HJ 539-2015Ambient air. Determination of lead. Graphite furnace atomic absorption spectrometry (English PDF)

7.1 Collection of samples

The sampling of the particles is carried out in accordance with the sampling requirements for particulate matter in GB/T 15432 and HJ/T 194. Sampling should be noted in detail Recorded environmental conditions.

7.2 Preservation of samples

After collecting the sample filter and the whole program blank filter folded into a clean paper bag or capsule, into the dryer to save.

7.3 Preparation of samples

7.3.1 Heater digestion

The filters were cut into small pieces, placed in a conical flask, and then 10 ml of nitric acid (5.1), 5 ml of hydrochloric acid (5.2) and 3 ml of hydrogen peroxide (5.3), standing for 20 min ~ 30 min or so, until the initial reaction tends to calm, on the hot plate Heated to micro-boiling for digestion. Steamed to dry, then add 5 ml of nitric acid (5.1), 1.5 ml of hydrogen peroxide (5.3), Heat to dry and cool. Then add 5 ml of nitric acid (5.4) to dissolve slightly, the solution is filtered into a 50 ml volumetric flask, and rinse the filter residue with the concentration of 1% nitric acid (5.5) at least three times, the washing liquid and the filtrate combined, Scale and shake.

7.3.2 Microwave digestion

The filter was cut into small pieces, placed in a digestion tank, and then 8 ml of nitric acid (5.1), 2 ml of hydrochloric acid (5.2) and 1 ml of hydrogen peroxide (5.3), standing for 2 h ~ 3 h or so, until the initial reaction tends to calm, the digestion. To be eliminated After completion of the solution, transfer to the beaker and add 5 ml of nitric acid solution (5.4) to dissolve slightly. The solution is filtered to a 50 ml volumetric flask and mixed with nitric acid solution (5.4).

Microwave digestion instrument parameters can refer to the instructions to choose, refer to the conditions in Table 1.

Table 1 Microwave digestion conditions

Digestion time t (min) digestion power E (W) digestion temperature T1 (°C) tank temperature T2 (°C) 15 1000 120 100 5 1250 185 120 30 1250 185 120

7.4 Preparation of blank sample

7.4.1 Full program blank

Will be the same batch of two filters to the sampling site, do not collect samples. After sampling, bring back to the laboratory, according to the sample system Prepared (7.3) to prepare a full program blank sample.

7.4.2 Lab blank

The two batches of the same batch were prepared as laboratory blank samples according to the preparation of the sample (7.3).

8.1 Graphite Furnace Atomic Absorption Spectrophotometer Operating Conditions

Instrument measurement parameters can refer to the instructions to choose, refer to the working conditions in Table 2.

Table 2 Graphite Furnace Atomic Absorption Spectrophotometric Working Conditions

The wavelength is 283.3 nm Lamp current 8 mA Slit 0.5 nm Drying temperature and time 90 °C, 15 s; 120 °C, 15 s. Two dry Ashing temperature and time of 700 °C, 20 s Atomization temperature and time 1400 °C, 5 s Cleaning temperature and time 2500 °C, 5 s the argon gas flow rate was 0.2 L/min Whether the atomic phase is stopped Injection volume 20 µl Substrate modifier 2 µl Background deduction method Zeeman

8.2 Calibration curve

8.2.1 Preparation of standard series

Take 6 50 ml volumetric flasks and prepare lead standard series according to Table 3. Diluted with nitric acid solution (5.5) to the mark, shake.

Table 3 Lead Standard Series

Bottle number 0 1 2 3 4 5 Lead standard use liquid (ml) 0.00 1.00 2.00 3.00 4.00 5.00 Lead concentration (µg/L) 0.00 10.0 20.0 30.0 40.0 50.0

8.2.2 Calibration curve

From low concentration to high concentration, followed by the lead into the graphite tube lead standard solution, adding 2 µl ammonium dihydrogen phosphate matrix modifier (5.9), according to the selected instrument operating conditions, the determination of lead standard series of absorbance, and the establishment of calibration curve of the linear back Return equation.

8.3 Determination of samples

The absorbance of the sample (7.3) was measured by the instrument operating conditions and operating procedures when the calibration curve was drawn.

8.4 Determination of blank

The absorbance of the blank sample (7.4) was measured by the instrument operating conditions and operating procedures when the calibration curve was drawn.

9.1 Results calculation

Based on the measured absorbance values, the concentration of lead in the sample and the blank sample was calculated from the linear regression equation, Calculate the concentration of lead in ambient air (µg/m3).

rho (Pb) =

Xxx

50) (1 0rhorho

Where. rho (Pb) - ambient air lead concentration (µg/m3);

1rho - Lead concentration in sample, µg/L.

0rho - average of lead concentration in laboratory blank samples, µg/L;

50 - sample solution volume, ml;

TS - total area of sample filter, cm2;

AS - the sample area of the sample taken after the measurement, cm2.

NV - standard volume (101.325 kPa, 273 K) under the sampling volume, m3;

9.2 The result is shown when the measured value is less than 1 µg/m3, the result retains two decimal places. When the measured value is greater than or equal to 1 µg/m3, the result Expressed in three significant digits, in µg/m3.

10.1 Precision

6 laboratories with standard value of 403 ± 32 mg/kg lead standard samples for precision experiments, were weighed quality 0.025 g, 0.04 g, 0.05 g three groups of samples were tested in six parallel tests. the relative standard deviation of the laboratory were. 1.84% ~ 4.07%, 1.49% ~ 4.52%, 1.61% ~ 6.52% respectively. The relative standard deviations were 4.86%, 4.68% and 5.41% respectively.

The reproducibility limit r was. 38.1 mg/kg, 29.4 mg/kg, 38.4 mg/kg; the reproducibility limit R was 66.2 mg/kg, 58.3 mg/kg, 68.9 mg/kg.

10.2 Accuracy

6 laboratory with standard value of 403 ± 32 mg/kg lead standard sample for the accuracy of the experiment, were weighed 0.025 g, 0.04 g, 0.05 g three groups of samples were tested in six parallel tests. the relative error in the laboratory were -2.48% 11.2%, - 7.69% ~ 4.96%, 8.68% ~ 4.71% respectively. The relative error values were 2.78% ± 0.100%, - 2.11% ± 0.092%, - 2.69% ± 0.104%.

11.1 Blank

Each batch of samples should be at least two laboratory blanks and two full program blanks, the determination of the results should be lower than the lower limit of determination.

11.2 Calibration curve

Each batch of samples need to be calibrated curve, with a linear fitting curve calibration, the correlation coefficient should be greater than or equal to 0.995.

11.3 Quantitative calibration control

During the assay, each of the 10 samples should be re-measured the standard solution at the midpoint of the calibration curve concentration. Determination of knot the relative deviation of the point concentration on the calibration curve should not exceed ± 10%. Otherwise it should find out the cause and correct, to be stable instrument the first 10 samples were re-measured.

11.4 Parallel sample control

Each batch of samples should be 10% of the proportion of parallel sample determination, the number of samples less than 10, should be measured at least one level Row of the measured results of the relative deviation of not more than 20%.

11.5 Blank spike and matrix spike control

Each batch of samples should be at least 10% of the blank spike or matrix spike recovery test, the number of samples less than 10 at least one the recovery rate should be in the range of 80% ~ 120%.