GB/T 4919-1985 Determination of total nitro compounds in industrial wastewater - Gas chromatography

This method is applicable to the determination of major nitro compounds such as mononitrotoluene, dinitrotoluene, trinitrotoluene and their isomers in TNT production wastewater and discharged wastewater (excluding nitro compound salts). GB/T 4919-1985 Determination of total nitro compounds in industrial wastewater by gas chromatography GB/T4919-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of total nitro compounds in industrial wastewater
Gas chromatographic method
Waste water from manufacturing process-Determination of total nitro compounds-Gas chromatographic method
LDC 628.54
GB 4919-85
This method is applicable to the determination of major nitro compounds such as nitrotoluene, dinitrotoluene, trinitrotoluene and their isomers in TNT production wastewater and discharged wastewater (excluding salts of nitro compounds). Total nitro compounds refer to the sum of major nitro compounds such as mononitrotoluene, dinitrotoluene, dinitrotoluene and their isomers contained in wastewater.
Gas chromatography is to determine the sum of the contents of several major nitro compounds in wastewater, which is called total nitro compounds. Spectrophotometry is used to determine the nitro compounds (calculated as 2.4,6-trinitrotoluene) and the sum of mononitro compounds and dinitro compounds (calculated as 2.4-dinitrotoluene) in wastewater. 1 Principle
1.1 A separation column with 15% SE-30 stationary liquid is coated on the surface of the diatom 7 (Celite) support. Under certain operating conditions, due to the different separation coefficients of each compound in the gas-liquid two phases when it moves forward with the carrier gas, the time for the guest compound to flow out is different. The content of each nitro compound is determined by the external standard method using a hydrogen flame identifier. 1.2 When trinitrobenzoic acid and trinitrotoluene coexist in the wastewater, the trinitrobenzoic acid peaks and trinitrobenzene peaks are simultaneously occupied during the heating reaction, and the positions cannot be separated. In order to determine the contents of trinitrobenzoic acid and trinitrobenzene respectively, two solvent systems are used to extract and measure their concentrations respectively. Both trinitrobenzene benzoic acid and trinitrobenzene can be extracted by acetic acid ester and benzene, while carbon disulfide-chloromethane mixed extractant can only extract trinitrobenzene. If the wastewater does not contain trinitrobenzoic acid, the mixed extractant can be used for extraction once, and the determination of each nitro compound component can be completed without concentration.
1.3 The minimum detection concentration of this method is shown in Table 1.
-Nitrobenzene
O-nitrobenzene
Para-nitrotoluene
2.6-Dinitrotoluene
2, 4-Dinitrotoluene
2,4, 6-Trinitrotoluene
2 Instruments
In addition to the generally applicable chemical analysis instruments, only the National Environmental Protection Agency 1985-01-18 issued 176
Palace small detection concentration
1985-08-01 implementation
2.1 Gas chromatograph with flame detector. 2.2 Micro syringe, 1, 10l.
. Reagents
GB4919-85
The reagents used in this method, except those specified, are analytically pure, and all percentage concentrations except those specified are weight volume percentage (w).
Carbon trisulfide.
8.2 Dichloromethane.
Methyl acetate.
Nitromethane.
Carbon disulfide-dichloromethane mixed extractant mixing ratio is 9:1 (V/V). 3.8
Stationary liquid: SE-30.
8.8Support: Celite 60~80 days.
Standard samples of various nitro compounds.
4 Preparation of various nitro compound standard samples 4.1 Preparation of mixed water standard sample (liquid A)
For the preparation of water standard sample for wastewater that does not contain trinitrobenzoic acid: weigh 0.002-0.003g nitrobenzene, 0.003-0.004g o-nitrotoluene, 0.004-0.005g p-nitrotoluene, 0.009-0.01g 2,6-dinitrotoluene, 0.05-0.06g 2, 4-dinitroformate, 0.025-0.03g 2,4,6-trinitrotoluene (accurate to 0.0001g), add 2-3% concentrated sulfuric acid. ml, stir until completely dissolved, carefully transfer to a 1000ml volumetric flask filled with distilled water, dilute to the mark after complete dissolution, and place in a dark place for later use. This solution contains about 0.1mg/ml of total nitro compounds.
*.2 Preparation of mixed standard (solution B)
For the preparation of a standard containing trinitrobenzoic acid in water: weigh 0.02~0.03g of o-nitrotoluene, 0.03~0.035 g para-nitrotoluene, 0.01~0.015g 2,6-dinitrotoluene, 0.030.04g 2,4-dinitrotoluene, 0.03~0.035g 2,4,6-trinitrotoluene, 0.04~0.045g trinitrobenzene, 0.04~0.045g 2,3,4-trinitrotoluene, 0.030.04g 2,4,5-trinitrotoluene (all accurate to 0.0002g): .Dissolve nitromethane in a 25ml volumetric flask, dilute to the mark after it is completely dissolved, and set aside. This solution contains about 10mg/ml of total nitrated substances.
5 Operation steps
5.1 Preparation of chromatographic columns
Weigh 15% of the support's fixed liquid SE-30 and 1% of stearic acid, stir and dissolve them with triazine, then pour them into the weighed and dried support, and soak them in a water bath to evaporate the solvent to dryness. , and then put it in a 110°C oven to dry, and after cooling, install it into a stainless steel column with a length of 2m and a diameter of 4mm. Raise the temperature gradually under nitrogen flow, and continue to heat to above 48°C, and age until the baseline is stable. 5.2 Measurement conditions
Hydrogen flame detector temperature: 250°C,
Chromatographic column temperature, 200C
Vaporization chamber temperature: no higher than 290°C
Nitrogen flow rate, 30～35ml /min
Air flow, 600ml/min
Hydrogen flow: 35～40ml/mil.
Retention time of nitro compounds
Peak order
Name of nitro compounds
Nitrobenzene
O-nitrotoluene
Meta-nitrotoluene
Para-nitromethylbenzene
Para-nitroethylbenzene
Para-dinitrobenzene
2,6-dinitrotoluene
Hujian dinitrobenzene
2, 5- Dinitrotoluene
2,4-Dinitrotoluene
2.3-Dinitrotoluene
3,1-Dinitrotoluene
Diphenylamine
Trinitrobenzene
Trinitrobenzene
Trinitrobenzene
2.4.6-Trinitrotoluene
2,3,4-Trinitrotoluene
2,4,5-Trinitrotoluene
3,4.5-Trinitrotoluene
GB4919—85
Retention time, 5
Relative retention time
Confidential distance, mm
Relative retention distance
GB4919—a5
5.4 Drawing of standard working curve (for example, the concentration of nitro compound is 110mg/1) Take 5, 10, 15, 20, 25, 30ml of water standard sample (liquid A) in each separating funnel, add distilled water to dilute to 200ml, add 2 or 3ml of mixed solvent, shake for 5min (exhaust 2-3 times), put it in the storage bottle after separation, and release 1-2ml of water liquid to seal it. Under the specified conditions, use a micro syringe to take 2-4 μl of the lower layer of extraction solvent and inject it into the vaporization chamber. The measured chromatographic peak height multiplied by the distance is the ordinate, and the content of each nitro compound (g) is the abscissa to draw the standard working curve. 5.5 Determination of water samples
§,5.1 Water samples without trinitroformic acid When the water contains less than 1 mg of nitro compounds, take 500 ml of water sample and add 3 or 5 ml of mixed extractant for extraction. When the water contains 1-10 mg of nitro compounds, take 200 ml of water sample and extract with 2 or 3 ml of mixed extraction solvent. When the water contains more than 10 mg/1 of nitro compounds, take 100 ml or less of water sample, dilute to 100 ml or 200 ml with distilled water, and extract with 2 ml or 3 ml of mixed extraction solvent. Take the same volume of water standard sample according to the concentration range of the water sample, extract, inject and attenuate under the same conditions to measure the peak area, and calculate the concentration by external standard method or check the standard curve. 5.5.2 For water samples containing trinitrobenzoic acid, take 20-200 ml according to the concentration of nitro compounds in the water sample, add ethyl acetate (water sample to solvent ratio is 2=1, 5:1, 5:1) to extract 3 times, and extract once with benzene (10:1).Combine the above extractants, blow dry in a 60-70 ℃ water bath, add 1 ml of nitromethane solvent until completely dissolved, and place in a storage bottle. Take 1-2 μl and inject into the vaporizer for separation and determination. At the same time, take 1-2 μl of standard B solution and inject into the vaporizer for separation and determination. Use this spectrum as the external standard method to calculate the concentration of each component. When dinitrobenzoic acid and trinitrobenzene exist in the wastewater at the same time, it is necessary to determine the content of trinitrobenzene and mononitrobenzene respectively. Another water sample should be taken and extracted with a mixed extraction solvent to determine the content of trinitrobenzene. Calculate the content of the two according to formula (4). The sum of the measured mononitro compound concentration and the dinitro compound and trinitro compound concentrations measured by ethyl acetate extraction is taken as the total nitro compound concentration. 6 Calculation
6.1 Lookup table method
6.1.1 The concentration of each component of nitro compound in the wastewater is calculated according to formula (1). Nitro compounds (mg/1)
Where: C——Corresponding content found from standard working curve, ug; V
-Volume of water sample, ml.
6.1.2Total nitro compound concentration in wastewater, calculated according to formula (2). =EX
Where: Y--Total nitro compound concentration in wastewater, mg/X-Concentration of each component in wastewater, mg/1.
6.2 External standard method
6.2.1Concentration of guest component in wastewater is calculated according to formula (3). X(mg/ 1)=
W, brown sample concentration. mg/l:
V, V, --·- The volume of the standard sample and water sample extraction liquid, μlF, F, — The peak height of each component measured in the standard sample and water sample, mm; F2×H,×S?
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li, {l — The distance from the solvent peak to the peak height of each component of the standard sample and water sample, mm;.(1)
（3）
V The volume of the water sample, m1
GB4819—B5
— The volume of the mixed solvent or nitromethane, ml; SS, The attenuation when measuring the standard sample and water sample t
— The concentration of each component in the wastewater.
6,2.2 The total nitro compound concentration of wastewater 1 is calculated according to formula (2). 6.3 The concentration of trinitrobenzoic acid is calculated according to formula (4). GiNBA(mg/I) =a) -1
Where: CrBA—trinitrobenzoic acid concentration in wastewater, mg/1—trinitrobenzoic acid and trinitrobenzene content determined by ethyl acetate extraction, mg/2—trinitrobenzene content determined by mixed solvent extraction, mg/17 Determination error
7.1 When the concentration is greater than 1 mg/1, the relative error shall not exceed 10%. 7.2 When the concentration is below 1 mg/1, the relative error shall not exceed 15%. 8 Precautions
8.1 The standard samples of 4.1 and 4.2 shall be prepared according to the actual concentration of water pollutant components, and the concentration shall be prepared in the corresponding range, without forcing a single effect. 8.2 During the determination, the conditions shall be strictly controlled to be consistent with the standard working curve. B.3 If the conditions are changed, the standard working curve shall be redone, or a standard push solution with the same concentration as the water sample shall be taken, and the concentration shall be measured by the external standard method, and the sieve concentration shall be counted. 8. When the water sample cannot be measured within 24 hours, sulfuric acid must be added to adjust the p-1i to less than 3. Additional remarks:
This standard was proposed by the former State Council Environmental Protection Leading Group. This standard was drafted by the Fifth Design Institute of the Ordnance Industry Ministry and the State-owned Qingyang Chemical Plant. The main drafters of this standard are Lu Yongsen, Sun Lin, and Yuan Shuqing. This standard is entrusted to the Environmental Protection Department of the Ordnance Industry Ministry for interpretation. T8O
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