Ambient air and stationary source emission - Determination of metals in ambient particulate matter – Inductively coupled plasma/mass spectrometry (ICP-MS), includes Amendment 1
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This standard is formulated with a view to implementing the Environmental Protection Law of the People's Republic of China and the Law of the People's Republic of China on Prevention and Control of Atmospheric Pollution, protecting the environment, guaranteeing human health and standardizing the methods for determining metals in ambient particulate matter.
This standard specifies inductively coupled plasma/mass spectrometry (ICP-MS) for determination of metals in particulate matter from ambient air and fugitive stationary source emission.
This standard hereby is initially issued.
In this standard, Annex A is normative while Annexes B and C are informative.
This standard is organized by the Ministry of Ecology and Environment of the People's Republic of China, Department of Science, Technology and Standard.
This standard was ratified by Ministry of Ecology and Environment of the People's Republic of China on August 16, 2013.
This standard will be implemented as of September 1, 2013.
The Ministry of Environmental Protection of the People's Republic of China is in charge of interpreting this standard.
Ambient air and stationary source emission—Determination of metals in ambient particulate matter—Inductively coupled plasma/mass spectrometry (ICP-MS)
1 Application scope
This standard specifies inductively coupled plasma/mass spectrometry (ICP-MS)for determination of metal elements such as Stibium (Sb), Aluminum (Al), ArSenic (As), Barium (Ba), Beryllium (Be), Cadmium (Cd), Chromium (Cr), Cobalt (Co), Copper (Cu), Plumbum(Pb), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Selenium (Se), Argentum (Ag), Thallium (Tl), Thorium (Th), Uranium (U), Vanadium (V), Zinc (Zn), Bismuth (Bi), Strontium (Sr), Tin (Sn), Lithium (Li), etc.
This standard is applicable to determination of metal elements such as Stibium (Sb), Aluminum (Al), ArSenic (As), Barium (Ba), Beryllium (Be), Cadmium (Cd), Chromium (Cr), Cobalt (Co), Copper (Cu), Plumbum (Pb), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Selenium (Se), Argentum (Ag), Thallium (Tl), Thorium (Th), Uranium (U), Vanadium (V), Zinc (Zn), Bismuth (Bi), Strontium (Sr), Tin (Sn), Lithium (Li) in ambient air PM2.5, PM10, TSP and particulate matter from fugitive stationary source emission.
When the sampling amount of ambient air and stationary source emission is 150m3 (standard state) and 0.600m3 (dry flue gas at standard state), the method detection limit of each metal element is shown in Annex A.
2 Normative references
The following documents contain provisions which, through reference in this standard, constitute provisions of this standard. For undated references, the latest edition applies.
GB/T 16157 The determination of particulates and sampling methods of gaseous pollutants emitted from exhaust gas of stationary source
HJ/T 48 Technical conditions of sampler for stack dust
HJ/T 55 Technical guidelines for fugitive emission monitoring of air pollutants
HJ 77.2 Ambient air and waste gas Determination of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs)
HJ93 Specifications and test procedures for PM10 and PM2.5 sampler
HJ/T 194 Technical specifications on manual methods for ambient air quality monitoring
HJ/T 374 Technical requirement and test procedures for total suspended particulates sampler
HJ/T 397 Technical specifications for emission monitoring of stationary source
Specification for monitoring ambient air quality (on trial (No.4 Announcement [2007] of Ministry of Ecology and Environment of the People's Republic of China)
3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
calibration blank
having composition the same as that of the solution for diluting standards, usually nitric acid solution with concentration (1+99) is used.
3.2
laboratory reagent blank
its preparation must be the same as that of the sample except that the reagent used is the same as that of the sample.
3.3
rinse blank
usually nitric acid solution (2+98) is used, for rinsing residue left in the instrument possibly from the previous determination.
3.4
field blank
such blanks shall be handled and delivered as the actual sample and protected from pollution and loss without drawing ambient air or stationary source emission through the blank filter membrane (cartridge).
4 Method principle
The filter membrane is used to collect particulate matter in ambient air, and the filter cartridge is used to collect particulate matter in stationary source emission. After the collected sample is pretreated (micro wave digestion or electric heating plate digestion), the content of each metal element is determined by inductively coupled plasma mass spectrometer (ICP-MS).
5 Interference and elimination
5.1 Isobaric interference
Table B-1 is an isotope table recommended to avoid such interference (except 98Mo and 82Se which will still be interfered by 98Ru and 82Kr). If other isotopes with larger natural abundance in Table B-1 are selected in order to achieve higher sensitivity, one or more isobaric interferences can be generated. This kind of interference can be corrected by using mathematical equations, usually by measuring another isotope of interfering element, and then subtracting the corresponding signal from the analysis signal. The mathematical equations used must be recorded in the report and verified for their correctness before use.
5.2 Abundance sensitivity
When lots of isotope signals of other elements appear near the isotope of the element to be measured, overlapping peak interference may occur. Such interference, if happens, may be avoided by methods such as improving resolution, matrix separation, using other analysis isotopes or selecting other analysis methods.
5.3 Molecular ion interference
Interfering molecular ions are usually formed in the plasma or interface system by carrier gas or some components in the sample, for example: 40Ar35Cl+ and 98Mo16O+ will interfere with the determination of 75As and 114Cd. The molecular ion interference that has been confirmed by most literatures to affect ICP-MS determination is shown in Table B-2 of Annex B. The correction method for this interference can be obtained by reference to the isotopic abundance in nature, or by adjusting the concentration of standard solution so that the variation coefficient of the net isotopic signal measured by the instrument is less than 1.0%, in order to get interference connection factor (note).
Note 1: The correction coefficient of the instrument can be obtained by conversion of the ratio of the net isotopic signal strength. During its measurement, the isotopic ratio shall be measured with the appropriate concentration of standard solution, and the precision of the measured signal must be less than 1.0%.
5.4 Physical interference
The physical interference is related to the atomization and transmission process of the sample and the ion transmission efficiency. The presence of a large amount of sample matrix will cause the change of surface tension or viscosity of the sample solution, thus changing the atomization and transmission efficiency of the sample solution, and inhibiting or increasing the appearance of analysis signals. In addition, a large amount of dissolved solids in the sample solution deposited in the atomizer nozzle and sampling cone cavity will also reduce the strength of the analysis signal. Therefore, the total dissolved solids content in the sample solution must be less than 0.2% (2000mg/L). Due to the same degree of change between the internal standard and the element to be measured when physical interference occurs, the physical interference can be corrected by adding the internal standard. When the concentration of matrix in the sample is too high and the signal of internal standard is significantly inhibited (less than 30% of the normal signal value), the sample solution can be re-measured after proper dilution to avoid physical interference.
5.5 Memory interference
In the continuous determination of samples or standards with large concentration differences, the deposition and retention of the elements to be measured in the samples on the vacuum interface, spray chamber and atomizer will lead to memory interference, which can be avoided by prolonging washing time before and after the sample determination.
6 Reagents and materials
Unless otherwise specified, the chemical reagents shall be guaranteed reagent or higher level conforming to national standards for analysis. The experimental water is ultrapure water with a specific resistance at least 18MΩ·cm.
6.1 Nitric acid: ρ (HNO3)=1.42g/ml.
Guaranteed reagent or high purity (e.g. microelectronic grade).
6.2 Hydrochloric acid: ρ (HCl)=1.19g/ml.
Guaranteed reagent or high purity (e.g. microelectronic grade).
6.3 Nitric acid-hydrochloric acid solution
Add 55.5ml of nitric acid (6.1) and 167.5 ml of hydrochloric acid (6.2) into about 500ml of ultrapure water, and dilute it to 1L with ultrapure water.
6.4 Standard solution
6.4.1 Single element standard stock solution: ρ=1.00mg/ml.
It can be prepared with high purity metals (>99.99%) or metallic salts (reference or high purity reagents), and its acidity is maintained above 1.0% (v/v). It is also allowed to buy certified standard solutions.
6.4.2 Multi-element standard stock solution: ρ = 100 mg/l.
It may be prepared by single element standard stock solution or buy certified standard solution directly.
6.4.3 The multi-element standard solution
The concentration of is suggested to be ρ = 200μg/L.
6.4.4 Internal standard stock solution
The internal standard element shall be selected according to the mass number of isotope of the element to be tested, which is generally within the mass number of ±50amu. The recommended internal standard elements are shown in Table B-3 of Annex B. It can be certified standard solution or prepared by high purity metal (>99.99%) or appropriate metal salts (reference or high purity reagents). The concentration is prepared to be 100.0μg/L and the medium is 1% nitric acid.
6.4.5 Mass spectrometer tuning solution
The recommended concentration is ρ = 100μg/L. The solution should contain enough ions to cover the full mass spectrum range, including Li, Be, Mg, Co, In, Tl, Pb, etc. It can be certified standard solution or prepared by high purity metal (>99.99%) or appropriate metal salts (reference or high purity reagents).
6.5 Glass fiber or quartz filter membrane
It has a retention efficiency of at least 99% if particle size is greater than 0.3μm; the background concentration value shall meet the determination requirements.
6.6 Glass fiber or quartz cartridge
It has a retention efficiency of at least 99.9% if particle size is greater than 0.3μm; the background concentration value shall meet the determination requirements.
6.7 Argon
Its purity is at least 99.99%.
7 Apparatus
7.1 Cutter
7.1.1 TSP cutter: The cutting particle size Da50=(100±0.5)μm. Other performance and technical indexes shall conform to the provisions of HJ/T 374.
7.1.2 PM10 cutter: The cutting particle size Da50=(10±0.5)μm; the geometric standard deviation of capture efficiency σg=(1.5±0.1)μm. Other performance and technical indexes shall conform to the provisions of HJ/T 93.
7.1.3 PM2.5 cutter: The cutting particle size Da50=(2.5±0.2)μm; the geometric standard deviation of capture efficiency σg=(1.2±0.1)μm. Other performance and technical indexes shall conform to the provisions of HJ/T 93.
7.2 Particulate sampler
7.2.1 Ambient air (fugitive emission) sampling equipment
For high-flow sampler: the working point flow of the sampler is 1.05m3/min.
For medium-flow sampler: the working point flow of the sampler is 0.100m3/min.
Other performance and technical indexes of high-flow and medium-flow samplers shall conform to the provisions of HJ/T 374.
7.2.2 Sampling equipment of stationary source emission
For smoke sampler: sampling flow rate is (5 ~ 80) L/min, and other performance and technical indexes shall conform to the provisions of HJ/T 48.
7.3 Inductively coupled plasma mass spectrometer
Its mass range is (5~250)amu and the minimum width is 1amu when the resolution is at 5% of wave peak.
7.4 Microwave digestion device
7.4.1 Microwave digestion device: with programmable power setting function, enabling to provide an output power of 600W.
7.4.2 Microwave digestion receptacle: PFA Teflon or equivalent material.
7.4.3 Rotating disk: During microwave digestion, rotating disk must be used to ensure the uniformity of the sample subjecting to microwave.
7.5 Electric heating plate: 100℃.
7.6 Ceramic scissors.
7.7 Teflon beaker: 100ml.
7.8 Polyethylene volumetric flask: 50ml, 100ml.
7.9 Polyethylene or polypropylene flask: 100ml.
7.10 Grade A glass gauge.
7.11 Common apparatuses used in general laboratories.
8 Samples
8.1 Collection and preservation
8.1.1 Sample collection
8.1.1.1 Ambient air sample
The setting of ambient air sampling points shall conform to the relevant requirements in the Specification for monitoring ambient air quality (on trial). The sampling process is carried out in accordance with HJ/T 194 for particulate matter sampling. The volume of ambient air sample collected shall not be less than 10m3 in principle. When the concentration of heavy metals is low or PM10 (PM2.5) samples are collected, the collection volume may be appropriately increased. Record the sampling conditions in detail while sampling.
8.1.1.2 Fugitive emission sample
Monitoring points shall be set for fugitive emission sample collection according to relevant requirements in HJ/T 55, and other requirements shall be the same as those for ambient air sample collection.
8.1.1.3 Stationary source emission sample
The sampling process of stationary source emission shall be carried out in accordance with the requirements of GB/T 16157 for particulate matter sampling. For particulate matter sampling using smoke sampler, the volume is not less than 0.600m3 (dry flue gas in standard state) in principle. When the concentration of heavy metals is low, the volume of gas collected may be appropriately increased.
If the temperature of flue gas in the pipeline is higher than the melting point of relevant metal elements to be collected, cooling measures shall be taken so that the temperature of flue gas, before entering the filter cartridge, is lower than the melting point of relevant metal elements. For specific methods, please refer to HJ/T 77.2.
8.1.2 Preservation of samples
After collecting the filter membrane sample, fold the dust surface inward twice and put it into a sample box or paper bag. After collecting the filter cartridge sample, fold the seal inward and put it back into the original sampling cartridge in a sealed state.
Before analysis, the samples are stored at (15~30)℃ for a maximum period of 180 days.
8.2 Specimen preparation
8.2.1 Microwave digestion
Take appropriate amount of filter membrane samples: 1/8 of a large piece of TSP filter membrane (with a size of about 20cm×25cm) and a whole piece of small circular filter membrane (with a diameter of 90mm or less). Cut into small pieces with ceramic scissors and place them in the digestion tank, add 10.0ml nitric acid-hydrochloric acid solution (6.3), immerse the filter membrane into it, cover and place it in the digestion tank assembly, screw it tightly, and place on the microwave disk holder. Set the digestion temperature at 200℃ and the digestion duration at 15 minutes before starting digestion. After digestion, take out the digestion tank assembly before cooling down, rinse the inner wall with ultra-pure water, and then add about 10ml of ultra-pure water, stand for half an hour. After digesting and filtering, dilute the volume to 50.0ml for determination. Alternatively, the volume can be diluted to 50.0ml, and the supernatant can be taken for determination after centrifugal separation.
Note 2: Take a whole filter cartridge sample, cut it into small pieces, add 25.0ml nitric acid-hydrochloric acid solution (6.3) to immerse the filter cartridge, and finally fix the volume to 100.0ml. Other operations are the same as the filter cartridge sample. If the sample size of the filter membrane is large, the volume of nitric acid-hydrochloric acid solution (6.3) can be appropriately increased to immerse the filter membrane therein.
8.2.2 Digestion using electric heating plate
Take appropriate amount of filter membrane samples: 1/8 of a large piece of TSP filter membrane (with a size of about 20cm×25cm) and a whole piece of small circular filter membrane (with a diameter of 90mm or less). Cut into small pieces with ceramic scissors and place them in a Teflon beaker. Add 10.0ml nitric acid-hydrochloric acid solution (6.3) to immerse the filter membrane in it, cover the watch glasses, heat and reflux at 100℃ for 2.0 hours, and then cool it down. Rinse the inner wall of the beaker with ultra-pure water, add about 10ml of ultra-pure water, let stand for half an hour. After digesting and filtering, dilute the volume to 50.0ml for determination. Alternatively, the volume can be diluted to 50.0ml, and the supernatant can be taken for determination after centrifugal separation.
Note 3: Take a whole filter cartridge sample, add 25.0ml nitric acid-hydrochloric acid solution (6.3) and finally fix the volume to 100.0ml. Other operations are the same as the filter cartridge sample. If the sample size of the filter membrane is large, the volume of nitric acid-hydrochloric acid solution (6.3) can be appropriately increased to immerse the filter membrane therein.
9 Analytical procedures
9.1 Apparatus tuning
After igniting the plasma, the apparatus needs to be preheated and stabilized for 30 minutes. During this period, mass correction and resolution verification can be performed with the mass spectrometer tuning solution. The mass spectrometer tuning solution must be measured at least 4 times to confirm the relative standard deviation (RSD) of the signal strength of the elements contained in the measured turning solution is not higher than 5%. Mass correction and resolution verification must be carried out for the mass number range covered by the elements to be measured. If the difference between the correction result and the real value is more than 0.1amu, the mass must be corrected to the correct value according to the apparatus instruction. The width is about 1amu when resolution of the analysis signal is at 5% of the peak height.
9.2 Plotting of calibration curve
Prepare a series of standard solutions of elements to be tested successively in volumetric flask with concentrations of 0μg/L, 0.100μg/L, 0.500μg/L, 1.00μg/L, 5.00μg/L, 10.0μg/L, 50.0μg/L, 100.0μg/L and the medium is 1% nitric acid. The internal standard solution (6.4.4) can be directly added into each sample, or can be added with another peristaltic pump before sample atomization, so as to be fully mixed with the sample. Determine with ICP-MS and plot calibration curve. The concentration range of the calibration curve can be adjusted according to the measurement requirements.
9.3 Sample determination
Before determining each sample, rinse the system with rinse blank until the signal is minimized (usually 30 seconds), and then start the determination after the signal is stabilized (usually 30 seconds). The internal standard solution (6.4.4) shall be added during sample determination. If the concentration of the element to be measured in the sample exceeds the calibration curve range, it shall be determined again after dilution.
In order to reduce the damage of vacuum interface and the interference of multi-atom ions of the same weight, the concentration of acid in sample solution must be controlled within 2%. In addition, when hydrochloric acid is contained in the sample solution, the interference of multi-atom ions can be corrected by the correction equation listed in Table B-4 of Annex B or by means of reaction cell technology, etc.
9.4 Blank experiment
The blank test is made using ultrapure water instead of sample. The test is made by exactly the same preparation and determination method as the sample, and the same reagent amount. A blank experiment is carried out while measuring the sample, and that is the laboratory reagent blank.
10 Result calculation and expression
10.1 Refer to Table B-4 for recommended correction equations for each element.
10.2 Result calculation
The concentration of metal elements in particulate matter is calculated as follows:
Where:
ρm——the mass concentration of metal elements in particulate matter, μg/m3;
ρ——The concentration of metal elements in the sample, μg/L;
V——the sample volume after sample digestion, ml;
n——the number of pieces into which the filter paper is cut. If it is a small circular filter membrane or filter cartridge, take the whole piece during digestion, then n = 1; if it is a large filter membrane, take one eighth when digestion, then n = 8;
Fm——the average metal content of blank filter membrane (filter cartridge), μg. For a large number of filter membranes (filter cylinder), 20 ~ 30 pieces can be randomly selected for determination to calculate the average concentration; for small batch filter membrane (filter cartridge), a small number (5%) may be selected for the determination.
Vstd——the sample Volume in standard state (273K, 101.325Pa), m3. For samples from stationary source emission, Vstd is the sampling volume of dry flue gas in standard state, m3.
10.3 Expression of results
The final result is accurate to three significant digits.
Foreword i
1 Application scope
2 Normative references
3 Terms and definitions
4 Method principle
5 Interference and elimination
6 Reagents and materials
7 Apparatus
8 Samples
9 Analytical procedures
10 Result calculation and expression
11 Precision and accuracy
12 Quality assurance and control
13 Disposal of waste
14 Cautions
Annex A (Informative)
Annex B (Informative)
Annex c Informative Microwave power correction method
