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HJ 694-2014

HJ 694-2014_English: PDF (HJ694-2014)
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HJ 694-2014English155 Add to Cart 0--10 minutes. Auto-delivered. Water Quality - Determination of Mercury, Arsenic, Selenium, Bismuth and Antimony - Atomic Fluorescence Spectrometry HJ 694-2014 Valid HJ 694-2014
 

BASIC DATA
Standard ID HJ 694-2014 (HJ694-2014)
Description (Translated English) Water Quality - Determination of Mercury, Arsenic, Selenium, Bismuth and Antimony - Atomic Fluorescence Spectrometry
Sector / Industry Environmental Protection Industry Standard
Classification of Chinese Standard Z16
Word Count Estimation 16,125
Date of Issue 2014/3/13
Date of Implementation 2014/7/1
Quoted Standard GB/T 21191; HJ/T 91; HJ/T 164; HJ 493; HJ 494
Drafting Organization Nanjing Environmental Monitoring Center Station
Administrative Organization Department of Environmental Protection
Regulation (derived from) Ministry of Environmental Protection Notice No. 17 of 2014
Issuing agency(ies) Ministry of Environmental Protection
Summary This Standard specifies the Determination of mercury, arsenic, selenium and antimony secret atomic fluorescence spectrometry. This Standard applies to surface water, groundwater measurement, sewage and industrial waste mercury, arsenic, selenium, antimony

HJ 694-2014
HJ
NATIONAL ENVIRONMENTAL PROTECTION STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
Water Quality - Determination of Mercury, Arsenic,
Selenium, Bismuth and Antimony –
Atomic Fluorescence Spectrometry
ISSUED ON: MARCH 13, 2014
IMPLEMENTED ON: JULY 01, 2014
Issued by: Ministry of Environmental Protection
Table of Contents
Announcement ... 3 
Foreword ... 4 
1 Application scope ... 5 
2 Normative references ... 5 
3 Terms and definitions ... 6 
4 Principle of the method ... 6 
5 Interference and elimination ... 6 
6 Reagents and materials ... 7 
7 Instruments and equipment ... 11 
8 Samples ... 11 
9 Analysis steps ... 12 
10 Result calculation and representation ... 15 
11 Precision and accuracy ... 15 
12 Quality assurance and quality control ... 17 
13 Waste disposal ... 18 
14 Notes ... 18 
Annex A ... 19 
Announcement
2014 No. 17
Ministry of Environmental Protection of the People's Republic of China
To implement the “Environmental Protection Law of the People's Republic of China”,
protect the environment, protect human health, and regulate environmental
monitoring, two standards, including “Water Quality - Determination of Mercury,
Arsenic, Selenium, Bismuth and Antimony - Atomic Fluorescence Spectrometry”, are
approved as national environmental protection standards, and are published.
The standard names and numbers are as follows:
1. “Water Quality - Determination of Mercury, Arsenic, Selenium, Bismuth and
Antimony - Atomic Fluorescence Spectrometry” (HJ 694-2014);
2. “Soil - Determination of organic carbon - Combustion oxidation nondispersive
infrared absorption method” (HJ 695-2014).
Above standards are implemented since July 1, 2014, and are published by China
Environmental Press. The standard content can be inquired at the website of the
Ministry of Environmental Protection (bz.mep.gov.cn).
Notice is hereby given.
Ministry of Environmental Protection
March 13, 2014
Foreword
To implement the “Environmental Protection Law of the People's Republic of China”
and "Water Pollution Prevention Law of the People's Republic of China”, protect the
environment, protect human health, and regulate the monitoring methods of mercury,
arsenic, selenium, antimony, and bismuth in water, this Standard is formulated.
This Standard specifies the atomic fluorescence spectrometry for determination of
mercury, arsenic, selenium, bismuth, and antimony in water.
This Standard is released for the first time.
Annex A of this Standard is informative.
This Standard was formulated by the Department of Science, Technology and
Standards of Ministry of Environment Protection.
Main drafting organization of this Standard: Nanjing Environmental Monitoring Center.
Verification organizations of this Standard: Jiangsu Environment Monitoring Center,
Jiangsu Physical and Chemical Testing Center, Wuxi Environmental Monitoring
Center Station, Changzhou Environmental Monitoring Center, Zhenjiang
Environmental Monitoring Center Station, and Taizhou Environmental Monitoring
Center.
This Standard was approved by the Ministry of Environmental Protection on March 13,
2014.
This Standard shall be implemented from July 1, 2014.
This Standard shall be interpreted by the Ministry of Environmental Protection.
Water Quality - Determination of Mercury, Arsenic,
Selenium, Bismuth and Antimony –
Atomic Fluorescence Spectrometry
Warning: nitric acid, hydrochloric acid, and perchloric acid have a strong
corrosivity and a strong oxidability, so it shall wear protective equipment when
operating, so as to avoid contact with skin and clothing. The pretreatment
process of all samples shall be carried out in a fume hood.
1 Application scope
This Standard specifies the atomic fluorescence spectrometry for the determination of
mercury, arsenic, selenium, bismuth, and antimony in water.
This Standard applies to the determination of soluble [Translator: dissolved-state] and
total quantity of mercury, arsenic, selenium, bismuth, and antimony in surface water,
groundwater, sewage, and industrial waste water.
According to the method of this Standard, the detection limit of mercury is 0.04μg/L,
the determination lower limit of mercury is 0.16μg/L; the detection limit of arsenic is
0.3μg/L, the determination lower limit of arsenic is 1.2μg/L; the detection limit of
selenium is 0.4μg/L, the determination lower limit of selenium is 1.6μg/L; the detection
limit of bismuth and antimony is 0.2μg/L, the determination lower limit of bismuth is
0.8μg/L.
2 Normative references
This Standard references the following documents or its terms. For undated
references, the latest version applies to this Standard.
GB/T 21191 Atomic fluorescence spectrometer
HJ/T 91 Technical specifications requirements for monitoring of surface water
and waste water
HJ/T 164 Technical specifications for environmental monitoring of groundwater
HJ 493 Water quality - Technical regulation of the preservation and handling of
samples
HJ 494 Water quality - Guidance on sampling techniques
3 Terms and definitions
The following terms and definitions apply to this Standard.
3.1
Soluble mercury, arsenic, selenium, bismuth and antimony
It refers to the content of mercury, arsenic, selenium, bismuth, and antimony
determined in the filtrate of the not-acidified sample, after being filtered through the
filter membrane with a pore size of 0.45μg.
3.2
Total quantity of mercury, arsenic, selenium, bismuth and antimony
It refers to the content of mercury, arsenic, selenium, bismuth, and antimony
determined in the unfiltered sample, after being dissolved.
3.3
Determined elements
It refers to mercury, arsenic, selenium, bismuth, and antimony elements.
4 Principle of the method
The test solution after pretreatment is put into the atomic fluorescence spectrometer;
under potassium borohydride (or sodium borohydride)’s reducing effects at acidic
conditions, it generates arsine, bismuthine, antimony hydrogen, hydrogen selenide,
and mercury atoms; the hydride forms ground-state atoms in argon and hydrogen
flames; its ground-state atoms and mercury atoms generate atomic fluorescence by
the excitation of the light emitted by element (mercury, arsenic, selenium, bismuth,
and antimony) lights; the atomic fluorescence intensity is in direct proportion to the
content of determined elements in the sample solution within a certain range.
5 Interference and elimination
5.1 The elements in acidic medium, that can react with potassium borohydride and
generate hydride, would affect each other and produce interference; adding thiourea
+ ascorbic acid solution (6.20) can substantially eliminate the interference.
5.2 Copper and other transition metals that are above a certain concentration may
interfere to the determination; adding thiourea + ascorbic acid solution (6.20) can
eliminate most of the interference. Under the experimental conditions of this Standard,
samples containing less than 100mg/L of Cu2+, less than 50mg/L of Fe2+, less than
1mg/L of Co2+, less than 10mg/L of Pb2+ (5mg/L for selenium), and less than 150mg/L
of Mn2+ (2mg/L for selenium) do not affect the determination.
5.3 Common anions do not interfere to the determination.
5.4 Physical interference elimination. Select two-layer-structure quartz tube atomizer;
with the outer and inner layers filled with argon gas, form a protective outer layer to
isolate air, so that the ground-state atom of determined elements do not collide with
oxygen and nitrogen in the air, so as to reduce the fluorescence quenching effect on
the determination.
6 Reagents and materials
Unless otherwise indicated, use analytically chemical reagents that comply with
national standards when analyzing, water for test is freshly prepared deionized or
distilled water.
6.1 Hydrochloric acid: ρ(HCl) = 1.19g/ml, guarantee reagent.
6.2 Nitric acid: ρ(HNO3) = 1.42g/ml, guarantee reagent.
6.3 Perchloric acid: ρ(HClO4) = 1.68g/ml, guarantee reagent.
6.4 Hydrogen sodium hydride (NaOH).
6.5 Potassium borohydride (KBH4).
6.6 Thiourea (CH4N2S).
6.7 Ascorbic acid (C6H8O6).
6.8 Potassium dichromate (K2Cr2O7): guarantee reagent.
6.9 Mercuric chloride (HgCl2): guarantee reagent.
6.10 Arsenic trioxide (As2O3): guarantee reagent.
6.11 Selenium powder: high-purity (the mass fraction is more than 99.99%).
6.12 Bismuth: high-purity (the mass fraction is more than 99.99%).
6.13 Antimony trioxide (Sb2O3), guarantee reagent.
6.14 Hydrochloric acid solution: 1 + 1.
6.15 Hydrochloric acid solution: 5 + 95.
6.16 Nitric acid solution: 1 + 1.
6.17 Hydrochloric acid - nitric acid solution
Weigh 300ml of hydrochloric acid (6.1) and 100ml of nitrate (6.2) respectively; add to
400ml of water; mix well.
6.18 Mixture acid of nitric acid - perchloric acid
Prepare by mixing an equal volumes of nitric acid (6.2) and perchloric acid (6.3).
Prepare it when it is to be used.
6.19 Reducing agents
6.19.1 Potassium borohydride Solution A
Weigh 0.5g of sodium hydroxide (6.4); dissolve in 100ml of water; add 1.0g of
potassium borohydride (6.5); mix well. This solution is used for the determination of
mercury; prepare it when it is to be used; stored in a plastic bottle.
6.19.2 Potassium borohydride solution B
Weigh 0.5g of sodium hydroxide (6.4); dissolve in 100ml of water; add 2.0g of
potassium borohydride (6.5); mix well. This solution is used for the determination of
arsenic, selenium, bismuth, and antimony; prepare it when it is to be used; stored in a
plastic bottle.
Note: It can also use potassium hydroxide, potassium borohydride to prepare reducing agents.
6.20 Thiourea - ascorbic acid solution
Weigh 5.0g of sulfur urea (6.6) and ascorbic acid (6.7) respectively; dissolve with
100ml of water; mix well. Prepare it at the day of determination.
6.21 Mercury standard solution
6.21.1 Mercury standard fixative
Weigh 0.5g of potassium dichromate (6.8) and dissolve in 950ml of water; add 50ml of
nitric acid (6.2); mix well.
6.21.2 Mercury standard stock solution: ρ(Hg) = 100mg/L.
Purchase the commercially available certified reference materials; or weigh 0.1354g
of mercuric chloride (6.9) that has been placed on a silica dryer overnight; transfer into
a 1000ml flask after dissolved with a small amount of mercury standard fixative
(6.21.1); dilute with mercury standard fixative (6.21.1) to the mark; mix well. Store in a
glass bottle. It can be stored at 4°C for 2 years.
6.21.3 Mercury standard intermediate solution: ρ(Hg) = 1.00mg/L.
Pipette 5.00ml of mercury standard solution (6.21.2) into a 500ml volumetric flask;
add 50ml of hydrochloric acid (6.14); use mercury standard fixative (6.21.1) to dilute to
the mark; mix well. Store in a glass bottle. It can be stored at 4°C for 100 d [Translator:
days].
6.21.4 Mercury standard using solution: ρ(Hg) = 10.0g/L.
Pipette 5.00ml of mercury standard intermediate solution (6.21.3) into a 500ml
volumetric flask; add 50ml of hydrochloric acid (6.14); dilute with water to the mark;
mix well. Store in a glass bottle. Prepare it when it is to be used.
6.22 Arsenic standard solution
6.22.1 Arsenic standard stock solution: ρ(As) = 100mg/L.
Purchase the commercially available certified reference materials; or weigh 0.1320g
of guarantee-reagent arsenic trioxide (6.10) that has been dried at 105°C for 2h;
dissolve in 5ml of 1mol/L sodium hydroxide solution; use 1mol/L hydrochloric acid to
neutralize until phenolphthalein red fades off; transfer into a 1000ml volumetric flask;
dilute with water to the mark; mix well. Store in a glass bottle. It can be stored at 4°C
for 2 years.
6.22.2 Arsenic intermediate standard solution: ρ(As) = 1.00mg/L.
Pipette 5.00ml of arsenic standard stock solution (6.22.1) into a 500ml volumetric
flask; add 100ml of hydrochloric acid (6.14); dilute with water to the mark ; mix well. It
can be stored at 4°C for 1 year.
6.22.3 Arsenic standard using solution: ρ(As) = 100μg/L.
Pipette 10.00ml of arsenic standard intermediate solution (6.22.2) into a 100ml
volumetric flask; add 20ml of hydrochloric acid (6.14); dilute with water to the mark;
mix well. It can be stored at 4°C for 30 d.
6.23 Selenium standard solution
6.23.1 Selenium standard stock solution: ρ(Se) = 100mg/L.
Purchase the commercially available certified reference materials; or weigh 0.1000g
of high-purity selenium powder (6.11) in a 100ml beaker; add 20ml of nitric acid (6.2);
heat at a low temperature to dissolve; cool to room temperature; transfer into a
1000ml volumetric flask; dilute with water to the mark; mix well. Stored in a glass
bottle. It can be stored at 4°C for 2 years.
6.23.2 Selenium standard intermediate solution: ρ(Se) = 1.00mg/L.
Pipette 5.00ml of selenium standard stock solution (6.23.1) into a 500ml volumetric
flask; add 150ml of hydrochloric acid (6.14); dilute with water to the mark; mix well. It
can be stored at 4°C for 100 d.
6.23.3 Selenium standard using solution: ρ(Se) = 10.0μg/L.
Pipette 5.00ml of selenium standard intermediate solution (6.23.2) into a 500ml
volumetric flask; add 150ml of hydrochloric acid (6.14); dilute with water to the mark;
mix well. Prepare it when it is to be used.
6.24 Bismuth standard solution
6.24.1 Bismuth standard stock solution: ρ(Bi) = 100mg/L.
Purchase the commercially available certified reference materials; or weigh 0.1000g
of high-purity mental bismuth (6.12) in a 100ml beaker; add 20ml of nitric acid (6.2);
heat at a low temperature to dissolve completely; cool down; transfer into a 1000ml
volumetric flask; dilute with water to the mark; mix well. Store in a glass bottle. It can
be stored at 4°C for 2 years.
6.24.2 Bismuth standard intermediate solution: ρ(Bi) = 1.00mg/L.
Pipette 5.00ml of bismuth stock standard solution (6.24.1) into a 500ml volumetric
flask; add 100ml of hydrochloric acid (6.14); dilute with water to the mark; mix well. It
can be stored at 4°C for 1 year.
6.24.3 Bismuth standard using solution: ρ(Bi) = 100μg/L.
Pipette 10.00ml of bismuth standard intermediate solution (6.24.2) into a 100ml
volumetric flask; add 20ml of hydrochloric acid (6.14); dilute with water to the mark;
mix well. Prepare it when it is to be used.
6.25 Antimony standard solution
6.25.1 Antimony standard stock solution: ρ(Sb) = 100mg/L.
Purchase the commercially available certified reference materials; or weigh 0.1197g
of antimony trioxide (6.13) that has been dried at 105°C for 2h; dissolve in 80ml of
hydrochloric acid (6.1); transfer into a 1000ml volumetric flask; add 120ml of
hydrochloric acid (6.1); dilute with water to the mark; mix well. Stored in a glass bottle.
It can be stored at 4°C for 2 years.
6.25.2 Antimony standard intermediate solution: ρ(Sb) = 1.00mg/L.
Pipette 5.00ml of antimony standard stock solution (6.25.1) into a 500ml volumetric
flask; add 100ml of hydrochloric acid (6.14); dilute with water to the mark; mix well. It
can be stored at 4°C for 1 year.
6.25.3 Antimony standard using solution: ρ(Sb) = 100μg/L.
Pipette 10.00ml of antimony standard intermediate solution (6.25.2) into a 100ml
volumetric flask; add 20ml of hydrochloric acid (6.14); dilute with water to the mark;
mix well. Prepare it when it is to be used.
6.26 Argon: purity ≥ 99.999%.
7 Instruments and equipment
7.1 Atomic fluorescence spectrometer: Instrument performance indicators shall
comply with specifications of GB/T 21191.
7.2 Element light (mercury, arsenic, selenium, bismuth, antimony).
7.3 Thermostat heating plate.
7.4 Thermostatic water bath device: temperature control accuracy is ±1°C.
7.5 Filtration device: water-system microporous filter membrane with a pore size of
0.45μm.
7.6 Analytical balance: accuracy is 0.0001g.
7.7 Sample container: hard glass bottles or polyethylene bottles (barrels).
7.8 Commonly used laboratory ware: grade-A glass gauges and glassware that
comply with the national standard.
8 Samples
8.1 Sample collection
Sample collection is conducted by referring to the relevant specifications of HJ/T 91
and HJ/T 164. Soluble samples and total quantity samples are collected separately.
8.2 Sample preservation
Sample preservation is conducted by referring to the relevant specifications of HJ
493.
8.2.1 Filterable mercury, arsenic, selenium, bismuth, antimony samples
Filter the sample with 0.45μm filter membrane (7.5) as soon as possible after sample
collection; discard the initial 50ml of filtrate; clean sample bottle with a small amount of
the filtrate; collect the filtrate in the sample bottle. Determine mercury samples; if the
water sample is neutral, add hydrochloric acid in a ratio of adding 5ml of hydrochloric
acid (6.1) per liter of water sample; determine arsenic, selenium, antimony, bismuth
samples; add hydrochloric acid in a ratio of adding 2ml of hydrochloric acid (6.1) per
liter of water sample. Sample preservation period is 14 d.
8.2.2 Total quantity samples of mercury, arsenic, selenium, bismuth, antimony
Except that samples are not filtered after collection, other treatment methods and
preservation period are same as 8.2.1.
8.3 Sample preparation
8.3.1 Mercury
Weigh 5.0ml of mixed sample (8.2.1) or (8.2.2) in a 10ml colorimetric tube; add 1ml of
hydrochloric acid - nitric acid solution (6.17); put on a stopper and mix well; place in
boiling water bath to heat to dissolve for 1h; shake for 1 to 2 times during heating, and
open the stopper to deflate. Cool down; dilute with water to the mark; mix well for test.
8.3.2 Arsenic, selenium, bismuth, antimony
Weigh 50.0ml of mixed sample (8.2.1) or (8.2.2) in a 150ml conical flask; add 5ml of
mixture acid of nitric acid - perchloric acid (6.18); heat on a heating plate until white
smoke emits; cool down. Then add 5ml of hydrochloric acid solution (6.14); heat until
brown smoke disappears; transfer into a 50ml volumetric flask after cooling down;
diluted with water to constant volume; mix well for test.
8.3.3 Blank samples
Use water to replace the sample, prepare blank samples according to the steps of 8.3.
9 Analysis steps
9.1 Instrument adjustment
Adjust the instrument to the optimal working condition according to instrument’s
instructions for use. Reference measurement conditions are shown in Table 1.
Table 1 Reference measurement conditions
Elements
Negative
high
voltage/
Light
current/
mA
Atomizer
preheat
temperature/
°C
Carrier
gas flow/
(ml/min)
Shielding
gas flow/
(ml/min)
Integration
method
Hg 240~280 15~30 200 400 900~1000 Peak area
As 260~300 40~60 200 400 900~1000 Peak area
Se 260~300 80~100 200 400 900~1000 Peak area
Sb 260~300 60~80 200 400 900~1000 Peak area
Bi 260~300 60~80 200 400 900~1000 Peak area
9.2 Calibration
9.2.1 Preparation of calibration standard series
9.2.1.1 Mercury
Pipette respectively 0ml, 1.00ml, 2.00ml, 5.00ml, 7.00ml, 10.00ml of mercury
standard using solution (6.21.4) in 100ml volumetric flasks; add 10.0ml of hydrochloric
acid - nitric acid solution respectively; dilute with water to the mark; mix well.
9.2.1.2 Arsenic
Pipette respectively 0ml, 0.50ml, 1.00ml, 2.00ml, 3.00ml, 5.00ml of arsenic standard
using solution (6.22.3) in 50ml volumetric flasks; add respectively 10ml of hydrochloric
acid solution (6.14) and 10ml of thiourea - ascorbic acid solution (6.20); place at room
temperature for 30min (when room temperature is lower than 15°C, place in 30°C
water bath for 30min); dilute with water to constant volume; mix well.
9.2.1.3 Selenium
Pipette respectively 0ml, 2.00ml, 4.00ml, 6.00ml, 8.00ml, 10.00ml of selenium
standard using solution (6.23.3) in 50ml volumetric flasks; add 10ml of hydrochloric
acid solution (6.14) respectively; dilute with water to constant volume; mix well.
9.2.1.4 Bismuth
Pipette respectively 0ml, 0.50ml, 1.00ml, 2.00ml, 3.00ml, 5.00ml of bismuth standard
using solution (6.24.3) in 50ml volumetric flasks; add 10ml of hydrochloric acid
solution (6.14) respectively; dilute with water to constant volume; mix well.
9.2.1.5 Antimony
Pipette respectively 0ml, 0.50ml, 1.00ml, 2.00ml, 3.00ml, 5.00ml of antimony standard
using solution (6.25.3) in 50ml volumetric flasks; add respectively 10ml of hydrochloric
acid solution (6.14) and 10ml of thiourea - ascorbic acid solution (6.20); place at room
temperature for 30min (when room temperature is lower than 15°C, place in 30°C
water bath for 30min); dilute with water to constant volume; mix well.
Mass concentrations of mercury, arsenic, selenium, bismuth, antimony standard
series are shown in Table 2.
Table 2 Mass concentrations of standard series Unit: μg/L
Elements Mass concentrations of standard series
Hg 0 0.10 0.20 0.50 0.70 1.00
As 0 1.0 2.0 4.0 6.0 10.0
Se 0 0.4 0.8 1.2 1.6 2.0
Bi 0 1.0 2.0 4.0 6.0 10.0
Sb 0 1.0 2.0 4.0 6.0 10.0
9.2.2 Drawing of calibration curves
9.2.2.1 Mercury
Reference to measurement conditions (9.1) or use self-determined optimal
measurement conditions; use hydrochloric acid solution (6.15) as the carrier; use
potassium borohydride solution A (6.19.1) as the reducing agent; determine the
atomic fluorescence intensity of mercury standard series from low to high
concentration; take the atomic fluorescence intensity as ordinate and the mass
concentration of mercury as abscissa, to draw the calibration curve.
9.2.2.2 Arsenic, selenium, bismuth, antimony
Reference to measurement conditions (9.1) or use self-determined optimal
measurement conditions; use hydrochloric acid solution (6.15) as the carrier; use
potassium borohydride solution B (6.19.2) as the reducing agent; determine the
atomic fluorescence intensity of each element standard series from low to high
concentration; take the atomic fluorescence intensity as ordinate and the mass
concentration of the corresponding elements as abscissa, to draw the calibration
curve.
9.3 Sample determination
9.3.1 Mercury
Determine the atomic fluorescence intensity of the sample (8.3.1) according to the
same conditions of drawing calibration curves. For samples that exceed the high
concentration points of the calibration curve, determine again after diluting its
digestion solution, the dilution multiple is f.
9.3.2 Arsenic, antimony
Weigh 5.0ml of sample (8.3.2) in a 10ml colorimetric tube; add 2ml of hydrochloric
acid solution (6.14) and 2ml of thiourea - ascorbic acid solution (6.20); place at room
temperature for 30min (when room temperature is lower than 15°C, place in 30°C
water bath for 30min); dilute with water to constant volume; mix well; determine
according to the same conditions of drawing calibration curves. For samples that
exceed the high concentration points of the calibration curve, determine again after
diluting its digestion solution, the dilution multiple is f.
9.3.3 Selenium, bismuth
Weigh 5.0ml of sample (8.3.2) in a 10ml colorimetric tube; add 2ml of hydrochloric
acid solution (6.14); dilute with water to constant volume; mix well; determine
according to the same conditions of drawing calibration curves. For samples that
exceed the high concentration points of the calibration curve, determine after diluting
its digestion solution, the dilution multiple is f.
9.4 Blank test
Determine the blank sample according to the same procedure of determination (9.2).
10 Result calculation and representation
10.1 Result calculation
The mass concentration ρ of the determined element in the sample is calculated
according to equation (1):
Where:
ρ - The mass concentration of the determined element in the sample, μg/L;
ρ1 - The mas concentration of the determined element in the sample obtained from
the calibration curve, μg/L;
f - Sample dilution multiple (if the sample has been diluted);
V1 - The constant volume of sample after pipetted, ml;
V - The volume of pipetted sample, ml.
10.2 Result presentation
When the determination result of mercury is less than 1μg/L, retain to two decimal
places; when the determination result of mercury is greater than 1μg/L, retain three
significant figures.
When the determination result of arsenic, smashing, bismuth, antimony is less than
10μg/L, retain to one decimal place; when the determination result of arsenic,
smashing, bismuth, antimony is greater than 10μg/L, retain three significant figures.
11 Precision and accuracy
11.1 Precision
Six laboratories have tested the unified sample that contains mercury, arsenic,
selenium, bismuth, antimony of different concentration levels. Test results of method
precision are shown in Table A.1.
Six laboratories have determined the unified sample that contains mercury of four
kinds of concentrations, i.e. 0.10μg/L, 0.20μg/L, 0.40μg/L, and 0.80μg/L. The relative
standard deviations among laboratories are 3.3%~10.9%, 2.0%~7.5%, 1.5%~3.7%,
and 1.5%~2.9% respectively; the relative standard deviations among laboratories are
8.5%, 2.8%, 1.9%, and 1.4%; the repeatability limits are 0.03μg/L, 0.03μg/L, 0.03μg/L,
and 0.05μg/L; the reproducibility limits are 0.03μg/L, 0.03μg/L, 0.04μg/L, and
0.06μg/L.
Six laboratories have determined the unified sample that contains arsenic of three
kinds of concentrations, i.e. 1.0μg/L, 4.0μg/L, and 8.0μg/L. The relative standard
deviations among laboratories are 6.0%~7.0%, 2.3%~5.4%, and 0.9%~3.4%; the
relative standard deviations among laboratories are 4.1%, 1.6%, and 1.5%; the
repeatability limits are 0.2μg/L, 0.4μg/L, and 0.5μg/L; the reproducibility limits are
0.2μg/L, 0.4μg/L, and 0.6μg/L.
Six laboratories have determined the unified sample that contains selenium of three
kinds of concentrations, i.e. 1.0μg/L, 2.0μg/L, and 8.0μg/L. The relative standard
deviations among laboratories are 4.1%~8.9%, 1.2%~4.9%, and 0.3%~3.6%; the
relative standard deviations among laboratories are 4.1%, 2.6%, and 2.7%; the
repeatability limits are 0.2μg/L, 0.2μg/L, and 0.6μg/L; the reproducibility limits are
0.2μg/L, 0.2μg/L, and 0.8μg/L.
Six laboratories have determined the unified sample that contains bismuth of three
kinds of concentrations, i.e. 0.5μg/L, 2.0μg/L, and 4.0μg/L. The relative standard
deviations among laboratories are 4.8%~8.0%, 2.8%~4.7%, and 2.7%~4.0%; the
relative standard deviations among laboratories are 4.5%, 3.6%, and 1.5%; the
repeatability limits are 0.1μg/L, 0.2μg/L, and 0.4μg/L; the reproducibility limits are
0.1μg/L, 0.3μg/L, and 0.4μg/L.
Six laboratories have determined the unified sample that contains mercury of four
kinds of concentrations, i.e. 0.5μg/L, 1.0μg/L, 2.0μg/L, and 4.0μg/L. The relative
standard deviations among laboratories are 6.4%~11.6%, 3.9%~6.7%, 3.2%~4.7%,
and 1.7%~3.8%; the relative standard deviations among laboratories are 4.4%, 4.5%,
2.6%, and 2.7%; the repeatability limits are 0.1g/L, 0.1g/L, 0.2g/L, and 0.3g/L; the
reproducibility limits are 0.1μg/L, 0.2μg/L, 0.2μg/L, and 0.4μg/L.
11.2 Accuracy
Six laboratories have tested the certified reference samples of mercury, arsenic,
selenium of two kinds of concentrations; and conduct spiked recovery test of three
spiked quantity to the unified sample of mercury, arsenic, selenium, bismuth, antimony.
Test data of method accuracy is shown in Table A.2.1 and Table A.2.2 in Annex A.
The relative error of the determination results of mercury’s certified reference
materials (concentration of 16.0μg/L ± 1.4μg/L) by six laboratories is -2.8%~0.9%, the
final value of relative error is -0.4% ± 2.8%; the relative error of the determination
results of mercury’s certified reference materials (concentration of 11.4μg/L ± 1.1μg/L)
is -5.6%~0.0%, the final value of relative error is -3.6% ± 4.0%.
The relative error of the determination results of arsenic’s certified reference materials
(concentration of 60.6μg/L ± 4.2μg/L) by six laboratories is -1.9%~1.7%, the final
value of relative error is -0.4% ± 3.2%; the relative error of the determination results of
arsenic’s certified reference materials (concentration of 75.1μg/L ± 5.3μg/L) is
-4.7%~-0.9%, the final value of relative error is -2.3% ± 3.0%.
The relative error of the determination results of selenium’s certified reference
materials (concentration of 11.2μg/L ± 1.1μg/L) by six laboratories is -1.5%~3.1%, the
final value of relative error is 0% ± 8.8%; the relative error of the determination results
of selenium’s certified reference materials (concentration of 26.2μg/L ± 2.4μg/L) is
-1.5%~3.1%, the final value of relative error is -0.6% ± 3.2%.
Six laboratories have conducted spiked determination to unified industrial waste water,
the spiked quantities of mercury are 0.20μg/L, 0.40μg/L, 0.60μg/L, the spiked
recoveries are 91.5%~104%, 91.2%~99.6%, and 98.6%~107% respectively; the final
values of spiked recovery rates are 98.2% ± 9.4%, 96.6% ± 6.2%, and 102% ± 6.2%
respectively.
Six laboratories have conducted spiked determination to unified industrial waste water,
the spiked quantities of arsenic are 2.0μg/L, 4.0μg/L, 6.0μg/L, the spiked recoveries
are 92.0%~109%, 96.5%~106%, and 94.3%~103% respectively; the final values of
spiked recovery rates are 97.1% ± 12.2%, 100% ± 8.2%, and 99.4% ± 5.8%
respectively.
Six laboratories have conducted spiked determination to unified industrial waste water,
the spiked quantities of selenium are 1.0μg/L, 2.0μg/L, 3.0μg/L, the spiked recoveries
are 90.0%~102%, 96.0%~102%, and 98.7%~107% respectively; the final values of
spiked recovery rates are 95.0% ± 9.4%, 98.2% ± 4.6%, and 102% ± 6.8%.
Six laboratories have conducted spiked determination to unified industrial waste water,
the spiked quantities of bismuth are 1.0μg/L, 2.0μg/L, 4.0μg/L, the spiked recoveries
are 90.0%~103%, 93.5%~104%, and 93.0%~101% respectively; the final values of
spiked recovery rates are 94.8% ± 11.4%, 97.6% ± 7.6%, and 97.0% ± 6.4%.
Six laboratories have conducted spiked determination to unified industrial waste water,
the spiked quantities of antimony are 1.0μg/L, 2.0μg/L, 4.0μg/L, the spiked recoveries
are 94.0%~108%, 92.0%~105%, and 94.0%~100% respectively; the final values of
spiked recovery rates are 101% ± 11.4%, 97.4% ± 10.8%, and 96.2% ± 4.4%.
12 Quality assurance and quality control
12.1 Sampling, storage and management of samples shall be conducted according to
HJ 494 and HJ 493.
12.2 It shall add one determination of laboratory blank, after determinations of 20
samples. It shall determine two laboratory blanks when the batch is less than 20
samples. The determination results of full blank shall be less than the method
detection limit.
12.3 It shall draw calibration curve in each sample analysis. The correlation coefficient
of the calibration curve shall be greater than or equal to 0.995.
12.4 Conduct one verification to the zero-point and mid-point concentration of
calibration curve after determinations of 20 samples, the relative deviation of the test
results shall not exceed 20%.
12.5 Determine at least 10% of parallel double-samples to each batch of samples.
When the sample number is less than 10, determine at least one parallel
double-sample. The relative deviation of the test results shall not be greater than
20%.
12.6 Determine at least 10% of spiked samples to each batch of samples. When the
sample number is less than 10, determine at least one spiked sample. Spiked
recovery rate shall be controlled between 70%~130%.
13 Waste disposal
Waste liquors and waste matters generated in the experiment can not be dumped
at-will, which shall be placed in sealed containers to store, and entrust qualified
organizations to process.
14 Notes
14.1 Potassium borohydride is a strong reducing agent, which is easily to react with
oxygen and carbon dioxide in the air, and easily to decompose and produce hydrogen
in neutral and acidic solutions, therefore, when preparing potassium borohydride
reducing agent, it shall dissolve the solid potassium borohydride in sodium hydroxide
solution, and prepare it when it is to be used.
14.2 Glassware used in laboratory must be soaked in nitric acid solution (6.16) for 24h,
or rinsed with hot nitric acid. When washing, clean with running water and deionized
water successively.
Annex A
(Informative)
Summary table of precision and accuracy
The precision and accuracy data determined by six laboratories are shown in Table
A.1, Table A.2.1, and Table A.2.2.
Table A.1 Method precision
Element
name
Concentration/
(μg/L)
Relative standard
deviation in
laboratory/%
Relative standard
deviation among
laboratories/%
Repeatability
limit r/
(μg/L)
Reproducibility
limit R/(μg/L)
Mercury
0.10 3.3~10.9 8.5 0.03 0.03
0.20 2.0~7.5 2.8 0.03 0.03
0.40 1.5~3.7 1.9 0.03 0.04
0.80 1.5~2.9 1.4 0.05 0.06
Arsenic
1.0 6.0~7.0 4.1 0.2 0.2
4.0 2.3~5.4 1.6 0.4 0.4
8.0 0.9~3.9 1.5 0.5 0.6
Selenium
1.0 4.1~8.9 4.1 0.2 0.2
2.0 1.2~4.9 2.6 0.2 0.2
8.0 0.3~3.6 2.7 0.6 0.8
Bismuth
0.5 4.8~8.0 4.5 0.1 0.1
2.0 2.8~4.7 3.6 0.2 0.3
4.0 2.7~4.0 1.5 0.4 0.4
Antimony
0.5 6.4~11.6 4.4 0.1 0.1
1.0 3.9~6.7 4.5 0.1 0.2
2.0 3.2~4.7 2.6 0.2 0.2
4.0 1.7~3.8 2.7 0.3 0.4
Table A.2.1 Method accuracy (certified reference material test)
Element name Concentration of certified reference material/(μg/L) Relative error/%
Final value of
relative error/%
Mercury 16.0±1.4 -2.8~0.9 -0.4±2.8 11.4±1.1 -5.6~0.0 -3.6±4.0
Arsenic 60.6±4.2 -1.9~1.7 -0.4±3.2 75.1±5.3 -4.7~-0.9 -2.3±3.0
Selenium 11.2±1.1 -5.4~6.2 0.0±8.8 26.2±2.4 -1.5~3.1 0.6±3.2
Table A.2.2 Method accuracy (spiked recovery test)
Element
name
Sample concentration /
(μg/L)
Spiked
concentration /
(μg/L)
Spiked recovery
rate / %
Final value of spiked
recovery rate / %
Mercury
0.39 0.20 91.5~104 98.2±9.4
0.39 0.40 91.2~99.6 96.6±6.2
0.39 0.60 98.6~107 102±6.2
Arsenic
3.9 2.00 92.0~109 97.1±12.2
3.9 4.00 96.5~104 100±8.2
3.9 6.00 94.3~103 99.4±5.8
Selenium
2.0 1.00 90.0~102 95.0±9.4
2.0 2.00 96.0~102 98.2±4.6
2.0 3.00 98.7~107 102±6.8
Bismuth
2.0 1.00 90.0~103 94.8±11.4
2.0 2.00 93.5~104 97.6±7.6
2.0 4.00 93.0~101 97.0±6.4
Antimony
2.0 1.00 94.0~108 101±11.4
2.0 2.00 92.5~105 97.4±10.8
2.0 4.00 94.0~100 96.2±4.4
__________ END __________