HJ 540-2016Stationary source emission - Determination of arsenic- Silver diethyldithiocarbamate spectrophotometric method (English PDF)

5.15 Potassium iodide solution. rho (KI) = 150 g/L

Weigh 15 g of potassium iodide (5.2), dissolved in water and diluted to 100 ml beaker.

5.16 Stannous chloride solution. rho (SnCl2 · 2H2O) = 400 g/L.

Weigh 48 g of stannous chloride (5.3), add 50 ml of hydrochloric acid (5.10), dissolve it by heating, and then diluted with water to 100 ml Beaker, ready for use.

5.17 lead acetate solution. rho [Pb (CH3COO) 2] = 100 g/L.

Weigh 10 g of lead acetate (5.4), dissolve in water and dilute to 100 ml beaker.

5.18 Silver diethyldithiocarbamate Absorbate. omega (C5H10AgNS2) = 0.25%.

Weigh 1.25 g of silver diethyldithiocarbamate (5.5), add 100 ml of trichloromethane (5.11) and 4 ml of tri Alcohol (5.12) was stirred and diluted to 500 ml with trichloromethane (5.11), shaken, left overnight, filtered with absorbent cotton in the brown reagent bottle, in the 4 °C below the cold, dark can be stored for 3 months.

5.19 Sodium hydroxide solution. omega (NaOH) = 40%.

Weigh 40 g of sodium hydroxide (5.7), dissolve with water and dilute to 100 ml beaker.

5.20 arsenic standard stock solution. rho (As) = 1.00 mg/ml.

Accurately weigh 0.0660 g (accurate to 0.0001 g) arsenic trioxide (5.6), add 10 ml of sodium hydroxide solution (5.19), Dissolved in heat. The whole volume into the 100 ml volumetric flask, dilute the volume to the mark with water. Store in a brown reagent bottle at 4 ° C or lower Refrigerated, sealed for 3 months. You can also purchase commercially available certified materials.

5.21 arsenic standard use of liquid. rho (As) = 1.00 µg/ml.

Arsenic standard stock solution (5.20) placed in room temperature, diluted with water preparation, temporary with the allocation.

5.22 Lead acetate

10 g of absorbent cotton immersed in 100 ml of lead acetate solution (5.17), 30 min after the removal, at room temperature to dry, dark Preserved in the grinding glass bottles, the preservation period of 1 year.

5.23 Quartz fiber filter cartridge

Should be pre-baked in the muffle furnace at 300 °C for 3 h, placed in a dryer to cool to room temperature. The arsenic in the digestion of the blank filter cartridge the amount of not more than 1.3 µg. The particle size of particles with particle size greater than 0.3 µm is not less than 99.9%.

7.1 Collection of samples

In accordance with the relevant provisions of GB/T 16157 implementation. Place the sampler with the quartz fiber filter cartridge into the sampling point in the exhaust cylinder Constant speed sampling. Select the appropriate sampling time according to the concentration of arsenic, sample for 1 hour, or at 1 hour intervals Collected three to four samples, while measuring temperature, pressure and other parameters. After sampling, carefully remove the cartridge, the seal inward Folded, put back into the original filter box. Samples of particulate matter were collected using a soot sampler with a total sample volume of not less than 0.4 m3 (Standard state).

When the flue gas temperature is higher than 100 °C, should take the cooling measures, so that the flue gas into the filter before the temperature is below 100 °C, the specific side the reference can be made to HJ 77.2.

7.2 Preservation of samples

The collected samples should be stored in a desiccator and completed within 7 days.

7.3 Preparation of samples

Use a polytetrafluoroethylene scissors (6.4) to cut the filter sample into flakes (do not shake off the dust), place it in a.200 ml Erlenmeyer flask, Add 20 ml water infiltration. Adding 20 ml of nitric acid (5.8), 4 ml of sulfuric acid (5.9) and 2 drops to 3 drops of hydrogen peroxide (5.13) Bottle into the glass funnel, heated in the hot plate (6.3) to the state of micro-boiling to maintain 2 h ~ 3 h, remove the funnel, with the appropriate amount of experiment Rinse the funnel with water to the conical flask and continue heating in the slightly boiling state until the solution is near dry and allowed to cool. Add to the conical flask 25 ml of water (to be immersed in the sample), placed in the ultrasonic scrubber (6.6) for 5 min, remove the conical flask, with medium-speed quantitative filter Paper filter; this step (plus 25 ml of water, ultrasound and filtration) repeated 5 times to 6 times. Combine the filtrate in a beaker and place it in electricity Hot plate (6.3) to drain nitric acid until the solution remains about 4 ml. After cooling, add a small amount of experimental water to wash the beaker Wall, the whole solution will be transferred to the arsenide bottle (6.5), add water to 50 ml, shake.

Note 2. nitric acid, sulfuric acid, hydrogen peroxide digestion of the sample, the organic matter must be completely decomposed, otherwise the results are low. The content of organic matter in the sample is higher than that in the sample for a long time, should be added again hydrogen peroxide heating digestion to precipitate into gray, and the liquid level is calm, no longer produce nitrogen oxide brown smoke so far. Together and then the filtrate must be evaporated to produce white smoke to drive nitric acid, otherwise the addition of zinc particles will produce brown gas, resulting in measurement failure, in case of Resampling analysis.

7.4 Preparation of blank sample

7.4.1 Preparation of laboratory blanks

Take the same batch of filter cartridges and prepare a laboratory blank sample according to the same procedure as for sample preparation (7.3).

7.4.2 Preparation of full program blank samples

Each sampling at least take the same batch of blank filter cartridge two, to the sampling site as a whole program blank sample. Follow the sample with Preparation of the procedure (7.3) The same procedure to prepare a full program blank sample.

8.1 Calibration curve

8.1.1 Take 7 hydrogen arsenic vials, add 0.00 ml, 1.00 ml, 3.00 ml, 5.00 ml, 10.00 ml, 15.00 ml

And 25.00 ml of arsenic standard using liquid (5.21), add 7 ml of sulfuric acid solution (5.14), add water to 50 ml, then add 5 ml Potassium iodide solution (5.15) and 3 ml stannous chloride solution (5.16), shake and let stand for 15 min. This standard series of arsenic content points Do not be 0.00 µg, 1.00 µg, 3.00 µg, 5.00 µg, 10.0 µg, 15.0 µg, 25.0 µg.

8.1.2 Add 3 g to 4 g of arsenic-free zinc pellets (5.1) to solution (8.1.1) and immediately with argon with lead acetate (5.22) the tube was connected to an absorption tube containing 5.0 ml of silver diethyldithiocarbamate absorption solution (5.18). After 1 h of reaction, the absorption was removed Tube, along the airway wall by adding trichloromethane (5.11) and fixed to the absorption tube 5.0 ml scale, to be measured.

Note 3. High temperature in summer, too fast response, incomplete absorption, the results are low. If the room temperature is higher than 30 °C, the bottle can be placed in the ice bath cool down.

8.1.3 at the wavelength of 510 nm, with 10 mm cuvette to chloroform (5.11) as a reference, measured absorbance to arsenic Content (µg) for the abscissa, absorbance value for the vertical axis, draw the calibration curve.

8.2 Determination of sample

Add 5 ml of potassium iodide solution (5.15) and 3 ml of stannous chloride solution (5.16) to the sample (7.3) and shake well. Stand still After 15 min, the absorbance of the sample was measured according to the same procedure (8.1.2 to 8.1.3) as the plot of the calibration curve.

8.3 Determination of blank sample

The laboratory blank sample (7.4.1) and the whole program blank sample (7.4.2) were measured in the same manner as in the determination of the sample (8.2) of the absorbance.

9.1 Results calculation

Calculate the concentration of arsenic in the particulate matter of the fixed source of pollution according to the formula (1), mg/m3.

AA a

B V 1000

Where the concentration of arsenic in the particulate matter of the fixed source (in As), mg/m3;

A - the absorbance of the sample;

0A - absorbance of laboratory blank samples;

A - the intercept of the calibration curve;

B - the slope of the calibration curve;

NdV - the sampling volume of the dry flue gas under the standard state (273 K, 101.325 kPa), m 3.

9.2 The result is shown when the measured value is less than 0.1 mg/m3, the result is three after the decimal point; when the measured value is greater than or equal to 0.1 mg/m3, the result retains three significant digits.

10.1 Precision

(5.00 µg/50 ml, 10.00 µg/50 ml and 15.00 µg/50 ml) in the three laboratories A standard blank filter cartridge was loaded with 6 samples in parallel. The relative standard deviations in the laboratory were 2.8% ~ 4.6% 1.1% ~ 6.8% and 1.1% ~ 7.5% respectively. The relative standard deviations were 7.6%, 2.7% and 1.2%, respectively. The repeatability limits were 0.49 µg/50 ml, 1.3 µg/50 ml and 1.6 µg/50 ml, respectively. The reproducibility limits were 1.1 µg/50 ml, 1.4 µg/50 ml and 1.5 µg/50 Ml.

10.2 Accuracy

(5.00 µg/50 ml, 10.00 µg/50 ml and 15.00 µg/50 ml) in the three laboratories A standard blank filter cartridge was loaded with 6 samples in parallel. The relative errors in the laboratory were -19.0% -0.4%-5.1% ~ -1.0% and -2.9% ~ 0.3%; the relative error of the final value were -4.6% ± 14.5%, -1.4% ± 5.4%-0.9% ± 2.4%.