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HJ 491-2019 (HJ491-2019)

HJ 491-2019_English: PDF (HJ491-2019)
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BASIC DATA
Standard ID HJ 491-2019 (HJ491-2019)
Description (Translated English) Soil and sediment - Determination of copper, zinc, lead, nickel and chromium - Flame atomic absorption spectrophotometry
Sector / Industry Environmental Protection Industry Standard
Classification of Chinese Standard Z18
Classification of International Standard 13.080
Word Count Estimation 15,135
Date of Issue 2019
Date of Implementation 2019-09-01

Standards related to: HJ 491-2019

HJ 491-2019
HJ
NATIONAL ENVIRONMENTAL PROTECTION STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
Replacing HJ 491-2009
Soil and sediment - Determination of copper, zinc, lead,
nickel and chromium - Flame atomic absorption
spectrophotometry
ISSUED ON: MAY 12, 2019
IMPLEMENTED ON: SEPTEMBER 01, 2019
Issued by: Ministry of Ecology and Environment
Soil and sediment - Determination of copper, zinc, lead,
nickel and chromium - Flame atomic absorption
spectrophotometry
Warning: Since the perchloric acid and nitric acid used in the experiment are
highly oxidizing and corrosive, and the hydrochloric acid and hydrofluoric acid
are highly volatile and highly corrosive, reagent preparation and sample digestion
shall be carried out in a fume hood; during the operation, protective equipment
shall be wore as required to avoid inhalation into respiratory tract or contact with
skin and clothing.
1 Scope of application
This Standard specifies the flame atomic absorption spectrophotometry for the
determination of copper, zinc, lead, nickel and chromium in soil and sediment.
This Standard applies to the determination of copper, zinc, lead, nickel and chromium
in soil and sediment.
When the sample volume is 0.2 g and the constant volume after digestion is 25 ml, the
method detection limits for copper, zinc, lead, nickel and chromium are 1 mg/kg, 1
mg/kg, 10 mg/kg, 3 mg/kg and 4 mg/kg, respectively, and the lower limits of
determination are 4 mg/kg, 4 mg/kg, 40 mg/kg, 12 mg/kg and 16 mg/kg, respectively.
2 Normative references
This standard refers to the following documents or clauses therein. For undated
references, the valid edition applies to this Standard.
GB 17378.3, The specification for marine monitoring - Part 3: Sample collection
storage and transportation
GB 17378.5, The specification for marine monitoring - Part 5: Sediment analysis
HJ 494, Water quality - Guidance on sampling techniques
HJ 613, Soil - Determination of dry matter and water content - Gravimetric method
HJ 832, Soil and sediment - Digestion of total metal elements - Microwave assisted
acid digestion method
HJ/T 166, Technical specification for soil environmental monitoring
3 Principle of the method
After the soil and sediment are digested by acid, the copper, zinc, lead, nickel and
chromium in the sample are atomized in the air-acetylene flame, and the ground state
atoms have selective absorption of the characteristic spectral lines of copper, zinc, lead,
nickel and chromium respectively; the absorption intensity is proportional to the
concentration of copper, zinc, lead, nickel and chromium within a certain range.
4 Interference and elimination
4.1 Iron below 1 000 mg/L does not interfere with the determination of zinc.
4.2 Potassium, sodium, magnesium, iron and aluminum below 2 000 mg/L, as well as
calcium below 1 000 mg/L, do not interfere with the determination of lead.
4.3 When using 232.0 nm as the absorption line to measure nickel, it is influenced by
the nickel three-line spectrum of similar wavelength, and the selection of 0.2 nm
spectral passband can reduce the influence.
4.4 Under the conditions of this Standard, when using a reducing flame, the common
elements coexisting in soil and sediment do not interfere with the determination of
chromium.
5 Reagents and materials
Unless otherwise stated, use guaranteed reagents that meet national standards in the
analysis, and use freshly prepared deionized water as the experimental water.
5.1 Hydrochloric acid: ρ(HCl) = 1.19 g/ml.
5.2 Nitric acid: ρ(HNO3) = 1.42 g/ml.
5.3 Hydrofluoric acid: ρ(HF) = 1.49 g/ml.
5.4 Perchloric acid: ρ(HClO4) = 1.68 g/ml.
5.5 Metal copper: spectral pure.
5.6 Metal zinc: spectral pure.
5.7 Metal lead: spectral pure.
5.8 Metal nickel: spectral pure.
5.9 Metal chromium: spectral pure.
Accurately pipette 10.00 ml of zinc standard stock solution (5.14) into a 100 ml
volumetric flask; use nitric acid solution (5.12) to dilute to the mark; shake well. Store
in a polyethylene bottle; refrigerate below 4 ℃, valid for one year.
5.20 Lead standard working solution: ρ(Pb) = 100 mg/L.
Accurately pipette 10.00 ml of lead standard stock solution (5.15) into a 100 ml
volumetric flask; use nitric acid solution (5.12) to dilute to the mark; shake well. Store
in a polyethylene bottle; refrigerate below 4 ℃, valid for one year.
5.21 Nickel standard working solution: ρ(Ni) = 100 mg/L.
Accurately pipette 10.00 ml of nickel standard stock solution (5.16) into a 100 ml
volumetric flask; use nitric acid solution (5.12) to dilute to the mark; shake well. Store
in a polyethylene bottle; refrigerate below 4 ℃, valid for one year.
5.22 Chromium standard working solution: ρ(Cr) = 100 mg/L.
Accurately pipette 10.00 ml of chromium standard stock solution (5.17) into a 100 ml
volumetric flask; use nitric acid solution (5.12) to dilute to the mark; shake well. Store
in a polyethylene bottle; refrigerate below 4 ℃, valid for one year.
5.23 Gas: acetylene, purity ≥99.5%.
5.24 Supporting gas: air, where water, oil and other impurities shall be removed before
entering the burner.
6 Instruments and apparatuses
6.1 Flame atomic absorption spectrophotometer.
6.2 Light source: sharp line source or continuous light source of copper, zinc, lead,
nickel and chromium elements.
6.3 Electrothermal digestion device: temperature-controlled electric heating plate or
graphite electrothermal digestion instrument, with a temperature control accuracy of
±5 °C.
6.4 Microwave digestion device: power 600 W ~ 1 500 W, equipped with microwave
digestion tank.
6.5 Polytetrafluoroethylene crucible or polytetrafluoroethylene digestion tube: 50 ml.
6.6 Analytical balance: sensitivity 0.1 mg.
6.7 Utensils and equipment commonly used in general laboratories.
7 Sample
7.1 Sample collection and storage
Soil samples shall be collected and stored in accordance with the relevant requirements
of HJ/T 166; sediment samples shall be collected and stored in accordance with the
relevant requirements of GB 17378.3 or HJ 494.
7.2 Sample preparation
Remove foreign matter (such as sticks, leaves, stones) in the sample; in accordance with
the requirements of HJ/T 166 and GB 17378.3, air-dry, crush, and sieve the collected
samples in the laboratory, and save them for future use.
7.3 Determination of moisture
Measure the dry matter content of soil samples according to HJ 613; determine the
moisture content of sediment samples according to GB 17378.5.
7.4 Preparation of test pieces
7.4.1 Electrothermal digestion method
7.4.1.1 Hot plate digestion method
Weigh 0.2 g ~ 0.3 g (accurate to 0.1 mg) of the sample (7.2) into a 50 ml
polytetrafluoroethylene crucible (6.5); use water to wet it; then, add 10 ml of
hydrochloric acid (5.1); put it on the electric heating plate in the fume hood at 90 ℃ ~
100°C to decompose the sample initially; when the digestion solution evaporates to
about 3 ml remaining, add 9 ml of nitric acid (5.2); cover and heat until there are no
obvious particles; add 5 ml ~ 8 ml of hydrofluoric acid (5.3); uncover the lid; heat to
remove silicon at 200 ℃ for 30 minutes; cool slightly; add 1 ml of perchloric acid (5.4);
heat at 150 ℃ ~ 170 ℃ until white smoke comes out; shake the crucible frequently
during heating. If there are black carbides on the crucible wall, add 1 ml of perchloric
acid (5.4); cover and continue to heat until the black carbides disappear; then, uncover;
heat to remove the acid until the contents are in the shape of liquid beads that do not
flow (observe while it is hot). Add 3 ml of nitric acid solution (5.12); warm to dissolve
the soluble residue; transfer the entire amount to a 25 ml volumetric flask; use nitric
acid solution (5.12) to dilute to the mark; shake well; store in a polyethylene bottle; let
stand; take the supernatant liquid for later testing. Complete the analysis within 30 days.
7.4.1.2 Graphite electrothermal digestion method
Weigh 0.2 g ~ 0.3 g (accurate to 0.1 mg) of the sample (7.2) into a 50 ml
polytetrafluoroethylene digestion tube (6.5); use water to wet it; then, add 5 ml
hydrochloric acid (5.1); put it on the graphite electrothermal digestion instrument in the
fume hood to heat at 100 °C for 45 min. Add 9 ml of nitric acid (5.2) and heat for 30
wH2O – moisture content of the sediment sample, %.
9.3 Result expression
When the measurement result is less than 100 mg/kg, keep the result to an integer; when
the measurement result is greater than or equal to 100 mg/kg, keep the result to three
significant figures.
10 Precision and accuracy
10.1 Precision
Six laboratories shall respectively perform six repeated determinations on the uniform
samples of yellow soil with copper content of 22 mg/kg, brown soil of 106 mg/kg, river
sediment of 16 mg/kg and lake sediment of 63 mg/kg, where the intra-laboratory
relative standard deviation ranges are 1.4% ~ 4.0%, 1.6% ~ 3.9%, 1.1% ~ 6.7% and
1.0% ~ 3.0%, respectively; the inter-laboratory relative standard deviation ranges are
3.7%, 2.3%, 4.0% and 3.0%, respectively; the repeatability limits r are 2 mg/kg, 8
mg/kg, 2 mg/kg and 4 mg/kg, respectively; the reproducibility limits R are 3 mg/kg, 10
mg/kg, 3 mg/kg and 7 mg/kg, respectively.
Six laboratories shall respectively perform six repeated determinations on the uniform
samples of yellow soil with zinc content of 49 mg/kg, brown soil of 165 mg/kg, river
sediment of 61 mg/kg and lake sediment of 190 mg/kg, where the intra-laboratory
relative standard deviation ranges are 1.0% ~ 3.5%, 1.1% ~ 3.6%, 1.1% ~ 3.8% and
1.3% ~ 4.5%, respectively; the inter-laboratory relative standard deviation ranges are
3.2%, 4.7%, 4.0% and 4.3%, respectively; the repeatability limits r are 4 mg/kg, 11
mg/kg, 5 mg/kg and 15 mg/kg, respectively; the reproducibility limits R are 6 mg/kg,
24 mg/kg, 8 mg/kg and 27 mg/kg, respectively.
Six laboratories shall perform six repeated measurements on the certified standard
samples GSS-5 and GSD-5a, as well as the uniform samples of brown soil with a lead
content of 116 mg/kg, and river sediment with a lead content of 152 mg/kg, where the
intra-laboratory relative standard deviation ranges are 1.8% ~ 4.7%, 0.7% ~ 3.1%, 2.9%
~ 6.5% and 2.1% ~ 6.4%, respectively; the inter-laboratory relative standard deviations
are 1.3%, 2.0%, 5.4% and 3.1% respectively; the repeatability limits r are 48 mg/kg, 6
mg/kg, 16 mg/kg and 16 mg/kg, respectively; the reproducibility limits R are 49 mg/kg,
8 mg/kg, 23 mg/kg and 20 mg/kg, respectively.
Six laboratories shall respectively perform six repeated determinations on the uniform
samples of yellow soil with nickel content of 24 mg/kg, brown soil of 35 mg/kg, river
sediment of 20 mg/kg and lake sediment of 36 mg/kg, where the intra-laboratory
relative standard deviation ranges are 1.8% ~ 7.0%, 1.9% ~ 4.0%, 2.2% ~ 8.1% and
2.1% ~ 6.7%, respectively; the inter-laboratory relative standard deviation ranges are
3.4%, 2.9%, 4.2% and 3.7%, respectively; the repeatability limits r are 3 mg/kg, 3
mg/kg and 42 mg/kg: the additional-standard recovery ranges are 88.9% ~ 105% and
92.7% ~ 98.5% respectively; the additional-standard recovery final values are
96.9%±12.4% and 95.5%±4.2%, respectively. Six laboratories shall respectively
conduct six repeated measurements on the river sediment sample with copper content
of 16 mg/kg – with additional-standard amount of 17 mg/kg and 42 mg/kg: the
additional-standard recovery ranges are 87.4% ~ 100% and 91.1% ~ 102%, respectively;
the additional-standard recovery final values are 94.3%±9.0% and 96.0%±9.0%,
respectively.
Six laboratories shall respectively conduct six repeated measurements on the yellow
soil sample with zinc content of 49 mg/kg – with additional-standard amount of 17
mg/kg and 42 mg/kg: the additional-standard recovery ranges are 90.5% ~ 108% and
86.7% ~ 104%, respectively; the additional-standard recovery final values are
98.1%±13.8% and 95.4%±12.6%, respectively. Six laboratories shall respectively
conduct six repeated measurements on the river sediment samples with zinc content of
61 mg/kg – with additional-standard amount of 17 mg/kg and 42 mg/kg: the additional-
standard recovery ranges are 88.7% ~ 102% and 90.0% ~ 109% respectively; the
additional-standard recovery final values are 96.2%±9.8% and 98.4%±14.2%,
respectively.
Six laboratories shall respectively conduct six repeated measurements on the brown soil
samples with lead content of 116 mg/kg – with additional-standard amount of 125
mg/kg and 250 mg/kg: the additional-standard recovery ranges are 90.3% ~ 104% and
94.1% ~ 99.8% respectively; the additional-standard recovery final values are
97.5%±10.2% and 97.5%±5.2%, respectively. Six laboratories shall respectively
conduct six repeated measurements on the river sediment sample with lead content of
152 mg/kg – with additional-standard amount of 83 mg/kg and 167 mg/kg: the
additional-standard recovery ranges are 87.2% ~ 106% and 84.7% ~ 101%, respectively;
the additional-standard recovery final values are 92.8%±8.2% and 92.5%±12.6%,
respectively.
Six laboratories shall respectively conduct six repeated measurements on the yellow
soil sample with nickel content of 24 mg/kg – with additional-standard amount of 17
mg/kg and 42 mg/kg: the additional-standard recovery ranges are 87.6% ~ 100% and
93.6% ~ 100%, respectively; the additional-standard recovery final values are
95.9%±10.4% and 97.6%±5.0%, respectively. Six laboratories shall respectively
conduct six repeated measurements on the river sediment samples with nickel content
of 20 mg/kg – with additional-standard amount of 17 mg/kg and 42 mg/kg: the
additional-standard recovery ranges are 91.5% ~ 101% and 84.9% ~ 104% respectively;
the additional-standard recovery final values are 97.7%±7.0% and 95.0%±13.6%,
respectively.
Six laboratories shall respectively conduct six repeated measurements on the yellow
soil sample with chromium content of 68 mg/kg – with additional-standard amount of
17 mg/kg and 42 mg/kg: the additional-standard recovery ranges are 89.2% ~ 105%
and 90.8% ~ 104%, respectively; the additional-standard recovery final values are
96.9%±11.4% and 96.1%±9.6%, respectively. Six laboratories shall respectively
conduct six repeated measurements on the river sediment samples with chromium
content of 60 mg/kg – with additional-standard amount of 17 mg/kg and 42 mg/kg: the
additional-standard recovery ranges are 92.0% ~ 102% and 88.8% ~ 109% respectively;
the additional-standard recovery final values are 98.5%±7.6% and 96.2%±19.6%,
respectively.
See Appendix A for accuracy data.
11 Quality assurance and quality control
11.1 Make at least 2 laboratory blanks for each batch of samples. The determination
result of zinc in the blank shall be lower than the lower detection limit, and the
determination results of other elements shall be lower than the detection limit of the
method.
11.2 A standard curve shall be established for each analysis, and its correlation
coefficient shall be ≥0.999.
11.3 After the analysis of every 20 samples or each batch (less than 20 samples/batch),
it is necessary to check the zero-concentration point and intermediate concentration
point of the standard series. The measurement result at the zero-concentration point
shall be lower than the detection limit of the method, and the relative error between the
measured value of the intermediate concentration and the standard value shall be within
±10%.
11.4 For every 20 samples or each batch (less than 20 samples/batch), a parallel sample
shall be analyzed, and the relative deviation of the parallel sample determination results
shall be ≤20%.
11.5 For every 20 samples or every batch (less than 20 samples/batch), one certified
standard sample shall be measured at the same time, and the relative error between the
measurement result and the guaranteed value shall be within ±15%; alternatively, for
every 20 samples or each batch (less than 20 samples/batch), one substrate additional-
standard sample shall be analyzed, and the additional-standard recovery rate shall be
80% ~ 120%.
12 Waste disposal
The waste generated in the experiment shall be classified and collected, marked
accordingly, and entrusted to a qualified unit for disposal.
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