HJ 685-2014Stationary source emission. Determination of lead. Flame atomic absorption spectrophotometric method (English PDF)

5.5 Lead standard stock solution. rho (Pb) = 1000 mg/L

Accurately weigh 1.0000 g spectroscopically pure metallic lead placed in 100ml beaker, add nitric acid in a fume hood (5.1) 15 ml, Slowly heated on a hot plate until completely dissolved, nitric acid solution (5.3) and dilute to 1000ml. Into polyethylene plastic Bottle, stored in the refrigerator, at least stable for one month. It can also be purchased commercially available certified reference materials/substances.

5.6 Lead standard solution. rho (Pb) = 100 mg/L

Imbibe lead standard stock solution (5.5) 10.00 ml to 100 ml volumetric flask, dilute to the mark with a solution of nitric acid (5.3), Mix well.

5.7 Acetylene, purity of not less than 99.6%

6.1 Flame atomic absorption spectrophotometer

6.2 Lead hollow cathode lamp.

6.3 dust sampler, sampling flow rate (5 ~ 80) L/min, performance and other technical indicators in line with the provisions of HJ/T 48's.

6.4 Quartz fiber cartridge

Lead content of not more than 5µg. Barrier efficiency particle size greater than 3 µm is not less than 99.9%.

6.5 thermostat electric hot plate, (40 ~ 200) °C.

6.6 filtration device, 0.45 µm cellulose acetate material or similar properties of the membrane.

6.7 Teflon scissors.

6.8 General Commonly used laboratory instruments and equipment.

7.2 Field blank

With each sample batch taking at least two cartridges, sampling site to site as a blank sample.

Save 7.3 sample

Sampling is completed, carefully remove the cartridge seal inwardly folded back into the original cartridge box vertically, back to the lab for analysis.

7.4 Preparation of the sample

PTFE scissors Shredded cartridge, into 250 ml Erlenmeyer flask, moistened with a little water, add 50 ml Nitric acid solution (5.4), 15 ml of hydrogen peroxide (5.2), inserted into the small funnel, a hot plate heated to a boil, held 2 h, to be cooled and then carefully added dropwise 5 ml of hydrogen peroxide (5.2), can be supplemented with a small amount of water, if necessary, continue to boil for half an hour, cooling After filtration. The filtrate was transferred to a beaker, the above solution of nitric acid (5.3) washing the flask, residues and suction flask three times. wash After the wash liquid and the filtrate were combined, evaporated on a hot plate to boil nearly dry. Then add 2 ml of nitric acid solution (5.4), heating residue Residue is dissolved, all transferred to a 50 ml volumetric flask with water to volume (V), shake test.

7.5 Preparation of the laboratory sample blank

Take the same batch number two blank cartridge, 7.4 reference laboratory method for preparing a blank sample.

Analysis Step 8

8.1 Reference measurement instrument conditions

Reference instrument conditions were as follows.

Wavelength. 283.3 nm; slit width. 0.5 nm; the flame type. air - acetylene; burner height. 8 mm.

8.2 Calibration

Take seven 100 ml flask, were added to the lead standard solution (5.6) 0.00,0.50,1.00,2.00,4.00, 8.00 and 10.00 ml, then diluted to the mark with a solution of nitric acid (5.3), this series of standard concentration of 0.00,0.50, 1.00,2.00,4.00,8.00 and 10.00 mg/L. Procedure Set up the instrument according to the manufacturer's instructions and select the instrument parameters, Absorbance measurement standard series to draw absorbance of lead concentration (mg/L) calibration curve.

8.3 Determination

Press the calibration curve drawn when the instrument conditions and measured the concentration of the sample (7.4) of (rho) calculated. When the sample response when in the upper range other than the calibration curve should be used nitric acid solution (5.3) was diluted to an appropriate multiplier (F.), So that the response value Falls within the linear range of the calibration curve.

8.4 Blank test

Press the calibration curve drawn when the working conditions of the instrument measured and calculated concentration laboratory blank sample (7.5) of (rho 0 (avg)).

9.1 Calculation Results

Calculate stationary source exhaust particles of lead content.

ndV

) rho (0

rhorho fPb

Where. rho (Pb) - stationary source exhaust particles of lead concentration, mg/m3 rho- sample lead concentration, mg/L;

rho 0 (avg)- laboratory blank sample lead concentration, mg/L;

Volume V- sample volume, ml;

Dilution f- sample;

Vnd- standard conditions (273 K, 101.325 kPa) dry flue gas sample volume, m3.

9.2 The results are shown when the measured value is less than 0.1 mg/m3, the results of two decimal places when measured value is greater than 0.1 mg/m3, results Three significant digits expressed in units of mg/m3.

10.1 Precision

6 laboratories lead concentration of 115 µg/m3,230µg/m3,574 µg/m3 simulated exhaust gas sample (sample volume to 0.5 m3 meter) were measured precision.

Laboratory relative standard deviation of 1.2% ~ 5.7%, from 0.8% to 7.3% and 1.6% ~ 8.5%;

Interlaboratory relative standard deviations were 14.0%, 12.7% and 20.9%;

Repeatability limits were. 12.1 µg/m3,25.5 µg/m3 and 53.1 µg/m3;

Reproducibility limits were. 42.5 µg/m3,76.0 µg/m3 and 134.5 µg/m3.

10.2 Accuracy

Six laboratories using standard samples of fly ash (w (Pb) = 1149mg/kg) group of preparation provided, weighed 0.050g, 0.100g and 0.250g, respectively, added to a blank cartridge, the as lead concentrations were 115µg/m3,223µg/m3,574µg/m3 three Concentration simulated exhaust gas sample (sample volume to 0.5m3 meter) accuracy of the experiment were.

Relative error were. -31.6% to 3.4% - to 0.9% and 28.1% -21.0% -3.7%;

The relative error of the final values were. (- 9.2 ± 12.8) 0.050%, (- 11.6 ± 11.2) 0.100%, and (-11.4 ± 10.5) 0.250%.