HJ 650-2013Soil and sediment Determination of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) Isotope dilution HRGC-LRMS (English PDF)

3.1 Terms and definitions

3.1.1 Dichlorinated dibenzodioxins (PCDDs) and Polychlorinated dibenzofurans

(PCDFs)

A collective term for polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).

3.1.2 Congener Congener

All compounds of dioxins are similar to each other. There are 210 congeners in the dioxin class.

3.1.3 2,3,7,8-chlorinated dioxins PCDDs/PCDFs isomer substituted at 2,3,7,8-positions Refers to dioxin-like congeners with chlorine atoms at the 2, 3, 7, and 8 positions. Among them, there are 7 kinds of polychlorinated dibenzo-p-dioxins.

There are 10 kinds of chlorodibenzofurans, and there are 17 kinds, see Table 1.

3.1.4 Dioxin internal standard Internal standard for PCDDs/PCDFs analysis

See Table 2 for the dioxin-like standard substances labeled with known concentrations of isotope (13C or 37Cl). Including sample preparation process Added purified internal standard and injection internal standard.

3.1.5 Toxicity equivalency factor, referred to as TEF

Refers to the ratio of dioxin-like congeners to 2,3,7,8-tetrachlorodibenzo-p-dioxin to aromatic hydrocarbon (Ah) receptor affinity.

3.1.6 Toxic equivalent quantity, referred to as TEQ

The mass fraction of each dioxin-like congener is converted to the equivalent mass of 2,3,7,8-tetrachlorodibenzo-p-dioxin Fraction, toxic equivalent mass fraction is the product of the measured mass fraction and the toxic equivalent factor of the isomer.

Table 1 Detection limits of 2,3,7,8-chlorodioxins and methods

Serial number isomer name short name detection limit (ng/kg) 1 2,3,7,8-tetrachlorodibenzo-p-dioxin 2,3,7,8-T4CDD 0.3 2 1,2,3,7,8-pentachlorodibenzo-p-dioxin class 1,2,3,7,8-P5CDD 0.5 3 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin class 1,2,3,4,7,8-H6CDD 0.6 4 1,2,3,6,7,8-hexachlorodibenzo-p-dioxin class 1,2,3,6,7,8-H6CDD 0.6 5 1,2,3,7,8,9-hexachlorodibenzo-p-dioxin class 1,2,3,7,8,9-H6CDD 0.6 6 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin class 1,2,3,4,6,7,8-H7CDD 1.2 7 octachlorodibenzo-p-dioxin OCDD 1.7 8 2,3,7,8-tetrachlorodibenzofuran 2,3,7,8-T4CDF 0.2 9 1,2,3,7,8-pentachlorodibenzofuran 1,2,3,7,8-P5CDF 0.3 10 2,3,4,7,8-pentachlorodibenzofuran 2,3,4,7,8-P5CDF 0.3 11 1,2,3,4,7,8-hexachlorodibenzofuran 1,2,3,4,7,8-H6CDF 0.4 12 1,2,3,6,7,8-hexachlorodibenzofuran 1,2,3,6,7,8-H6CDF 0.4 13 1,2,3,7,8,9-hexachlorodibenzofuran 1,2,3,7,8,9-H6CDF 0.4 14 2,3,4,6,7,8-hexachlorodibenzofuran 2,3,4,6,7,8-H6CDF 0.4 15 1,2,3,4,6,7,8-heptachlorodibenzofuran 1,2,3,4,6,7,8-H7CDF 1.4 16 1,2,3,4,7,8,9-heptachlorodibenzofuran 1,2,3,4,7,8,9-H7CDF 1.4 17 octachlorodibenzofuran OCDF 1.4

Table 2 Available Dioxin Internal Standards

Replace the number of chlorine atoms PCDDs PCDFs Tetrachloro 37Cl4-2,3,7,8-T4CDD 13C12-2,3,7,8-T4CDD 13C12-1, 2, 3, 4-T4CDD 13C12-1, 2, 7, 8-T4CDF 13C12-2,3,7,8-T4CDF Pentachloro 13C12-1,2,3,7,8-P5CDD 13C12-2,3,4,7,8-P5CDF 13C12-1,2,3,7,8-P5CDF Hexachloro 13C12-1, 2, 3, 7, 8, 9-H6CDD 13C12-1, 2, 3, 4, 7, 8-H6CDD 13C12-1,2,3,6,7,8-H6CDD 13C12-2,3,4,6,7,8-H6CDF 13C12-1,2,3,6,7,8-H6CDF 13C12-1,2,3,4,7,8-H6CDF 13C12-1,2,3,7,8,9-H6CDF Heptachlor 13C12-1,2,3,4,6,7,8-H7CDD 13C12-1,2,3,4,7,8,9-H7CDF Octachloro 13C12-OCDD 13C12-OCDF

3.2 Symbols and abbreviations

3.2.1 PCDDs Polychlorinated dibenzo-p-dioxins

Polychlorinated dibenzo-p-dioxin. There are 75 similar species.

3.2.2 PCDFs Polychlorinated dibenzofurans

Polychlorinated dibenzofuran. There are 135 similar species.

3.2.3 T4CDDs Tetrachlorodibenzo-p-dioxins

Tetrachlorodibenzo-p-dioxin. There are 22 isomers.

3.2.4 P5CDDs Pentachlorodibenzo-p-dioxins

Pentachlorodibenzo-p-dioxin. There are 14 isomers.

3.2.5 H6CDDs Hexachlorodibenzo-p-dioxins

Hexachlorodibenzo-p-dioxin. There are 10 isomers.

3.2.6 H7CDDs Heptachlorodibenzo-p-dioxins

Heptachlorodibenzo-p-dioxin. There are 2 isomers.

3.2.7 OCDD Octachlorodibenzo-p-dioxin

Octachlorodibenzo-p-dioxin. There is 1 isomer.

3.2.8 T4CDFs Tetrachlorodibenzofurans

Tetrachlorodibenzofuran. There are 38 isomers.

3.2.9 P5CDFs Pentachlorodibenzofurans

Pentachlorodibenzofuran. There are 28 isomers.

3.2.10 H6CDFs Hexachlorodibenzofurans

Hexachlorodibenzofuran. There are 16 isomers.

3.2.11 H7CDFs Heptachlorodibenzofurans

Heptachlorodibenzofuran. There are 4 isomers.

3.2.12 OCDF Octachlorodibenzofuran

Octachlorodibenzofuran. There is 1 isomer.

3.2.13 RRF Relative response factor

Relative response factor.

3.2.14 HRGC High-resolution gas chromatography

High resolution gas chromatography.

3.2.15 LRMS Low-resolution mass spectrometry

Low resolution mass spectrometer.

3.2.16 SIM selective ion monitoring

Select ion detection.

3.2.17 EI electron impact ionization

Electron bombardment ionization

3.2.18 S/N signal/noise ratio

Signal to noise ratio

3.2.19 PCBs polychlorinated biphenyls

Polychlorinated biphenyl

5.1 Acetone ((CH3)2CO)

5.2 Toluene (C7H8)

5.3 N-hexane (n-C6H14)

5.4 Methanol (CH3OH)

5.5 Dichloromethane (CH2Cl2)

5.6 anhydrous sodium sulfate (NaSO4). excellent grade pure, calcined at 660 ° C for 6 h in muffle furnace before use, after cooling to 150 ° C, turn Move to a desiccator, cool it, put it into a reagent bottle, and store it dry.

5.7 Hydrochloric acid solution. excellent grade, 1 1.

5.8 Sulfuric acid. excellent grade, rho (H2SO4) = 1.84g/ml.

5.9 sodium hydroxide solution. c (NaOH) = 1 mol/L.

5.10 10% silver nitrate silica gel. commercially available, stored in a desiccator.

5.11 Reduction of copper

Rinse with hydrochloric acid (5.7), distilled water, acetone (5.1), and toluene (5.2) before use, and store in a desiccator.

5.12 Silicone

The chromatographic silica gel (100 ~.200 mesh) was placed in a beaker and washed with dichloromethane (5.5) until the dichloromethane was completely After the hair is spread, placed in an evaporating dish or beaker, the thickness is less than 10mm, heated at 130 ° C for 18h, placed in a desiccator Cool for 30 min. Put it in a closed container and store it in a desiccator.

5.13 Sodium hydroxide alkaline silica gel. omega = 33%

Take 67g of silica gel (5.12), add 33g of sodium hydroxide solution (5.9) at a concentration of 1mol/l, stir well to make it the fluid is in the form of a powder. After the preparation is completed, it is sealed in a reagent bottle and stored in a desiccator.

5.14 Silicate Sulfuric Acid. omega=44%

100 g of silica gel (5.12) was taken, and 78.6 g of sulfuric acid (5.8) was added thereto, and after fully shaking, it became a powder. After the preparation is completed Seal into the reagent bottle and store in the desiccator.

5.15 Alumina

Alumina for chromatography (basic activity I). Activated alumina can be used directly during the analysis. If necessary the activation method is as follows. the alumina is placed in a beaker and the thickness is less than 10 mm, and heated at 130 ° C for 18 hours.

Or spread in a Petri dish to a thickness of 5 mm, heat at 500 ° C for 8 h, and cool in a desiccator for 30 min. Load the container is sealed and placed in a desiccator for storage. It should be used as soon as possible after activation.

5.16 Activated carbon dispersing silica gel. commercially available and stored in a desiccator.

5.17 Nitrogen. High purity nitrogen, 99.999%.

5.18 Water. Distilled water thoroughly washed with n-hexane (5.3). Unless otherwise stated, the water referred to in this standard refers to the above Treated distilled water.

5.19 Dichloromethane-n-hexane solution. 3% (v/v)

Methylene chloride and n-hexane were mixed in a volume ratio of 3.97.

5.20 Dichloromethane-n-hexane solution. 50% (v/v)

Methylene chloride and n-hexane were mixed in a volume ratio of 1.1.

5.21 Dichloromethane-n-hexane solution. 25% (v/v)

Methylene chloride and n-hexane were mixed in a volume ratio of 1.3.

5.22 Sodium chloride solution. rho (NaCl) = 0.15 g/ml. 150 g of sodium chloride was dissolved in water and diluted to 1 L.

5.23 Alkaline detergent. commercially available.

5.24 Calibration Standards. Commercially available dioxin calibration standards, covering 17 different chlorine-substituted dioxins and furans, see attached Record B.

5.25 Purification of internal standard. Commercially available dioxins to purify internal standard substances, generally 8-17 kinds of 13C labeled compounds are selected as purification internal standards.

See Appendix B.

5.26 Injecting internal standard. Commercially available dioxin-like injection internal standard substance, generally choose 1 2 kinds of 13C labeled compounds as injection internal standard.

See Appendix B.

5.27 Perfluorotributylamine (PFTBA) calibration tuning standard solution, commercially available.

6.1 Sampling device

6.1.1 Sampling tool. It should meet the requirements of HJ/T 166 and GB 17378.3, and use stainless steel which has no adsorption to dioxin.

Steel or aluminum alloy appliances.

6.1.2 Sample container. It should meet the requirements of HJ/T 166 and GB 17378.3, and use stainless steel which has no adsorption to dioxin.

Steel or glass sealables.

6.2 Pre-processing device

The sample pretreatment device should be thoroughly washed with alkaline detergent (5.23) and water, and acetone (5.1) and positively used before use.

Rinse with a solvent such as alkane (5.3) or toluene (5.2) and perform a blank test periodically. Grease is strictly prohibited at all interfaces.

6.2.1 Soxhlet extractor or equivalent device

6.2.2 Concentration device. rotary evaporation concentrator, nitrogen blowing instrument and equivalent concentrating device.

6.2.2 Rapid extraction device. with 34ml and 66ml extraction tank, the extraction pressure is not less than 1500psi, the extraction temperature needs to be large at 120 ° C.

6.2.3 Chromatography column. inner diameter 8~15mm, length.200~300mm glass column.

6.3 Analytical instrument

Dioxins were analyzed using high resolution gas chromatography-low resolution mass spectrometry (HRGC-LRMS).

6.3.1 High-resolution gas chromatography. The injection part adopts on-column injection or splitless injection, the maximum use temperature of the inlet 250 ~ 280 ° C.

6.3.1.1 Quartz capillary column. length 25~60m, inner diameter 0.1~0.32mm, film thickness 0.1~0.25µm quartz hair Thin tube column for good separation of 2,3,7,8-position chloro-substituted isomers and identification of chromatographic peaks of these compounds Out order. In order to ensure good separation of all 2,3,7,8-position chloro-substituted isomers, it is advisable to choose 2 different polarities.

Capillary columns were measured separately.

6.3.1.2 Oven temperature. The temperature control range is 50~350°C, which can be programmed.

6.3.2 Low Resolution Mass Spectrometry

Ion source temperature, 250 ° C; electron bombardment (EI) mode; electron bombardment energy, 70 eV; selective ion detection method (SIM law).

6.3.3 Carrier gas. high purity helium (purity of 99.999% or more).

7.1 Acquisition and preservation

7.1.1 Sampling in accordance with HJ/T 166 and GB 17378.3. After the sample is collected, save it in the dark and send it to the laboratory as soon as possible.

Sample preparation and sample analysis. Instruments, materials, etc. used for sample collection should be kept clean and water and organic should be used before sampling.

Solvent cleaning.

7.1.2 According to the requirements of HJ/T 166 and GB 17378.3, the collected samples are air-dried, crushed and sieved in the laboratory. save in a brown glass bottle.

7.1.3 Determination of moisture content

The soil moisture content was determined by reference to HJ 613.

7.2 Preparation of samples

The preparation of the sample mainly includes the addition of the purification internal standard, the extraction of the sample, the various purification of the extraction liquid, the concentration of the purification liquid, for the addition of the internal standard of injection, the flow chart of the pretreatment process is shown in Appendix C.

7.2.1 Sample extraction

7.2.1.1 Soxhlet extraction

Weigh about 20g of air-dried sieved sample into the extraction cup of the Soxhlet extractor, and add 1ng of 13C12-standard to each sample.

Remember to purify the internal standard. Extract with about.200 ~ 300 ml of toluene (5.2) for more than 16 hours. Concentrate the extract to 1~2ml, set Allow 5ml to be purified.

7.2.1.2 Rapid extraction method

Weigh about 20g of air-dried sieved sample in a small beaker, add a certain amount of anhydrous sodium sulfate (5.6), and transfer the sample to A certain amount of 13C12-labeled purification internal standard was added to the extraction cell of the rapid extraction apparatus. The set extraction conditions are. pressure the pressure is 1500 psi, the temperature is 120 ° C, the solvent toluene (5.2) is extracted, the 100% is filled in the extraction cell mode, and the high temperature and high pressure are allowed to stand for 5 min.

Cycle three times. The extracted sample is concentrated to volume according to the method of 7.2.1.1 and to be purified.

7.2.1.3 If the sediment sample contains a large amount of sulfide, desulfurization purification is required. The desulfurization method is as follows. the sample extract is concentrated Reduce to about 50ml, add the treated reduced copper, shake well, filter, collect the filtrate, and concentrate according to 7.2.1.1 Rong.

7.2.2 Purification of samples

7.2.2.1 Sulfuric acid-silica column purification.

When the sample color is darker and the interference is large, the sulfuric acid-silica gel column purification method is adopted.

7.2.2.1.1 Place the 7.2.1 concentrated sample into a 250 ml separatory funnel, add 75 ml of n-hexane (5.3), and use 30 ml.

The sulfuric acid (5.8) was shaken for about 10 min. After standing, the aqueous phase was discarded and the operation was repeated until the sulfuric acid layer was colorless. The n-hexane layer is 50ml l5% the sodium chloride solution (5.22) is washed repeatedly to neutrality, dehydrated by anhydrous sodium sulfate (5.6), and concentrated to less than 2 mL, according to 7.2.2.1.2 or 7.2.2.2 The method continues to purify.

7.2.2.1.2 Add glass wool to the bottom of the glass column, fill in 3g silica gel (5.12), and add about 10mm thick in the upper part.

Anhydrous sodium sulfate (5.6).

7.2.2.1.3 Rinse the silica gel column with 50 ml of n-hexane (5.3) and keep the liquid level above the anhydrous sodium sulfate layer. Sample concentrate Slowly transfer to the silica gel column, and then repeatedly wash the concentrate bottle with 1 ml of n-hexane, and transfer to the silica gel column until the liquid level is reduced to anhydrous.

Below the sodium sulfate layer, rinse with 120 ml of n-hexane at a flow rate of 2.5 ml/min (1 drop per second). Eluent concentrator Concentrate to about 1 ml for further processing.

Note 1. In the case of glass column chromatography, the conditions for fractional collection of fractions vary with the type of filler, activity or type of solvent, and amount of solvent.

For the change, a sample containing all the dioxins, such as a coal ash extract, was subjected to a stepwise experiment to determine the conditions before the operation.

7.2.2.2 Multi-layer silica gel column purification

7.2.2.2.1 Add some glass wool at the bottom of the glass column (inner diameter 15mm), and weigh 3g silica gel (5.12), 5g 33% Sodium hydroxide alkaline silica gel (5.13), 2g silica gel (5.12), 10g 44% sulfuric acid silica gel (5.14), 2g silica gel (5.12), 5g 10% Silver nitrate silica gel (5.10) and 5 g anhydrous sodium sulfate (5.6).

7.2.2.2.2 Rinse with 50 ml of n-hexane and keep the liquid above the anhydrous sodium sulfate layer.

7.2.2.2.3 Take the extract of 7.2.1 and remove the toluene with nitrogen. The amount of liquid remaining is about 0.5 ml. Slowly inject the concentrate into the glass in the glass column, the liquid level is maintained at the upper end of the column filling portion. The flask was washed repeatedly with 1 ml of n-hexane and transferred to glass.

On the glass column.

7.2.2.2.4 Place 120 ml of n-hexane in a separatory funnel over the silica gel column and slow down at a flow rate of 2.5 ml/min (1 drop per second).

Slowly drip into the silica gel column for rinsing.

7.2.2.2.5 The eluent was concentrated to 1 ml with a concentrator for further processing. If the color of the filling part becomes darker or penetrates for the phenomenon, the operation of 7.2.2.2 should be repeated.

7.2.2.3 Activated alumina purification

7.2.2.3.1 Add glass wool to the bottom of the glass column and fill in 20g of activated alumina (5.15) and add it to the top.

10 mm thick anhydrous sodium sulfate was rinsed with 50 ml of n-hexane. The liquid level is maintained in the upper part of the sodium sulfate.

7.2.2.3.2 Slowly transfer the 7.2.2.1 or 7.2.2.2 purified sample solution to the alumina column and repeat it with 1ml of hexane.

The vessel was washed and the eluent was transferred to an alumina column. When the liquid level of the sample solution is in the lower part of the sodium sulfate layer, 70 ml of toluene is added.

The solution was rinsed and all the eluent was discarded after the toluene had flowed out. Add 30ml of n-hexane and collect the part of the eluent for Part A.

Points, mainly containing substances such as polychlorinated biphenyls. Then use 220ml 50% (v/v) dichloromethane - n-hexane solution (5.20) to 2.5ml/min Rinse at a rate of 1 drop per second to obtain a portion B of the eluent. This part of the solution contains dioxins. Then use the column was rinsed with 50 ml of dichloromethane until it no longer flowed out to give the eluent C fraction. Keep Part A and Part C until testing the end is complete (Parts A and C can be combined).

7.2.2.3.3 Concentrate the Part B eluent to less than 1 ml with a concentrator and transfer to a 5 ml concentrating tube (or proceed directly to 7.2.2.4 Step operation), blow to near dry with nitrogen, add injection internal standard, and make up to 20µl with decane or toluene, transfer into 100µl sample in quality control, the package is to be analyzed by the instrument.

Note 2. The activity of alumina varies greatly with the production batch number and the storage time after opening. 1,3,6,8-T4CDD when activity is reduced and 1,3,6,8-T4CDF may be dissolved in the first part of the eluent, while the octachlorate is used in a specified amount by 50% dichloromethane-n-hexane solution.

It cannot be eluted in the second part of the eluent. Therefore, before the operation, a step-by-step experiment is carried out using a sample containing all dioxin such as a coal ash extract.

Determine the conditions.

7.2.2.4 Small activated alumina column purification

This step can be operated when the method is not well cleaned by the method of 7.2.2.3. Add a small amount to the head of the disposable dropper Glass wool, weigh 1 g of activated alumina (5.15) on a dropper, and add 5 ml of n-hexane to rinse the chromatography tube. Waiting for yourself when the alkane solution is in the upper part of the alumina, transfer the concentra...