JP5208371B2 - Determination of polychlorinated biphenyls - Google Patents

Description

The present invention relates to a method for quantifying polychlorinated biphenyls, and more particularly to a method for quantifying polychlorinated biphenyls contained in a hydrophobic sample.

Polychlorinated biphenyls [hereinafter sometimes abbreviated as PCBs] contained in hydrophobic samples such as insulating oil used in transformers and the like. ], It is necessary to remove in advance the coexisting substances that interfere with the quantification of PCBs. However, such coexisting substances cannot be separated by ordinary processing methods such as column chromatography. Some are difficult. For this reason,
Non-Patent Document 1 [Attached Table 2 of Special Notification General Waste and Special Management Industrial Waste on July 3, 1992, revised by the Ministry of Health, Labor and Welfare Notification No. 633, December 28, 2000 According to the so-called official method described in “Testing method of such standards”], after repeating the operation of treating a hydrophobic sample with concentrated sulfuric acid in liquid-liquid contact, the coexisting substances are treated by the above column chromatographic treatment or the like. A method of removing by a method is disclosed, and a method of treating a hydrophobic sample using fuming sulfuric acid having a free SO ₃ concentration of 25% by mass in place of concentrated sulfuric acid is also known. Hydrophobic samples after liquid-liquid contact with concentrated sulfuric acid or fuming sulfuric acid are separated from concentrated sulfuric acid or fuming sulfuric acid by a liquid separation operation, and this method of treatment removes difficult-to-separate interfering substances contained in hydrophobic samples. can do.

However, it is troublesome to repeat the operation of separating the hydrophobic sample after the liquid-liquid contact from concentrated sulfuric acid or fuming sulfuric acid.

On the other hand, as a method for easily removing an interfering substance in a relatively short time, there is known a method in which a hydrophobic sample is contacted with concentrated sulfuric acid-impregnated diatomaceous earth obtained by impregnating a porous carrier made of diatomaceous earth with concentrated sulfuric acid alone. In Patent Document 1 (Japanese Patent Laid-Open No. 2001-116723, page 9, paragraph number 0082), a hydrophobic sample is passed through a column packed with this concentrated sulfuric acid-impregnated diatomaceous earth, and then silica gel column chromatography is used. Interfering substances are removed by performing graph processing.

However, the conventional decomposition method using concentrated sulfuric acid alone has a problem that it is not possible to sufficiently remove interfering substances that are difficult to separate from PCBs.

December 28, 2000, Ministry of Health, Labor and Welfare Notification No. 633, revised on July 3, 1992, Ministry of Health, Labor and Welfare Notification No. 192, Approval Method for Standards Related to Special Management General Waste and Special Management Industrial Waste " Paragraph No. 0082 on page 9 of JP 2001-116723 A

Therefore, the present inventors have intensively studied to develop a method capable of quantifying PCBs by sufficiently removing coexisting substances contained in a hydrophobic sample and interfering with the quantification of PCBs by a simple operation. As a result, the present invention has been achieved.

That is, the present invention includes a step of bringing the hydrophobic sample into contact with fuming sulfuric acid-impregnated silica gel satisfying the following conditions as a pretreatment step in quantifying PCBs in a hydrophobic sample containing PCBs. A method for quantifying the PCBs is provided.

Oleum impregnated silica gel: BET specific surface area of 250m ² / g~450m ² / g, the silica gel pore volume 1.4cm ³ /g~2.6cm ³ / g, free SO ₃ concentration of 5% to 40% by weight Fumed sulfuric acid impregnated silica gel impregnated with fuming sulfuric acid

According to the method of the present invention, fuming sulfuric acid having a free SO ₃ concentration of 5 to 40% by mass is impregnated into the specific silica gel specified in the present invention, so that the interfering substances contained in the hydrophobic sample are sufficiently removed. It becomes possible.

The hydrophobic sample applied to the method of the present invention is a hydrophobic liquid sample, for example, trans,
Examples thereof include an oily sample such as an insulating oil used by being enclosed in an electric device such as a condenser for insulation or cooling, or a decomposition-treated oil obtained by decomposing the insulating oil. Such an oily sample may be used as it is without being diluted, or may be used after being diluted with a hydrophobic solvent such as n-hexane or cyclohexane.

Examples of hydrophobic samples include solid samples such as soot discharged from incinerators, burning husks, soil samples collected from soil, water samples such as rainwater and drainage, n-hexane, toluene and the like. A hydrophobic solution containing PCBs extracted with a hydrophobic solvent is also mentioned.

In order to extract PCBs from a solid sample or a water quality sample with a hydrophobic solvent, for example, the solid sample or the water quality sample may be brought into contact with the hydrophobic solvent as described above.

The hydrophobic solvent extract obtained by extracting PCBs from a solid sample or a water quality sample with a hydrophobic solvent may be used as it is as a hydrophobic sample, but usually other coexistence extracted with PCBs. In order to separate the substances, PCBs are further extracted with a polar organic solvent from a hydrophobic solvent extract such as n-hexane or toluene, and the obtained polar organic solvent extract is subjected to PC.
B is dissolved in a hydrophobic solvent. Examples of such a polar organic solvent include dimethyl sulfoxide, acetonitrile, methanol, n-methylpyrrolidone and the like. In order to dissolve the polar organic solvent extract into the hydrophobic solvent, for example, water may be added to the polar organic solvent extract and then extracted with the hydrophobic solvent.

The fuming sulfuric acid-impregnated silica gel used in the method of the present invention is obtained by impregnating silica gel with fuming sulfuric acid.

The silica gel, BET specific surface area of 250m ² / g~450m ² / g, preferably from 250m ² / g~350m ² / g. A pore volume of 1.4cm ³ /g~2.6cm ³ / g, preferably is used as the 1.6cm ³ /g~2.6cm ³ / g.

Fuming sulfuric acid is obtained by absorbing sulfur trioxide [SO ₃ ] gas in concentrated sulfuric acid, and its free SO ₃
The concentration is measured according to JIS K8741. Generally, the free SO ₃ concentration of fuming sulfuric acid that is commercially available is 10% by mass to 60% by mass. Therefore, the fuming sulfuric acid having the free SO ₃ concentration defined in the present invention is, for example, commercially available fuming sulfuric acid, concentrated sulfuric acid, ie, H It can be prepared by a method of diluting by adding sulfuric acid having a concentration of ₂ SO _{4 of} 98% by mass or more, a method of injecting sulfur trioxide gas into a commercially available fuming sulfuric acid or concentrated sulfuric acid and absorbing it.

The free SO ₃ concentration of fuming sulfuric acid is 5% by mass or more, preferably 15% by mass or more in terms of sufficiently removing interfering substances, and 40% by mass or less, preferably in terms of accurately quantifying PCBs. Is 30% by mass or less.

The amount of the fuming sulfuric acid impregnated with respect to the silica gel may be an amount that can be impregnated and retained in the silica gel, and is usually 0.5 to 5 times by mass with respect to the silica gel. The amount is preferably 2.5 times by mass or less in that it hardly oozes out and the particles do not stick to each other and are easy to handle as a powdered and fluid fuming sulfuric acid silica gel.

The contact between the hydrophobic sample and the fuming sulfuric acid-impregnated silica gel is usually achieved by passing the hydrophobic sample through a fuming sulfuric acid-impregnated silica gel column packed with fuming sulfuric acid-impregnated silica gel.

In order to prepare such a fuming sulfuric acid-impregnated silica gel column, for example, the silica gel may be mixed with the above fuming sulfuric acid to form a fuming sulfuric acid-impregnated silica gel and then packed into the column. Since the silica gel having the BET specific surface area and pore volume defined in the present invention can maintain a powder state even when impregnated with a relatively large amount of fuming sulfuric acid, for example, fuming sulfuric acid exceeding 2 times by mass, it is packed in a column. Is also easy.

A fuming sulfuric acid impregnated silica gel column can also be prepared by adding the above fuming sulfuric acid after the column is filled with the silica gel.

The contact temperature when the hydrophobic sample is brought into contact with the fuming sulfuric acid-impregnated silica gel is usually about 0 ° C to 50 ° C. The contact time is usually about 1 minute to 20 minutes, preferably 3 minutes to 10 minutes because it is excellent in quantitative accuracy and can be measured efficiently.

Depending on the viscosity of the hydrophobic sample, it may be difficult to pass through the fuming sulfuric acid impregnated silica gel column as it is, but in such a case, the hydrophobic sample is appropriately selected, for example, n-hexane, heptane, cyclohexane, etc. The solution may be passed as a solution of the hydrophobic solvent, or after the hydrophobic sample is placed on the fuming sulfuric acid impregnated silica gel column, it may be passed through while being diluted by flowing the hydrophobic solvent down.

The hydrophobic solvent sample is preferably dehydrated in advance. In order to dehydrate, for example, it may be brought into contact with a desiccant. As a fuming sulfuric acid impregnated silica gel column, a column having a two-layer structure in which a desiccant is further filled on the upstream side is used. It may be configured to pass through the fuming sulfuric acid impregnated silica gel layer after being dehydrated by passing, or a desiccant column filled with a desiccant is separately connected to the upstream side of the fuming sulfuric acid impregnated silica gel column. The hydrophobic sample may pass through the desiccant column and then pass through the fuming sulfuric acid impregnated silica gel column. As the desiccant, a desiccant inert to fuming sulfuric acid and concentrated sulfuric acid such as anhydrous sodium sulfate is usually used.

Interfering substances can be removed by subjecting the hydrophobic sample after contact with the fuming sulfuric acid-impregnated silica gel, for example, to silica gel column chromatography. For silica gel column chromatography, a silica gel column in which the column is filled with silica gel is usually used, and the column is usually connected to the downstream side of the fuming sulfuric acid impregnated silica gel column.

The hydrophobic sample after performing such a treatment operation may be concentrated by a method such as evaporation of the solvent, if necessary.

In addition, after the above-described processing operation, other coexisting substances remaining in the hydrophobic sample can be removed by subjecting to a purification treatment such as a normal column chromatography method as necessary.

For example, among the above-mentioned other coexisting substances, lipophilic substances are obtained by extracting PCBs contained in a hydrophobic sample with a polar organic solvent, and using the obtained polar solvent extract as a column chromatography using a lipophilic adsorbent as a filler. By performing graph processing, it can be separated from PCBs. Examples of the polar organic solvent include those described above. The lipophilic adsorbent is a solid adsorbent composed of a material having at least a surface having affinity with an oily substance, and is usually in a granular form. Examples of such lipophilic adsorbents include those widely used as column chromatography packing materials, solid phase extraction packing materials, and column packing materials for reversed-phase liquid chromatography. Filler “C18” from Waters, USA “SEP-PAK-C18”, “SEP-PAK-tC18”
, "SEP-PAK-Vac tC18" or other commercial products can be used.

Such column chromatography is performed, for example, by allowing a polar organic solvent extract to flow down a column filled with a lipophilic adsorbent. The polar solvent extract after flowing down may be concentrated as necessary.

When the polar organic solvent extract after column chromatography with a lipophilic adsorbent contains hydrophilic substances as other coexisting substances, for example, P contained in the polar organic solvent extract
This can be removed by transferring CBs into a hydrophobic solvent. In order to dissolve PCBs contained in the polar organic solvent extract in a hydrophobic solvent, for example, water may be added to the polar organic solvent extract and then extracted with the hydrophobic solvent.

If necessary, the transferred solution thus transferred can be subjected to multilayer silica gel column chromatography to remove the remaining coexisting substances. Such multi-layer silica gel column chromatography is performed by passing the transferred solution through a multi-layer silica gel column having a multi-layer structure in which the column is filled with a silica gel filler such as untreated silica gel, potassium hydroxide-coated silica gel, or sulfuric acid-coated silica gel. Is called. The transferred solution after passing may be concentrated by a method such as solvent distillation.

The method for quantifying PCBs after the above pretreatment is not particularly limited. For example, a gas chromatograph-mass spectrometry (GC-MS method), an electron capture detector (ECD) as a detector is used. Examples thereof include a GC (ECD) method, which is a gas chromatographic method to be used, and a GPC-GC (ECD) method in which quantification is performed by a GC (ECD) method from a fraction fractionated by a gel permeation chromatograph.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by these Examples.

In addition, the BET specific surface area of the silica gel used in each Example was measured by a one-point method using a “flow type specific surface area automatic measuring device Flow Sorb 2300” manufactured by MICROMETRICS.
The pore volume was determined as a pore volume having a pore radius in the range of 0.001 μm to 100 μm using “Auto Porosimeter Autopore III 9420” manufactured by MICROMETRICS.

Example 1
[Preparation of simulated insulating oil]
A simulated insulating oil was prepared by adding PCBs to a commercially available insulating oil. The content of PCBs contained in 1 g of the simulated insulating oil is shown in Non-Patent Document 1 [Appendix Table of the Ministry of Health and Welfare Notification No. 192 revised on December 28, 2000 by Ministry of Health and Welfare Notification No. 633 It was as shown in Table 1 when it was measured in accordance with “No. 2“ Examination method for standards concerning specially managed municipal waste and specially managed industrial waste ””.

Table 1
━━━━━━━━━━━
3 Chlorine 270 ng
4-chlorine 270 ng
5 Chlorine 230 ng
6 Chlorine 140 ng
7 Chlorine 100 ng
8 Chlorine 40 ng
───────────
1050ng total
━━━━━━━━━━━

[Preparation of fuming sulfuric acid impregnated silica gel]
Silica gel having a BET specific surface area of 252 m ² / g and a pore volume of 2.58 cm ² / g was dried at 150 ° C. for 12 hours. 6 g of this silica gel is weighed with an electronic balance into a vial with a capacity of 100 mL, and 7.3 mL (13.5 g) of fuming sulfuric acid having a free SO ₃ concentration of 25% by mass (made by Wako Pure Chemical Industries, Ltd., reagent grade 1) is added. After the addition, the cap was quickly sealed and shaken for 20 minutes to thoroughly mix the contents. The contents were in the form of a fluid powder that did not stick to each other.

[Pretreatment of simulated insulating oil]
A polypropylene disposable syringe having a capacity of 10 mL was used as a column, and a glass fiber filter paper (manufactured by ADVANTEC, GA-100) was laid on the bottom thereof, and 0.5 g of silica gel (manufactured by Wako Pure Chemical Industries, Ltd., “Wakogel DX”) was used. 2 g of the prepared fuming sulfuric acid-impregnated silica gel and 0.5 g of anhydrous sodium sulfate [manufactured by Wako Pure Chemical Industries, Ltd., “for residual agricultural chemical test”] were packed in this order to prepare a fuming sulfuric acid-impregnated silica gel column.

To this column, 590 μL (corresponding to 0.5 g) of the simulated insulating oil prepared above is added from above, and 200 μL of n-hexane (manufactured by Wako Pure Chemical Industries, Ltd., “for measuring dioxins”) is added, and the mixture is allowed to stand for 5 minutes. I put it.

Next, 15 mL of n-hexane (manufactured by Wako Pure Chemical Industries, Ltd., “for dioxins measurement”) was added, and the eluate was collected from the bottom of the syringe into an eggplant flask having an internal volume of 30 mL. This eluate contains PCB. 40 μL of PCB internal standard substance (“MBP-GC Solution Mixture of ¹³ C ₁₂ -PCBs” manufactured by Wellington, Inc.) was added to this eluate, concentrated under reduced pressure using a rotary evaporator, and transferred to a separatory funnel having an internal volume of 25 mL. .

[Column Chromatograph Processing]
After adding 3.2 mL of dimethyl sulfoxide to the separatory funnel after transferring the concentrated liquid as described above, shaking for 10 minutes, allowing to stand, and liquid-separating to obtain a dimethyl sulfoxide extract three times. The extracted liquids were combined and passed through two tC ₁₈ columns [Waters, “Sep-Pak Vac tC18 3 cc”] connected in series.

After adding 12 mL of dilute hydrochloric acid [18% hydrochloric acid] obtained by diluting 36% hydrochloric acid [manufactured by Wako Pure Chemical Industries, Ltd., for residual agricultural chemical test] to 2 times volume with pure water, the total amount of the flowing-down solution was mixed, and then 6 mL of n-hexane The resulting n-hexane extract was added to a multilayer silica gel column, and then developed with 90 mL of n-hexane, and the wake was collected except for 20 mL of the initial stream. In addition, as this multilayer silica gel column, a non-treated silica gel 1 g, 2% potassium hydroxide-coated silica gel 3 g, an untreated silica gel as a filler from the downstream side by wet packing using n-hexane into a glass column having an inner diameter of 15 mm. 1 g, 10 g of 44% sulfuric acid-coated silica gel, 5 g of untreated silica gel, and 2 g of anhydrous sodium sulfate were used in this order.

The total amount of the collected effluent was concentrated to 1 mL at 30 ° C. by a rotary evaporator, and further the solvent was distilled off under a dry nitrogen stream and concentrated to 200 μL to obtain an n-hexane sample.

[Quantification of PCBs by GC-MS method]
To the n-hexane sample obtained above, ¹³ C-labeled 7-chloride biphenyl [manufactured by Wellington, “MBP-170 (IUPAC No. 170)”, 2,2 ′, 3,3 ′, 4,4 as a syringe spike ', 5-heptachloro [ ¹³ C ₁₂ ] biphenyl (2,2', 3,3 ', 4,4', 5-Heptachloro [ ¹³ C ₁₂ ] biphenyl)] was added to prepare a sample solution, and gas chromatography PCBs were quantified using a quadrupole mass spectrometer [GC-QMS apparatus] to determine the recovery rate. The results are shown in Table 2. In the analysis by the GC-QMS method, no peak derived from the coexisting substance could be confirmed.

The configuration and conditions of the used GC-QMS apparatus are as follows.
Gas chromatograph part column: capillary column [length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm]
Liquid phase: 5% phenylmethyl silicon [manufactured by J & W, “DB-5MS”]
Column temperature: After injection, 90 ° C. is maintained for 1 minute, and then the temperature is increased to 200 ° C. at 16 ° C./minute, then to 300 ° C. at 6 ° C./minute, and the same temperature is maintained for 5 minutes.
Injection method: Splitless method, purge start time 1.5 minutes Injection amount: 1 μL
Inlet temperature: 280 ° C
Carrier gas: Helium gas, 1 mL / min Interface temperature: 250 ° C

Mass spectrometer ionization method: EI
Ion source temperature: 250 ° C
Ionization energy: 70 eV
Detection mode: SIM method cycle time: 1.0 sec or less

Example 2
In place of the fuming sulfuric acid used in Example 1 (free SO ₃ concentration 25%), fuming sulfuric acid having a free SO ₃ concentration of 20% by mass (manufactured by Kanto Chemical Co., Ltd., “reagent grade”) was used to collect the simulated insulating oil. Except that the amount was 354 μL (corresponding to 0.3 g), the operation was carried out in the same manner as in Example 1, and GC-QMS analysis was performed to obtain the recovery rate. The results are shown in Table 2. In the GC-QMS analysis, no peak derived from the coexisting substance could be confirmed.

Example 3
In place of the fuming sulfuric acid used in Example 1 (free SO ₃ concentration 25%), fuming sulfuric acid having a free SO ₃ concentration of 15% by mass (manufactured by Kanto Chemical Industry Co., Ltd., “reagent grade”) was used to collect the simulated insulating oil. Except that the amount was 354 μL (corresponding to 0.3 g), the operation was carried out in the same manner as in Example 1, and GC-QMS analysis was performed to obtain the recovery rate. The results are shown in Table 2. In the GC-QMS analysis, no peak derived from the coexisting substance could be confirmed.

Example 4
Example 1 except that fuming sulfuric acid (manufactured by Kanto Chemical Co., Ltd., “reagent grade”) having a free SO ₃ concentration of 10% by mass was used instead of the fuming sulfuric acid (free SO ₃ concentration 25%) used in Example 1. In the same manner as described above, GC-QMS analysis was performed to obtain the recovery rate. The results are shown in Table 2. In the GC-QMS analysis, no peak derived from the coexisting substance could be confirmed.

Example 5
Instead of the silica gel for the preparation of fuming sulfuric acid impregnated silica gel used in Example 1, silica gel having a BET specific surface area of 341 m ² / g and a pore volume of 1.66 cm ² / g was used, and the amount of simulated insulating oil collected was 295 μL (0 ¹³ C labeled 7-chloride biphenyl (manufactured by Wellington, “MBP-170 (IUPAC No. 170)”) and ¹³ C-labeled trichloride biphenyl (manufactured by Wellington, “MBP- 37 (IUPAC No. 37) ", except that 3,4,4'-trichloro [ ¹³ C ₁₂ ] biphenyl (3,4,4'-Trichloro [ ¹³ C ₁₂ ] biphenyl)] was added. A sample solution was prepared by operation, and PCBs were quantified by a gas chromatograph-double focusing mass spectrometer [GC-HRMS apparatus] to obtain a recovery rate. The results are shown in Table 2. In the analysis by the GC-HRMS method, a peak derived from a coexisting substance could not be confirmed.

The configuration and conditions of the used GC-HRMS apparatus are as follows.
Gas chromatograph part column: capillary column [length: 60 m, inner diameter: 0.25 mm]
Liquid phase: 8% phenyl polycarborane [SGE “HT8-PCB”]
Column temperature (analysis of 1 chlorine body to 4 chlorine body): After injecting the n-hexane sample, after maintaining 90 ° C. for 1 minute, the temperature was raised to 200 ° C. at 20 ° C./minute, and then 275 at 4 ° C./minute. Then, the temperature is raised to 310 ° C. at 20 ° C./min, and the same temperature is maintained for 5 minutes.
Column temperature (analysis of 5 chlorine bodies to 10 chlorine bodies): After injecting the n-hexane sample, after maintaining 90 ° C. for 1 minute, the temperature was raised to 200 ° C. at 20 ° C./minute and then 320 ° C. at 4 ° C./minute. The temperature is raised to 0 ° C., and the same temperature is maintained for 3.5 minutes.
Injection method: Splitless method, purge start time 0.9 minutes Injection amount: 1 μL
Inlet temperature: 280 ° C
Carrier gas: Helium gas, 1 mL / min Interface temperature: 280 ° C

Mass spectrometer ionization method: EI
Ion source temperature: 280 ° C
Ionization energy: 35 eV
Detection mode: SIM method cycle time: 1.0 sec or less

Table 2
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Free SO ₃ concentration Recovery (%)
(Mass%) 3 Chlorine 4 Chlorine 5 Chlorine 6 Chlorine 7 Chlorine 8 Chlorine ━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━
Example 1 25 74 96 110 119 117 118
Example 2 20 72 101 107 111 111 108
Example 3 15 81 108 111 112 114 112
Example 4 10 94 114 118 115 115 114 97
Example 5 25 82 100 103 111 131 99
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Example 6
Non-Patent Document 1 [July 3, 1992, revised by Ministry of Health, Labor and Welfare Notification No. 633, December 28, 2000, the total content of PCBs contained in 1 g of three types of used insulating oil Measurements were made in accordance with Schedule No. 192, Schedule 2, “Standard Verification Methods for Specially Controlled General Waste and Specially Controlled Industrial Waste”, as shown in Table 3.

Table 3
━━━━━━━━━━━━━
Insulating oil A 18mg / kg
Insulating oil B 28mg / kg
Insulating oil C 37mg / kg
━━━━━━━━━━━━━

[Preparation of fuming sulfuric acid impregnated silica gel]
Instead of fuming sulfuric acid (free SO ₃ concentration 25%) used in Example 1, fuming sulfuric acid (manufactured by Kanto Chemical Co., Ltd., “reagent special grade”) having a free SO ₃ concentration of 10% by mass was used. A fuming sulfuric acid impregnated silica gel was prepared.

[Pretreatment of insulating oil]
Dilute 0.25 g of insulating oil with n-hexane (Wako Pure Chemical Industries, “residual agricultural chemicals / PCB test 300”) and inject it into a gel permeation chromatograph [GPC device] to separate the PCB elution range. I took it. This fractionated solution was concentrated under reduced pressure to about 0.5 mL with a rotary evaporator.

Next, a 5 mL polypropylene disposable syringe is used as a column, and a glass fiber filter paper (manufactured by ADVANTEC, GA-100) is laid on the bottom, and silica gel (Wako Pure Chemical Industries, “Wakogel DX”) 0.5 g Then, 1 g of fuming sulfuric acid impregnated silica gel prepared above and 1 g of anhydrous sodium sulfate [manufactured by Wako Pure Chemical Industries, Ltd., “for residual agricultural chemical test”] were packed in this order to prepare a fuming sulfuric acid impregnated silica gel column.

From the top of this column, the sample solution obtained above was transferred, n-hexane was added, and 8 mL of the first effluent was recovered from the bottom of the syringe. This eluate contains PCB. The eluate was concentrated by blowing nitrogen, and made up to 1 mL with n-hexane.

[Quantification of PCBs by GC / ECD method]
About n-hexane sample liquid obtained above, PCBs were quantified by the gas chromatograph (with an ECD detector) [GC / ECD apparatus], and recovery was calculated. The results are shown in Table 4. Further, a foreign substance appearing in the vicinity of the PCB peak was regarded as PCB, and the remaining amount was calculated (PCB conversion value). The results are shown in Table 5.

The configuration and conditions of the used GC / ECD apparatus are as follows.
Gas chromatograph column: glass column [length 2 m, inner diameter 3.2 mm]
Liquid phase: 2% Silicone OV-17 Chromosorb W AW-DMCS 60/80 [Chromatopackings Center Shinwa Kako Co., Ltd.]
Column temperature: 225 ° C
Injection volume: 5 μL
Inlet temperature: 230 ° C
Carrier gas: Nitrogen gas, 40 mL / min

ECD temperature: 230 ° C
Current: 0.5nA

Example 7
The GC / ECD analysis was performed in the same manner as in Example 6 except that fuming sulfuric acid having a free SO ₃ concentration of 5% by mass was used instead of the fuming sulfuric acid used in Example 6 (free SO ₃ concentration of 10%). The recovery rate and the remaining amount of impurities were determined. The results are shown in Tables 4 and 5.

Comparative Example 1
Instead of the fuming sulfuric acid [free SO ₃ concentration 10%] used in Example 6, concentrated sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd., concentration 98 mass% or more, “reagent special grade”) was 44 mass% with respect to the carrier silica gel. GC / ECD analysis was performed in the same manner as in Example 6 except that the sulfuric acid-impregnated silica gel added, mixed, and prepared was used, and the remaining amount of impurities was determined. The results are shown in Table 5.
It can be seen that the fuming sulfuric acid impregnated silica gel can reduce impurities that interfere with the GC / ECD measurement of PCB by about 40% compared to the sulfuric acid impregnated silica gel.

Table 4
━━━━━━━━━━━━━━━━━━━━━━━━━━
Free SO ₃ concentration Total PCB recovery rate (%)
(Mass%) Insulating oil A Insulating oil B Insulating oil C
━━━━━━━━━━━━━━━━━━━━━━━━━━
Example 6 10 74 96 110
Example 7 5 72 101 107
━━━━━━━━━━━━━━━━━━━━━━━━━━

Table 5
━━━━━━━━━━━━━━━━━━━━━━━━━━
Free SO ₃ concentration Contaminant (PCB conversion value mg / kg)
(Mass%) Insulating oil A Insulating oil B Insulating oil C
━━━━━━━━━━━━━━━━━━━━━━━━━━
Example 6 10 1.6 3.2 5.1
Example 7 5 1.7 3.5 5.4
Comparative Example 1 0 2.6 5.5 8.5 8.5
━━━━━━━━━━━━━━━━━━━━━━━━━━

Claims (6)

When quantifying polychlorinated biphenyls in a hydrophobic sample containing polychlorinated biphenyls, the pretreatment step includes a step of contacting the hydrophobic sample with fuming sulfuric acid-impregnated silica gel that satisfies the following conditions: The method for quantifying the polychlorinated biphenyls.
Oleum impregnated silica gel: BET specific surface area of 250m ² / g~450m ² / g, pore volume 1.
4cm ³ /g~2.6cm ³ / in g of silica gel, free SO ₃ concentration of 5% to 40% by weight
The fuming sulfuric acid is impregnated, and the impregnation amount of the fuming sulfuric acid is 0 with respect to the silica gel.
. Fumed sulfuric acid impregnated silica gel with 5 to 2.5 mass times The quantitative determination method according to claim 1, wherein an impregnation amount of the fuming sulfuric acid is 2 mass times or more with respect to the silica gel. The method according to claim 1 or 2, wherein the method is brought into contact with the fuming sulfuric acid impregnated silica gel column packed in a column. A fuming sulfuric acid impregnated silica gel used for pretreatment when quantifying polychlorinated biphenyls in a hydrophobic sample containing polychlorinated biphenyls,
BET specific surface area of 250m ² / g~450m ² / g, pore volume 1.4cm ³ /g~2.6cm ³
/ G of silica gel is impregnated with fuming sulfuric acid having a free SO ₃ concentration of 5% by mass to 40% by mass, and the impregnation amount of the fuming sulfuric acid is 0.5 mass times to 2.5 times the silica gel. Fumed sulfuric acid impregnated silica gel with mass times. The fuming sulfuric acid-impregnated silica gel according to claim 4, wherein an impregnation amount of the fuming sulfuric acid is 2 mass times or more with respect to the silica gel. A silica gel column used for pretreatment when quantifying polychlorinated biphenyls in a hydrophobic sample containing polychlorinated biphenyls;
A silica gel column in which the fuming sulfuric acid-impregnated silica gel according to claim 4 or 5 is packed in a column.