HJ 777-2015Ambient air and waste gas from stationary sources emission. Determination of metal elements in ambient particle matter. Inductively coupled plasma optical emission spectrometry (English PDF)

4.1 Spectral interference

Spectral disturbances mainly include continuous background and overlapping lines. The usual method of correcting spectral interference is the background subtraction method (According to the single element test to determine the location and manner of subtracting the background) and the interference coefficient method. It can also be mixed in standard solutions Using matrix matching method to eliminate its impact.

When there is a single element interference, the interference factor can be obtained according to the following formula.

Where. tK - interference coefficient;

'Q - interference element plus analysis element content;

Q - analysis of the content of elements;

TQ - the content of interfering elements.

The Q & apos; was determined at the position of the wavelength of the analytical element by preparing a series of solutions of known interfering element content, Formula to find tK, and then artificial deduction or computer automatically deducted.

Under normal circumstances, the atmospheric particulate matter in the concentration of each element is low, the interference between the spectral and matrix elements can be ignored slightly. Pollutants Particulate matter Common Target Metal Element Determination Wavelength Spectral interference and its interference coefficient Reference values are given in Appendix C.

Note that the interferometric coefficients for different instruments are different.

4.2 Non-spectral interference

Non-spectral interference mainly includes chemical interference, ionization interference, physical interference and solvent interference, etc., in the actual analysis the process of interference is difficult to completely separate. Whether it is compensated and corrected, and the concentration of interfering elements in the sample. this , The physical interference is generally caused by the viscosity of the sample and the surface tension changes, especially when the sample contains a large number of soluble Salt, the measurement may interfere. The easiest way to eliminate such interference is to dilute the sample.

6.1 Particulate Sampler

The use of ambient air particulate samplers (including cutter) performance and technical specifications should be consistent with HJ/T 374 and HJ 93 Regulations. The sampling flow rate of the waste gas particulate sampler is 5 L/min ~ 80 L/min, and its performance and technical indicators should meet HJ/T 48.

6.2 Inductively Coupled Plasma Atomic Emission Spectrometer

The main test items and measurement performance of the instrument shall conform to at least the requirements of Class B in JJG 768.

6.3 Digestion device

6.3.1 microwave digestion device. a programmable power setting function.

6.3.2 hot plate. temperature control accuracy is better than ± 5 °C.

6.3.3 Microwave digestion containers. PFA Teflon or similar materials.

6.3.4 high pressure digestion tank (inner tank. Teflon material; outer tank. stainless steel).

6.4 Laboratory equipment and equipment commonly used

6.4.1 Teflon beaker. 100 ml.

6.4.2 Polyethylene or polypropylene bottles. 100 ml.

6.4.3 ceramic scissors.

7.1 Acquisition and storage

7.1.1 Sample collection

Set the ambient air sampling point according to the requirements of HJ 664. When collecting filter samples, use a flow sampler at least Collect 10 m3 (standard state). When the metal concentration is low or PM10 (PM2.5) samples are collected, the sample can be increased as appropriate Product, sampling should be recorded in detail sampling conditions. Unorganized emissions of atmospheric particulate samples were collected according to HJ/T 55 the requirements related to the installation of monitoring points, other with the ambient air sample collection requirements. Sampling process of pollutant source gas samples according to GB/T 16157 in the implementation of particulate matter requirements. Use a soot sampler to collect filter cartridges at least 0.600 m3 (standard state dry Flue gas). When the concentration of heavy metals can be appropriate to increase the sampling volume. Such as the flue gas temperature in the pipeline is higher than the relevant gold to be collected is the melting point of the element, should take the cooling measures, so that the flue gas into the filter before the temperature is lower than the melting point of the relevant metal elements.

7.1.2 Sample storage

Filter samples collected after the dust will be twice inward fold, into the sample box or paper bag to save; filter sample collection will be Sealed inward folding, vertical put back to the original sampling sleeve closed preservation.

Samples were stored in a dry, ventilated, dark, room temperature environment.

7.2 Sample preparation

7.2.1 Nitric acid - hydrochloric acid mixed solution digestion system

7.2.1.1 Microwave digestion

Take a suitable filter or cartridge sample (eg large flow sampler rectangular filter 1/4, or cut diameter of 47 mm of the wafer; small flow sampler round filter take the whole, the filter to take the whole), with ceramic scissors (6.4.3) cut into small pieces placed in the micro (6.3.3), add 20.0 ml of nitric acid-hydrochloric acid mixed digest (5.6), so that the filter (filter) debris Immersed in, capped, placed in the digestion tank assembly and tighten, put on the microwave turntable. Set the digestion temperature to.200 °C, the duration of digestion was 15 min. After digestion, remove the digestion tank assembly, cool, rinse with water to digest the inner wall of the container, Add about 10 ml of water, put it aside for 0.5 h for extraction. The extract was filtered into a 100 ml volumetric flask and set to 100 ml with water Scale, to be tested. When the organic content is too high, can be added in the digestion of hydrogen peroxide (5.3) to decompose organic matter.

7.2.1.2 Heater digestion

Take a suitable filter or cartridge sample (eg large flow sampler rectangular filter 1/4, or cut diameter of 47 mm of the wafer; small flow sampler round filter to take the whole, the filter to take the whole), with ceramic scissors (6.4.3) cut into small pieces placed Polytetrafluoroethylene beaker (6.4.1), 20.0 ml of nitric acid-hydrochloric acid mixed digest (5.6) was added to make the filter (filter) Debris immersed, covered with a surface dish, heated at 100 ± 5 °C reflux 2 h, cooling. Rinse the inner wall of the beaker with water About 10 ml of water, put it aside for 0.5 h for extraction. The extract was filtered into a 100 ml volumetric flask and set to 100 ml with water Scale, to be tested. When the organic content is too high, can be digested by adding the right amount of hydrogen peroxide (5.3) digestion to decomposition Organic matter.

7.2.2 Other digestion systems

In addition to the above nitric acid - hydrochloric acid mixed solution digestion system (7.2.1), according to the actual work needs to choose other to meet Accuracy and precision requirements of the digestion system and digestion method. Such as nitric acid (Appendix E.1), nitric acid - hydrofluoric acid -Hydrogen peroxide/perchloric acid) system (Appendix E.2; Appendix E.3; Appendix E.4) and the determination of Si, Al, Ti, Mn and other constant elements of the alkali melting method (Appendix E.5) and other full digestion system and high pressure sealing tank digestion method. Nitric acid-hydrofluoric acid-Hydrogen peroxide/perchloric acid, alkali melting and other full amount of digestion system suitable for atmospheric particle source analysis for the purpose of collecting pollution sources Determination of Elements in Samples and Environmental Samples.

7.2.3 Laboratory samples are blank

Take the same lot as the sample, the same area of the blank filter or filter cartridge, according to the same steps as the preparation of the sample (7.2.1 or 7.2.2) Preparation of laboratory blank samples.

8.1 Instrument parameters

Using the instrument manufacturer recommended instrument operating parameters. Table 1 gives the reference analysis conditions for measurement.

Table 1 ICP-OES measurement reference analysis conditions

Ignite the plasma, according to the manufacturers to provide the operating parameters set, until the instrument preheat to the indicators after the stability of the open Start the measurement.

8.2 Wavelength selection

In the laboratory equipment manufacturers recommended by the best measurement conditions, for each selected element selected 2 to 3 lines for the best analysis spectrum of each element was selected on the basis of the strength, spectrum and interference of each line.

line. The recommended wavelengths for each metal element are shown in Appendix B.

8.3 Analysis and determination

8.3.1 Calibration curve

Based on the actual chemical composition of the particulate matter, Table 2 gives the standard solution concentration reference range. Suggestions within this range Standard series of blank solution (5.9), followed by the addition of multi-element standard stock solution (5.13) preparation of 3 to 5 concentrations of the standard series. The concentration points were rinsed with nitric acid solution (5.9) to 50.0 ml. Can be adjusted according to the actual sample concentration of the element to be measured Whole calibration curve concentration range.

The standard solution is sequentially introduced into the emission spectrometer for measurement, with the concentration as the abscissa, the element response intensity is the ordinate Line linear regression, the establishment of calibration curve.

Table 2 Calibration Curve Standard Solution Reference Concentration Range

Element concentration range (mg/L) Co, Cr, Cu, Ni, Pb, As, Ag, Be, Bi, Cd, Sr 0.00 to 1.00 Ba, Mn, V, Ti, Zn, Sn, Sb 0.00 to 5.00 Al, Fe, Ca, Mg, Na, K 0.00 to 10.0

8.3.2 Sample determination

Before analyzing the sample, rinse the system with the system wash solution (5.10) until the blank strength value is minimized and the signal to be analyzed After stabilization, the sample is analyzed. During sample measurement, if the concentration of the element to be measured in the sample exceeds the calibration curve, Diluted after re-determination.

9.1 Results calculation

The concentration of the metal elements in the particles is calculated by the following formula.

Where. rho - concentration of metal elements in particles, µg/m3;

C - concentration of metal elements in the sample, µg/ml;

0c - the concentration of metal elements in the blank sample, µg/ml.

SV - volume or volume after digestion of sample or sample;

N - the number of copies of the filter (ie, the ratio of the area of the sample filter to the area taken during digestion, for the cartridge n = 1).

StdV - sampled volume (m3) in standard (273 K, 101.325 Pa). On the source of waste gas samples, stdV the volume of dry flue gas in the standard state (m3).

9.2 The result is shown when the measurement is greater than or equal to 1.00 µg/m3, the data retains three significant digits. When the result is less than 1.00 Mg/m3, the retention of the effective digits after the decimal point is consistent with the detection limit of the method to be measured.

11.1 Blank sample

Two blank samples should be analyzed for each batch. Blank samples include reagent blank and filter (or cartridge) blank. test the measured value of the target element in the blank should be less than the lower limit of the determination. Including the digestion of the whole process of the filter or filter cartridge blank sample target element the measured value of the element shall be less than or equal to 1/10 of the emission standard limit. If you can not meet the requirements, consider the appropriate increase in the amount of sampling, so that the measured value of the target element in the particulate matter is significantly higher than the filter or filter blank.

11.2 Calibration curve

The calibration curve is required before each batch of samples, and the correlation coefficient should be greater than 0.999. Standard with other sources the relative error should be controlled within 10% when the standard solution is close to the calibration curve.

Each measured 10 ~ 20 samples should be measured a calibration curve intermediate point concentration standard solution, the measured value and the relative value of the relative error should be <= 10%. Otherwise, the standard curve should be reestablished.

11.3 Precision

In the case of conditions permitting (eg TSP samples collected by a large flow sampler), 10% of the sample shall be taken for each batch Parallel sample measurement. If the number of samples is less than 10, at least one parallel sample should be measured. When the assay results are under test Limit to 10 times the detection limit (including 10 times the detection limit), the parallel deviation of the results of the relative deviation of <= 20%;