HJ 801-2016Ambient air and waste gas-Determination of amide compounds-Liquid chromatography (English PDF)

5.6 Amide Compounds Standard stock solution

Accurate weighing 0.100 g (accurate to ± 0.0001 g) Formamide (5.2), 0.050 g (accurate to ± 0.0001 g) N, N-Dimethylformamide (5.3), 0.100 g (accurate to ± 0.0001 g) N, N-dimethylacetamide (5.4) and 0.050 g (exact to ± 0.0001 g) acrylamide (5.5), dissolved in water after the full volume into the 100 ml volumetric flask, diluted with water volume to the mark, Shake well Preparation of Formamide, N, N-Dimethylformamide, N, N-Dimethylacetamide and Acrylamide Concentration of 1000 Mg/L, 500 mg/L, 1000 mg/L and 500 mg/L amide compounds were mixed at 4 ° C, Dark and sealed can be stored for three months, should be used to restore to room temperature and shake. You can also purchase commercially available certified reference materials Conditions Refer to the product description.

5.7 Amide Compounds Standard Use Liquid

Accurate removal of 5.00 ml of amide compound standard stock solution (5.6) in a 100 ml volumetric flask, diluted with water to Marking, shaking. N, N-dimethylformamide, N, N-dimethylacetamide and acrylamide were prepared in the form of formamide, N, N-dimethylformamide 50.0 mg/L, 25.0 mg/L, 50.0 mg/L and 25.0 mg/L amide compounds. Turn into brown glass Glass reagent bottles, frozen below 4 °C, dark and sealed can be stored for 6 d. Use should be restored to room temperature, and shake.

7.1 Collection of samples

Before sampling, the sampler should be airtight and flow calibrated and open the pump at 1.0 L/min.

Minute, replace the air of the sampling system.

7.1.1 Ambient air samples

The sampling of ambient air shall comply with the relevant provisions in HJ/T 194. At the time of sampling, a porous glass of 10.0 ml of experimental water will be used (6.5), connected with a polytetrafluoroethylene hose or a silicone rubber tube (6.10) with a Teflon film, (6.3), the ambient air sample was collected at a flow rate of 0.5 L/min for 60 min, and the temperature and atmospheric pressure of the sampling point were recorded number.

7.1.2 Fixed sources of waste gas samples

The sampling of the waste gas of the fixed pollution source shall comply with the relevant provisions in GB/T 16157. At the time of sampling, 50.0 ml of the experiment will be performed (6.6), a polytetrafluoroethylene hose or a silicone rubber tube (6.10) coated with a polytetrafluoroethylene film, Connect to the flue gas sampler (6.4), heat the sampling gun to above 120 ° C, and collect the fixed source of waste at 1.0 L/min Gas sample 30 min. According to the actual concentration, appropriate to extend or shorten the sampling time, record the sampling temperature and pressure and other parameters.

Note 1. When the temperature of the sampling gas is high, the perforated glass plate (6.6) can be cooled with an ice water bath.

7.1.3 Full program blank samples

Each sampling should be accompanied by at least one full program blank sample. Will be the same batch of 10.0 ml of experimental water filled with porous glass plate suction (6.6) or the same batch of 50.0 ml of experimental water with a porous glass plate to absorb the bottle (6.6) to the sampling site, open it both ends are not connected to the sampler and closed after 1 minute. Follow the same conditions as the sample transport and storage (7.2) room.

7.2 Transport and storage of samples

After the sample was collected, the porous glass plate was closed with a Teflon hose or a silicone rubber tube (6.10) filled with polytetrafluoroethylene film Absorbent tube (6.5) or perforated glass plate (6.6) inlet and outlet ports, placed vertically in the freezer (6.9) save. If not measured in time, the sample should be refrigerated below 4 °C, dark and sealed to save, 5 d to complete the analysis and determination.

7.3 Preparation of samples

7.3.1 Ambient air samples

The ambient air sample absorption solution (7.1.1 collected by the absorption solution) into the total volume of 10 ml colorimetric tube, the volume of water to 10 ml Marking, shaking. Filter with a 0.22 µm aqueous syringe filter (6.8) and discard 2 ml of the initial stock and collect the filtrate to 2 ml of brown Bottle, to be tested.

7.3.2 Fixed sources of waste gas samples

The fixed source of waste gas sample absorption solution (7.1.2 collected by the absorption solution) into the 50 ml colorimetric tube, with water Capacity to 50 ml mark, shake. Filter with a 0.22 µm aqueous syringe filter (6.8), discard 2 ml of the initial solution and collect the filtrate to 2 ml Brown vials, to be tested.

7.3.3 Full program blank samples

The whole program blank sample (7.1.3) is prepared in accordance with the preparation of the sample of the ambient air sample (7.3.1) or the fixed source of waste gas Preparation of sample (7.3.2) The same procedure was used to prepare a full program blank sample.

7.3.4 Laboratory blank samples

Instead of the sample with the same volume and the same volume of experimental water, follow the preparation of the sample with the ambient air sample (7.3.1) or Preparation of fixed source sample (7.3.2) The same procedure was used to prepare a laboratory blank sample.

8.1 Liquid Chromatographic Reference Conditions

Column temperature. 30 ° C;

Mobile phase. water. acetonitrile = 97. 3 (v/v);

Detection wavelength. 198 nm;

Auxiliary wavelength. 195nm, 205nm;

Injection volume. 5.0 µl;

Flow rate. 0.5 ml/min.

8.2 Standard curve drawing

Respectively, 0.50 ml, 5.00 ml, 10.00 ml, 20.00 ml, 50.00 ml of amide compounds standard use of liquid (5.7) Placed in a group of 50 ml volumetric flask, the water volume to the mark, shake, the standard series of the target compound concentration in Table 1. by Low concentration to high concentration followed by removal of 5.0 µl into the liquid chromatograph, according to the liquid chromatography reference conditions (8.1) for analysis set. The concentration of the target compound in the standard series solution (mg/L) was the abscissa, with the peak height or peak area as the ordinate, Standard curve of amide compounds. The standard chromatograms of amide compounds are shown in the liquid chromatographic conditions specified in this standard figure 1.

Table 1 Amide Compounds Standard Series Concentration

1-carboxamide; 2-acrylamide; 3-N, N-dimethylformamide; 4-N, N-dimethylacetamide

Figure 1 Standard chromatogram of amide compounds

8.3 Determination of samples

Take a 5.0 µl sample (7.3) into a liquid chromatograph according to the same chromatographic conditions (8.1) and steps as the standard curve (8.2), and the retention time and peak height (or peak area) of the chromatographic peak were recorded. Standard color of amide compounds the retention time of the spectra was determined by the external standard method, and the amide compound concentration in the samples was quantitatively calculated.

9.1 Results calculation

Standard Series Concentration (mg/L) Serial number Formamide N, N-dimethylformamide N, N-dimethylacetamide acrylamide 1 0.50 0.25 0.50 0.25 2 5.00 2.50 5.00 2.50 3 10.0 5.00 10.0 5.00 4 20.0 10.0 20.0 10.0 5 50.0 25.0 50.0 25.0 the concentration of amide compounds in ambient air and exhaust gas (mg/m3) is calculated according to equation (1) SV CVC 11 × = (1) where. C-ambient air or exhaust gas amide compounds concentration, mg/m3;

C1 - the concentration of the resulting amide compound calculated from the standard curve, mg/L;

V1 - Absorbent liquid volume, ml;

Vs - the sampling volume under the standard state (101.325 kPa, 273.2 K), L.

9.2 The result is shown for ambient air, when the result is less than 1 mg/m3, the remainder is left after the decimal point; when the result is greater than or equal at 1 mg/m3, three valid digits are retained.

For fixed sources of waste gas, when the determination results less than 10 mg/m3, retained to the decimal point after a; when the determination of the results when you are greater than or equal to 10 mg/m3, keep three significant digits.

10.1 Precision

Six laboratories were treated with formamide (0.50 mg/L, 2.0 mg/L and 10 mg/L), N, N-dimethylformamide (0.50 Mg/L, 2.0 mg/L and 10 mg/L), N, N-dimethylacetamide (0.50 mg/L, 2.0 mg/L and 10 mg/L), acryloyl Amine (0.25 mg/L, 1.0 mg/L and 5.0 mg/L) of the amide compound mixed standard solution with a uniform blank spiked sample Six times of repeated determination.

The relative standard deviations (RSDs) of formamides were 3.4% ~ 10%, 2.1% ~ 6.7%, 0.7% ~ 4.9% the relative standard deviations were 3.1%, 2.4% and 3.0%, respectively, and the repeatability limits were 0.04 mg/m3, 0.09 mg/m3, 0.28 mg/m3, the reproducibility limits were 0.04 mg/m3, 0.10 mg/m3, and 0.39 mg/m3, respectively.

The relative standard deviations (RSDs) of N, N-dimethylformamide were 3.5% ~ 6.5%, 3.3% ~ 5.7%, 3.2% ~ 5.6% the relative standard deviations were 4.7%, 4.2%, 3.1%, and the reproducibility limits were 0.03 mg/m3, 0.09 mg/m3, 0.39 mg/m3, and the reproducibility limits were 0.04 mg/m3, 0.11 mg/m3 and 0.46 mg/m3, respectively.

The relative standard deviations (RSDs) of N, N-dimethylacetamide were 4.0% ~ 8.1%, 3.5% ~ 6.3%, 3.4% ~ 6.1% the relative standard deviations were 4.6%, 4.6% and 2.8%, respectively. The repeatability limits were 0.03 mg/m3, 0.10 mg/m3, 0.43 mg/m3, reproducibility limit was 0.04 mg/m3, 0.13 mg/m3, 0.47 mg/m3, respectively.

The relative standard deviations of acrylamide laboratories were 3.6% ~ 10%, 3.3% ~ 7.0%, 2.7% ~ 4.4%, respectively.

The relative standard deviations were 4.3%, 4.1% and 2.5%, respectively, and the repeatability limits were 0.02 mg/m3, 0.05 mg/m3, 0.16 Mg/m3, reproducibility limit of 0.02 mg/m3, 0.06 mg/m3, 0.19 mg/m3, respectively.

10.2 Accuracy

The six laboratories were treated with formamide (labeled titers of 5.0 µg, 50 µg and 250 µg), N, N-dimethylformamide 50 µg and.200 µg), N, N-dimethylacetamide (plus titer of 5.0 µg, 50 µg and.200 µg) and C (Labeled with a scalar of 2.5 µg, 25 µg and 100 µg) were subjected to 6 replicates.

The recoveries of formamides were 101% ~ 111%, 97.6% ~ 105%, 98.1% ~ 102%, respectively.

Values were 107% ± 6.4%, 102% ± 5.2%, 100% ± 3.2%.

The recoveries of N, N-dimethylformamide were 94.7% ~ 109%, 95.7% ~ 102%, 97.7% ~ 102% the final recoveries were 103% ± 9.6%, 97.6% ± 4.6% and 100% ± 4.4%, respectively.

The recoveries of N, N-dimethylacetamide were 94.6% ~ 108%, 94.7% ~ 102%, 97.0% ~ 103% the final recoveries were 104% ± 9.6%, 97.7% ± 6.0% and 99.0% ± 6.0%, respectively.

The recoveries of acrylamide were 94.4% ~ 107%, 97.3% ~ 103%, 98.5% ~ 103%, respectively.

The final values were 103% ± 9.0%, 101% ± 4.6%, 101% ± 5.0%, respectively.

Details of precision and accuracy are given in Appendix A.

11.2 Blank analysis

Each analysis is done at least one lab blank and one full program blank to check for possible interference, target combinations the measured value of the object shall not be higher than the detection limit of the method.

11.3 Calibration

11.3.1 Initial calibration

The initial use of the instrument, or in the instrument repair, replacement column or continuous calibration failed, the need to re-draw the standard curve, Perform initial calibration.

11.3.2 Continuous calibration

For each 20 samples or each batch (less than 20 samples/batch), a continuous calibration of the standard curve quasi. The relative error of continuous calibration should be <= 20%, otherwise you should find the cause, or re-draw the standard curve. According to formula (2) Calculate the relative error (D) between cC and calibration point iC.

CCD (2)

Where.

D - cC relative error with calibration point iC,%;

IC - mass concentration of calibration points;

CC - Determines the mass concentration of the calibration point.