases, for example, as indicated by reference numeral 54 in FIG.
[0084]
For example, the trap chamber 37 captures not only precursor ions but also ions originating from the carrier gas used in gas chromatography. The carrier gas ions may act as collision ions that collide with the precursor ions. That is, the precursor ions and the collision ions may resonate with each other by the auxiliary voltage, collide with each other, and the precursor ions may dissociate to generate product ions.
[0085]
The period during which the auxiliary voltage is applied, that is, the time t₂And t_ThreeProduct ions may continue to be trapped in the trap chamber 37. Alternatively, product ions may be emitted from the trap chamber 37 and detected by the ion detector 40.
[0086]
Next, as indicated by reference numeral 56 in FIG. 3, the RF voltage of the ring electrode 32 is swept to discharge ions (precursor ions and product ions) remaining in the trap chamber 37 from the trap chamber 37. And may be detected by the ion detector 40.
[0087]
FIG. 4 shows a mass chromatogram of product ions obtained by the GC / MS / MS method using an ion trap mass spectrometer. In the mass chromatogram, the x-axis represents time, and the y-axis represents a numerical value obtained by calculating the intensity or intensity of a predetermined ion mass of the mass spectrum. On the y-axis, the intensity of one specific ion mass may be indicated, the sum of the intensity of two specific ion masses may be indicated, or the sum of the intensity of three specific ion masses may be indicated. Also good.
[0088]
FIG. 5 shows that 500 fg, ie 0.5 pg of 2,3,7,8-tetrachlorodibenzo-p-dioxin and 100 pg of¹³The mass chromatogram when applying the GC / MS / MS method using an ion trap mass spectrometer is shown about the sample containing C-2,3,7,8-tetrachloro dibenzofuran. In FIG. 5, the sum of the intensity of product ions with ion masses of 257, 258 and 259 is shown on the y-axis. In FIG. 5, when the number of scans is about 155 times,¹³A chromatographic peak 61 of C-2,3,7,8-tetrachlorodibenzofuran is observed, and a chromatographic peak 62 of 2,3,7,8-tetrachlorodibenzo-p-dioxin is observed after about 180 scans. ing. Regarding the number of scans, gases discharged from gas chromatography in a certain period are collected and MS / MS is measured once. This one measurement is also called a scan. The number of scans of about 155 is a time that is 155 times the fixed period.
[0089]
FIG. 6 is a mass spectrum showing the ion mass distribution of the product ion 2,3,7,8-tetrachlorodibenzo-p-dioxin corresponding to the chromatographic peak 61 of FIG. FIG. 7 is a product ion showing an ion mass distribution corresponding to the chromatographic peak 62 of FIG.¹³It is a mass spectrum of C-2,3,7,8-tetrachlorodibenzofuran. 6 and 7 are observation data of the ion mass distribution of the product ions, which are almost equal to the theoretical value of the ion mass distribution of the product ions.
[0090]
As described above, the observation data of the ion mass distribution of the product ions, for example, the observation data of the ion mass distribution in which the ion masses are distributed in 257, 258, and 259 can identify and identify the approximate substance. .
[0091]
In FIG. 5, the chromatopeak of 2,3,7,8-tetrachlorodibenzo-p-dioxin,¹³The chromatographic peak of C-2,3,7,8-tetrachlorodibenzofuran can be clearly distinguished.
[0092]
When comparing the observation data of the ion mass distribution of product ions with the theoretical value of the ion mass distribution of product ions, for example, compare the observed ion mass distribution itself with the theoretical value of the ion mass distribution with the human eye. Thus, the chromatographic peak in the mass chromatogram may be identified. For example, FIG. 6 and FIG. 7 show observation data of ion mass distribution of product ions, respectively. This observation data is within the range of error in drawing creation and is consistent with the theoretical value of ion mass distribution. I'm doing it.
[0093]
Alternatively, the intensity ratio of the ion mass may be calculated from the observation data, or the intensity ratio of the ion mass may be calculated from the theoretical value, and both intensity ratios may be compared. For example, the ion mass distribution has, for example, three consecutive peaks, and two ratios are taken for any two peaks from the three peaks, and the two ratios are compared with a theoretical value. For example, in the case of 2,3,7,8-tetrachlorodibenzo-p-dioxin, the ratio of the peak of ion mass 257 to the peak of ion mass 258 and the peak mass of ion mass 257 and the ion mass are It is also possible to calculate ratios with the peak of 259 and compare these ratios with theoretical values.
[0094]
In one embodiment of the present invention, precursor ions generated by electron ionization (EI) or the like are selectively trapped in the ring electrode, the precursor ions are dissociated, and a new mass-to-charge ratio m / z is obtained. Product ions are generated. For example, neutral atoms (He) are collided to dissociate precursor ions (CAD; Collisionally Activated Dissociation). By selecting the m / z of the precursor ion and the product ion, it becomes possible to specifically detect the analyte such as dioxins.
[0095]
【Example】
Examples of the present invention will be described below, but the present invention is not limited to the following examples.
[0096]
Tandem mass spectrometry was performed using an ion trap mass spectrometer GCQ plus manufactured by Thermoquest. The ionization current was 500 μA, the ion source temperature was 270 ° C., the acceleration voltage was 8 kV, and the electron acceleration voltage was 40 to 70 eV.
[0097]
The GC conditions are as follows. For soil samples, as an internal standard,¹³2,3,7,8-Tetrachlorodibenzo-p-dioxin (TeCDD) and 2,3,7,8-tetrachlorodibenzofuran (TeCDF), labeled with C, were added.
[0098]
The syringe, without splitting, injected a 1 μl volume of sample, ie, a toluene solution, into the GC apparatus at 250 ° C.
Helium was used as the carrier gas, and the flow rate and linear velocity were 30 cm / min.
[0099]
The oven is heated at 100 ° C. for 1 minute, then heated at 30 ° C./minute, held at 250 ° C. for 12 minutes, further heated at 5 ° C./minute to 310 ° C. or the separation temperature shown in Table 2. Retained.
[0100]
As the column, Meridian column, MDN-12, sold by Supelco Japan, was used. This column had an inner diameter of 0.25 mm, a length of 60 m, and a film thickness of 0.2 μm.
[0101]
MDN-12 is a polysiloxane represented by the following formula (I), and R¹, R², R^Three, R^Four, R^FiveAnd R⁶Is 88 mol% of methyl group, R¹, R², R^Three, R^Four, R^FiveAnd R⁶In which 12 mol% of the bisphenol is a phenyl group.
[0102]
[Chemical 1]

[0103]
These gas chromatographic conditions are set so that the 10 parent ions of dioxins (4-8 chlorinated dioxins and 4-8 chlorinated dibenzofurans) are completely separated and introduced into the mass spectrometer. Yes.
Comparative Example 1
A commercially available disc filter was used as the styrene divinylbenzene filter. The filter was held in a Kiriyama funnel or similar instrument and a receptacle was placed underneath. The sample is loaded, and liquid is passed by making the receiver side negative pressure. After passing through the solution, a small amount of acetone was passed through a disk filter to elute dioxins.
[0104]
Soil samples collected from around the incinerator were extracted with organic substances in the soil with toluene using a high-temperature, high-pressure solvent extraction device ASE-200 (manufactured by Dionex). In order to remove the water remaining in the sample, an amount of anhydrous sodium sulfate equivalent to the sample was uniformly mixed. Dioxins were extracted by raising the pressure to 120 atm or higher and the temperature to 120 ° C or higher. In order to improve the extraction efficiency, extraction was performed twice. The obtained organic substance was concentrated to about 1 ml with an evaporator to obtain a toluene extract of dioxins.
[0105]
This toluene extract was subjected to GC / MS / MS analysis. An analysis interfering substance was detected, and GC / MS / MS analysis was not possible.
Example 1
A commercially available disc filter was used as the styrene divinylbenzene filter. The filter was held in a Kiriyama funnel or similar instrument and a receptacle was placed underneath. The sample is loaded, and liquid is passed by making the receiver side negative pressure. After passing through the solution, a small amount of acetone was passed through a disk filter to elute dioxins.
[0106]
Soil samples collected from around the incinerator were extracted with organic substances in the soil with toluene using a high-temperature, high-pressure solvent extraction device ASE-200 (manufactured by Dionex). In order to remove the water remaining in the sample, an amount of anhydrous sodium sulfate equivalent to the sample was uniformly mixed. Dioxins were extracted by raising the pressure to 120 atm or higher and the temperature to 120 ° C or higher. In order to improve the extraction efficiency, extraction was performed twice. The obtained organic substance was concentrated with an evaporator to obtain a toluene extract of dioxins.
[0107]
On the other hand, 98% sulfuric acid having a volume of about 80% of the retained volume of diatomaceous earth in a diatomaceous earth column commercially available as Extube from Varian was flowed and left for 30 minutes to treat the surface of diatomaceous earth with sulfuric acid. Next, the toluene extract was added to the diatomaceous earth column treated with sulfuric acid and allowed to stand for 10 minutes. Dioxins were eluted with dichloromethane and then passed through a silica gel column. Subsequently, it concentrated by the evaporator and the dichloromethane extract was obtained. This dichloromethane extract was added to a silica gel column and eluted with toluene. Subsequently, it concentrated by the evaporator and the toluene solution was obtained. This toluene solution was subjected to GC / MS / MS analysis.
[0108]
Even when the toluene solution was concentrated to 200 μl, the analysis was possible without being disturbed by the interfering substances. Compared with Comparative Example 1, the concentration rate was 5 times, and analysis was possible up to lower sensitivity.
Example 2
The recovery rate of dioxins in the sample was calculated for the fly ash discharged from the incinerator. Note that fly ash has less matrix than soil.
[0109]
About fly ash, it processed similarly to the comparative example 1, and investigated the quantity of dioxins. On the other hand, fly ash was treated in the same manner as in Example 1 to examine the amount of dioxins. That is, the method of Comparative Example 1 is not treated with either a sulfuric acid-treated diatomaceous earth column or a silica gel column, whereas the method of Example 1 is different in that it is treated with a sulfuric acid-treated diatomaceous earth column or a silica gel column. .
[0110]
Based on the case where the sulfuric acid-treated diatomite column and silica gel column were not treated, the recovery rate of dioxins when the sulfuric acid-treated diatomaceous earth column and silica gel column were treated was determined. The average recovery of 2,3,7,8-tetrachloropolychlorodibenzo-p-dioxin (T4CDD) is 97%, 1,2,3,7,8-pentachloropolychlorodibenzo-p-dioxin (P5CDD) ) Recovery rate of 110%, hexachloropolychlorodibenzo-p-dioxins (H6CDDs) average recovery rate of 87%, 1,2,3,4,6,7,8-heptachloropolychlorodibenzo -The average recovery rate of p-dioxin (H7CDD) is 87%, and the average recovery rate of 1,2,3,4,5,6,7,8-octachloropolychlorodibenzo-p-dioxin (O8CDD) is 94%.
[0111]
This result shows that the recovery rate of the pretreatment method of the present invention is high and is effective in improving sensitivity.
In the following Examples 3 to 5, the sample pretreated in Example 1 was analyzed by GC / MS / MS using an ion trap mass spectrometer.
Example 3
Soil was collected from a certain incineration site in Japan, and then the soil treated with an alkali catalyst to reduce the concentration of dioxins was used as a sample. Polychloro DD and polychloro DF were quantified with respect to the soil near the lower limit of quantification.
[0112]
The results are shown in Table 1.
[0113]
[Table 1]

[0114]
In the table, CDD means chlorodibenzo-p-dioxin, and CDF means chlorodibenzofuran. T4, P5, H6, H7, and O8 mean tetra, penta, hexa, hepta, and octa, respectively. The same applies hereinafter.
[0115]
The quantitative values of the conventional method and the method of the present invention agreed very well. In the method of the present invention, it was possible to quantify up to 1 pg / g for each isomer. As a result, it became possible to quantify soil samples of about 10 pg-TEQ / g.
[0116]
The TEQ is as follows. In one sample, various isomers of polychlorodibenzo-p-dioxins are usually present. And each isomer has its toxicity different. Therefore, a value obtained by converting the total amount of toxicity of various isomers in the sample into the toxicity of 2,3,7,8-TeCDD is referred to as TEQ. A TEQ of 8.0 ng-TEQ / g means that polychlorodibenzo-p-dioxins in an amount equivalent to 8.0 ng of 2,3,7,8-TeCDD contained in a 1 g sample. Or polychlorodibenzofurans are included.
Example 4
Soil containing high concentrations of dioxins was collected from the site of a foreign chemical factory. Polychlorinated DD and polychlorinated DF were quantified with respect to this highly contaminated soil. The experimental results are shown in Table 2.
[0117]
The quantification by the conventional method was performed by two independent analytical institutions A and B. As can be seen from Table 2, the quantitative values of the conventional method and the method of the present invention agreed very well even for the high concentration sample. In the method of the present invention, it was possible to quantify a soil sample of about 10 ng-TEQ / g.
[0118]
[Table 2]

[0119]
Example 5
The mass chromatogram of the internal standard substance is shown in FIG. 2,3,7,8-tetrachloropolychlorodibenzo-p-dioxin (T4CDD), 1,2,3,7,8-pentachloropolychlorodibenzo-p-dioxin (P5CDD), hexachloropolychlorodibenzo -P-dioxins (H6CDDs), 1,2,3,4,6,7,8-heptachloropolychlorodibenzo-p-dioxin (H7CDD), 1,2,3,4,5,6,7, It is a chromatogram about the mixture of 8-octachloropolychlorodibenzo-p-dioxin (O8CDD). The injection amount of each polychlorodibenzo-p-dioxin was 30 pg.
[0120]
Hexachloro DDs have a slight baseline disturbance but do not affect the quantification. The other peaks are not affected by impurities. This suggests that the method of the present invention is sufficiently selective for dioxins in the soil sample.
[0121]
【The invention's effect】
By using a diatomaceous earth column, it became possible to coat diatomaceous earth with sulfuric acid by natural dripping. As a result, the number of analysis work steps is reduced, and the work time and thus the analysis time is shortened.
[0122]
Furthermore, safety was improved because the worker only contacted the sulfuric acid when loading the column with sulfuric acid.
[Brief description of the drawings]
FIG. 1 is an explanatory sectional view of one embodiment of a GC / MS / MS apparatus using an ion trap mass spectrometer.
FIG. 2 is an explanatory cross-sectional view of a mass spectrometer of the apparatus of FIG.
FIG. 3 is an explanatory diagram showing voltage control of a mass spectrometer.
FIG. 4 is a mass chromatogram of an internal standard substance.
FIG. 5 shows a mass chromatogram obtained in one embodiment of the present invention.
FIG. 6 is a mass spectrum showing an ion mass distribution of product ions corresponding to one chromatographic peak.
FIG. 7 is a mass spectrum of product ions showing ion mass distributions corresponding to distinct chromatographic peaks.
FIG. 8 shows a flow sheet for pretreatment of conventional GC / MS.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Gas chromatography part, 12 ... Syringe, 14 ... Oven, 16 ... Column, 18 ... Outlet, 20 ... Ion source part, 22 ... Vacuum chamber, 24 ... Ionizer, 26 ... Passage, 28a, 28b, 28c ... Lens , 30 ... Mass analyzer, 32 ... Ring electrode, 33 ... End cap, 34 ... End cap, 35 ... Trap voltage generator, 36 ... Dissociation voltage generator, 37 ... Trap chamber, 40 ... Ion detector

Claims (6)

Flow sulfuric acid through a column for liquid chromatography packed with diatomaceous earth, treat the diatomaceous earth with sulfuric acid,
A sample pretreatment method, wherein a liquid form sample is allowed to flow through the liquid chromatography column. The pretreatment method according to claim 1, wherein the liquid that has passed through the diatomaceous earth treated with sulfuric acid is subjected to chromatography using an inorganic oxide as a stationary phase. Mixing the sample and sulfuric acid to obtain a liquid mixture;
Flowing the liquid mixture through a liquid chromatography column filled with diatomaceous earth;
A sample pretreatment method comprising: The sample pretreatment method according to claim 1, wherein the sample contains a halogenated aromatic organic compound. The analysis method which analyzes further the sample pre-processed by the method in any one of Claims 1-4 by GC / MS. The analysis method which analyzes the sample pre-processed by the method in any one of Claims 1-4 further by GC / MS / MS.

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