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HJ 970-2018

Chinese Standard: 'HJ 970-2018'
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HJ 970-2018English209 Add to Cart Days<=3 Water quality - Determination of petroleum - Ultraviolet spectrophotometric method Valid HJ 970-2018
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BASIC DATA
Standard ID HJ 970-2018 (HJ970-2018)
Description (Translated English) Water quality - Determination of petroleum - Ultraviolet spectrophotometric method
Sector / Industry Environmental Protection Industry Standard
Classification of Chinese Standard Z16;Z23
Word Count Estimation 9,960
Administrative Organization Ministry of Ecology and Environment

HJ 970-2018
Water quality - Determination of petroleum - Ultraviolet spectrophotometric method
National Environmental Protection Standard of the People's Republic
Determination of water quality petroleum
Ultraviolet spectrophotometry (trial)
Water quality - Determination of petroleum -
Ultraviolet spectrophotometric method
Published on.2018-10-10
2019-01-01 Implementation
Ministry of Ecology and Environment released
i directory
Preface ii
1 Scope 1
2 Normative references 1
3 Principle of the method 1
4 interference and elimination..1
5 reagents and materials..1
6 instruments and equipment..2
7 samples..2
8 Analysis step 3
9 Calculation and representation of results 4
10 precision and accuracy. 4
11 Quality Assurance and Quality Control..5
12 Waste treatment.5
13 Notes.5
Foreword
To implement the Law of the People's Republic of China on Environmental Protection, the Law of the People's Republic of China on the Prevention and Control of Water Pollution and the Chinese People
The Marine Environmental Protection Law of the Republic protects the ecological environment, safeguards human health, and regulates the determination methods of petroleum in the water.
Set this standard.
This standard specifies the UV spectrophotometric method for the determination of petroleum in water.
This standard is the first release.
This standard is formulated by the Department of Eco-Environmental Monitoring, the Department of Regulation and Standards of the Ministry of Ecology and Environment.
This standard is mainly drafted by. Tianjin Ecological Environment Monitoring Center and China Academy of Environmental Sciences.
This standard is verified by. Hainan Environmental Monitoring Center Station, Guangxi Zhuang Autonomous Region Marine Environmental Monitoring Center Station, Zhejiang
Zhoushan Marine Ecological Environment Monitoring Station, Qinhuangdao Environmental Monitoring Center of Hebei Province, and National Oceanic Administration Tianjin Seawater Desalination and Integration
The Institute, Beijing Hua Testing Technology Co., Ltd.
This standard is approved by the Ministry of Ecology and Environment on October 10,.2018.
This standard has been implemented since January 1,.2019.
This standard is explained by the Ministry of Ecology and Environment.
1 Determination of water quality - Petroleum spectrophotometry
Warning. The n-hexane used in the experiment is toxic and should be handled in a fume hood while being worn as required.
Protective equipment to avoid contact with skin and clothing.
1 Scope of application
This standard specifies the UV spectrophotometric method for the determination of petroleum in water.
This standard applies to the determination of petroleum in surface water, groundwater and seawater.
When the sample volume is 500 ml and the volume of the extract is 25 ml, the detection limit of the method is 2 cm quartz cuvette.
0.01 mg/L, the lower limit of determination is 0.04 mg/L.
2 Normative references
The contents of this standard refer to the following documents or their terms. For undated references, the valid version is appropriate.
Used in this standard.
GB 17378.3 Marine monitoring specification Part 3. Sample collection, storage and transport
HJ 493 Technical Regulations for Preservation and Management of Water Quality Samples
HJ/T 91 Surface Water and Wastewater Monitoring Technical Specifications
HJ/T 164 Technical Specifications for Groundwater Environmental Monitoring
3 Principle of the method
Under the condition of pH≤2, the oil in the sample is extracted by n-hexane, and the extract is dehydrated by anhydrous sodium sulfate.
After removing the polar substances such as animal and vegetable oils by magnesium silicate, the absorbance is measured at a wavelength of 225 nm, and the petroleum content and absorption are measured.
The luminosity value is in accordance with Lambert-Beer's law.
4 interference and elimination
After the extract is adsorbed by magnesium silicate, the interference of polar substances can be eliminated.
5 reagents and materials
Unless otherwise stated, analytically pure reagents in accordance with national standards were used for the analysis, and the experimental water was distilled water or deionized water.
5.1 Hydrochloric acid. ρ(HCl) = 1.19 g/ml.
5.2 Sulfuric acid. ρ(H2SO4) = 1.84 g/ml.
5.3 n-Hexane (C6H14).
2 Before use, at a wavelength of 225 nm, use water as a reference to measure the light transmittance, and the light transmittance is greater than 90% before use.
Dearomatization treatment. Dearomatization method. Add 500 ml of n-hexane to a 1 000 ml separatory funnel (6.3) and add 25 ml.
The sulfuric acid (5.2) is washed for 10 min, the sulfuric acid phase is discarded, and the above operation is repeated until the sulfuric acid is nearly colorless, and then extracted with distilled water.
Wash 3 times until the light transmittance is greater than 90%.
5.4 Anhydrous ethanol (C2H6O).
5.5 anhydrous sodium sulfate (Na2SO4).
After burning at 550 ° C for 4 h, it was cooled and placed in a ground glass bottle and stored in a desiccator.
5.6 Magnesium silicate (MgSiO3). 150 μm~250 μm (100 mesh to 60 mesh).
After burning at 550 ° C for 4 h, after cooling, weigh the appropriate amount of magnesium silicate in a ground glass bottle, according to the weight of magnesium silicate, press
Add 6% (m/m) of the appropriate amount of distilled water, tightly plug and shake for a few minutes, let stand for 12 h, set aside.
5.7 Petroleum standard stock solution. ρ = 1 000 mg/L.
Direct purchase of commercially available n-hexane systems for certified reference materials/samples as determined by UV spectrophotometry.
5.8 Petroleum standard use solution. ρ=100 mg/L.
Accurately transfer 5.00 ml of petroleum standard stock solution (5.7) to a 50 ml volumetric flask and make up to volume with n-hexane (5.3).
Shake well. Can be saved for 24 h.
5.9 Glass wool.
Dip with n-hexane (5.3) for at least 15 min, dry and place in a dry glass bottle for later use.
5.10 Magnesium silicate adsorption column.
Fill a small amount of glass wool (5.9) at the outlet of the glass column with an inner diameter of 10 mm and a length of about.200 mm, and then add silicic acid.
Magnesium (5.6) is slowly poured into a glass column, tapped gently while pouring, and the filling height is about 80 mm.
6 Instruments and equipment
6.1 Sampling bottle. 500 ml brown hard glass bottle.
6.2 UV spectrophotometer. wavelength.200 nm ~ 400 nm, and equipped with 2 cm quartz cuvette.
6.3 Separating funnel. 1 000 ml with Teflon cock.
6.4 Erlenmeyer flask. 50 ml with a stopper.
6.5 Oscillator. Speed up to 300 r/min.
6.6 Centrifuge. up to 3 000 r/min with 50 ml glass centrifuge tubes.
6.7 Common laboratory utensils and equipment.
7 samples
7.1 Sample collection
Sample collection was carried out in accordance with the relevant regulations of GB 17378.3 and HJ/T 91, HJ/T 164. With sample bottle (6.1)
3 Collect 500 ml samples. After sample collection, acid (5.1) was added to acidify to pH ≤ 2.
7.2 Preservation of samples
Carry out sample storage according to the relevant regulations of GB 17378.3 and HJ 493. If the sample cannot be measured within 24 h, it should be
Store at 0°C~4°C in cold storage and measure within 3 days.
7.3 Preparation of samples
7.3.1 Extraction
Transfer all samples to a 1 000 ml separatory funnel (6.3) and measure 25.0 ml of n-hexane (5.3) for washing and sampling.
After the bottle (6.1), all were transferred to the separatory funnel (6.3). Shake well for 2 min, often open the cock exhaust, static
After stratification, the lower aqueous phase was transferred to a 1 000 ml graduated cylinder and the sample volume was measured and recorded.
Note 1. When the degree of emulsification is heavier, 1 to 4 drops of absolute ethanol (5.4) can be added to the extract after removing the aqueous phase. If the effect is still not
Ideally, it can be transferred to a glass centrifuge tube and centrifuged at 2 000 r/min for 3 min.
Note 2. An automatic extraction device can be used instead of manual extraction.
7.3.2 Dehydration
Transfer the upper extract (7.3.1) to an Erlenmeyer flask (6.4) to which 3 g of anhydrous sodium sulfate (5.5) has been added.
The stopper is shaken several times and allowed to stand. If all of the anhydrous sodium sulfate is agglomerated, anhydrous sodium sulfate (5.5) is added until no more agglomeration.
Note. The extract can also be dewatered through a glass funnel that has been placed with about 10 mm thick anhydrous sodium sulfate (5.5).
7.3.3 Adsorption
Continue to add 3 g of magnesium silicate (5.6) to the extract (7.3.2) and place on the shaker (6.5) at 180 r/min~220.
The r/min speed was oscillated for 20 min and the precipitate was allowed to stand. A small amount of glass wool (5.9) was placed on the bottom of the glass funnel and filtered for testing.
Note. Adsorption can also be carried out using a magnesium silicate adsorption column (5.10). The extract (7.3.2) was passed through a magnesium silicate adsorption column (5.10) and discarded.
2 ml~3 ml of filtrate, to be tested.
7.4 Preparation of blank samples
Replace the sample with experimental water, add hydrochloric acid (5.1) to acidify to pH ≤ 2, according to the preparation of the sample (7.3)
Prepare a blank sample.
8 Analysis steps
8.1 Establishment of the standard curve
Accurately remove 0.00 ml, 0.25 ml, 0.50 ml, 1.00 ml, 2.00 ml and 4.00 ml of petroleum standard solution (5.8)
Dilute to the mark with n-hexane (5.3) in 6 25 ml volumetric flasks and shake well. The standard series concentration is 0.00 mg/L,
41.00 mg/L, 2.00 mg/L, 4.00 mg/L, 8.00 mg/L, and 16.0 mg/L. At a wavelength of 225 nm, use 2 cm
The absorbance was measured using a quartz cuvette with n-hexane (5.3) as a reference. Taking the petroleum concentration (mg/L) as the abscissa,
The corresponding absorbance value is the ordinate and a standard curve is established.
8.2 Determination of samples
The measurement of the sample (7.3) was carried out in accordance with the same procedure as in the establishment of the standard curve (8.1).
Note. When the sample absorbance value is greater than the highest point of the curve, the sample is diluted with n-hexane (5.3) and measured.
8.3 Determination of blank samples
The blank sample (7.4) was measured in the same manner as in the measurement (8.2) of the sample.
9 Calculation and representation of results
9.1 Calculation of results
The mass concentration  (mg/L) of petroleum in water is calculated according to formula (1).
Vb
VaAA
×)--(
= 10 (1)
Where.  - the mass concentration of petroleum in water, mg/L;
A - the absorbance value of the sample;
A0 - the absorbance value of the blank sample;
a -- the intercept of the standard curve;
V1--extract volume, ml;
b -- the slope of the standard curve;
V -- water sample volume, ml.
9.2 Results representation
As a result, the number of decimal places is kept consistent with the detection limit, and up to three significant digits are retained.
10 Precision and accuracy
10.1 Precision
Six laboratories were used to prepare uniform samples at concentrations of 0.05 mg/L, 0.10 mg/L, 0.20 mg/L, and 1.00 mg/L, respectively.
For the determination of the product, the relative standard deviations in the laboratory are. 8.2% to 16%, 5.2% to 7.1%, and 2.2% to 6.8%.
And 0.8% to 2.7%; the relative standard deviations between laboratories are. 14%, 5.8%, 2.8%, and 5.1%;
They are. 0.02 mg/L, 0.01 mg/L, 0.02 mg/L and 0.05 mg/L; the reproducibility limits are. 0.02 mg/L, 0.02 mg/L,
50.02 mg/L and 0.14 mg/L.
10.2 Accuracy
Six laboratories were used to prepare uniform samples at concentrations of 0.05 mg/L, 0.10 mg/L, 0.20 mg/L, and 1.00 mg/L, respectively.
The product is measured, and the relative error ranges are. -20.0% to 0, -10.0% to 0, -10.0% to -5.0%, and -11.0% to 2.0%;
The relative error final values were. (-10.0 ± 22.0)%, (-6.7 ± 10.0)%, (-6.7 ± 5.2)%, and (-4.7 ± 9.6)%, respectively.
11 Quality Assurance and Quality Control
11.1 Blank test
At least one blank test should be performed for each batch of samples, and the test results should be lower than the lower limit of the method.
11.2 Standard curve
The correlation coefficient of the standard curve regression equation should be ≥0.999.
11.3 Accuracy
At least one certified reference material/sample or standard concentration point shall be analyzed for each batch of samples. The relative error of the determination results shall be
Within ±10%. Or at least one sample prepared with certified reference material/sample and laboratory water, the concentration should be the same as the sample
The concentration is similar, and the relative error of the measurement results should be within ±20%.
12 Waste treatment
The waste liquid and waste generated during the experiment should be collected separately and entrusted to qualified units for disposal.
13 Precautions
13.1 Contamination on the wall of the quartz cuvette will affect the results of the measurement. The cleanliness of the quartz cuvette should be checked before each use.
13.2 The hexane used in the preparation of the sample and the blank sample shall be the same batch number.
13.3 Standard oil may be obtained from sources of pollution or contaminated water when conditions permit for the determination of petroleum in such water bodies.
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