HJ 779-2015 English PDF

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HJ 779-2015: Ambient air. Determination of hexavalent chromium(Ⅵ). Ion chromatography with post-column method
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HJ 779-2015	229	Add to Cart	3 days	Ambient air. Determination of hexavalent chromium(Ⅵ). Ion chromatography with post-column method	Valid

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Basic data

Standard ID: HJ 779-2015 (HJ779-2015)
Description (Translated English): Ambient air. Determination of hexavalent chromium(��). Ion chromatography with post-column method
Sector / Industry: Environmental Protection Industry Standard
Word Count Estimation: 10,172
Date of Issue: 2015-12-04
Date of Implementation: 2016-01-01
Quoted Standard: HJ/T 194; HJ 93; HJ 618
Regulation (derived from): Ministry of Environment Announcement 2015 No.81
Issuing agency(ies): Ministry of Ecology and Environment
Summary: This Standard specifies the determination of particulate matter in ambient air hexavalent chromium ion chromatography. This Standard applies to the determination of particulate matter in ambient air hexavalent chromium.

HJ 779-2015: Ambient air. Determination of hexavalent chromium(Ⅵ). Ion chromatography with post-column method

---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Ambient air.Determination of hexavalent chromium (Ⅵ) .In chromatography with post-column method National Environmental Protection Standard of the People 's Republic of China Determination of hexavalent chromium in ambient air Post - column derivatization ion chromatography Ambient air-Determination of hexavalent chromium (Ⅵ) -Ion chromatography with post-column method 2015-12-04 released 2016-01-01 Implementation Issued by the Ministry of Environmental Protection Directory Preface .ii

1 Scope of application

2 normative reference documents

3 Principle of the method

Interference and elimination 5 reagents and materials 1 6 instruments and equipment 3 7 Sample 3

8 Analysis steps

The results are calculated and expressed 10 precision and accuracy Quality assurance and quality control 12 Waste treatment 13 Precautions .7

Foreword

In order to implement the Environmental Protection Law of the People's Republic of China and the Law of the People's Republic of China on the Prevention and Control of Atmospheric Pollution, Protection of human health, regulate the ambient air particles in the determination of hexavalent chromium, the development of this standard. This standard specifies the determination of hexavalent chromium in ambient air particulate matter by ion chromatography. This standard is the first release. This standard is organized by the Ministry of Environmental Protection Science and Technology Standards Division. The main drafting of this standard. China Environmental Monitoring Station, the National Environmental Analysis and Testing Center. The standard verification unit. Beijing Environmental Protection Monitoring Center, Beijing Chaoyang District Environmental Protection Monitoring Station, Tianjin Ring Environmental Monitoring Center, Jiangsu Province Environmental Monitoring Center, Hunan Provincial Environmental Monitoring Center Station, Chongqing Environmental Monitoring Center, Sichuan Province Environmental monitoring terminus. This standard is approved by the Ministry of Environmental Protection on December 4,.2015. This standard has been implemented since January 1,.2016. This standard is explained by the Ministry of Environmental Protection. Determination of hexavalent chromium in ambient air - post - column derivatization ion chromatography WARNING. Potassium dichromate and diphenylcarbonylate used in this method are highly toxic and should be avoided during contact with skin and clothing.

1 Scope of application

This standard specifies the determination of hexavalent chromium in ambient air particulate matter by ion chromatography. This standard is applicable to the determination of hexavalent chromium in ambient air particulate matter. When the sampling volume is 21 m3 (standard state), the volume of the extract is 10 ml and the injection volume is 1 ml. The limit is 0.005 ng/m3 and the lower limit of determination is 0.020 ng/m3.

2 normative reference documents

The contents of this standard refer to the following documents or their terms. Those who do not specify the date of the reference file, the effective version of the appropriate For this standard. Technical specification for manual monitoring of ambient air quality Technical Requirements and Test Methods for HJ 93 Environmental Air Particulate (PM10 and PM2.5) Sampler Determination of ambient air PM10 and PM2.5 by HJ 618

3 Principle of the method

In the ambient air particulate matter, hexavalent chromium present in the form of chromate and dichromate is collected into the finely treated fibers Filter, under alkaline conditions by ultrasonic extraction, anion column separation, and the developer diphenyl carbonyl hydrazine formation The absorbance, absorbance and the concentration of hexavalent chromium in the sample were measured at 530 nm with a UV-visible detector Is proportional to it.

4 interference and elimination

When the ambient air of ferrous iron, nitrite, thiosulfate and other strong reducing ion concentration is high, with hexavalent chromium The occurrence of redox reaction, resulting in negative interference. A higher content of soluble ferric ions may also cause negative interference to the assay. The extraction and determination in the alkaline environment can inhibit the conversion of hexavalent chromium, and can avoid the interference of ferric ions.

5 reagents and materials

Unless otherwise stated, analytical pure chemical reagents are used in accordance with national standards. Experimental water for the resistivity ≥ 18.2 MΩ · cm of deionized water. 5.1 sodium bicarbonate (NaHCO3). excellent grade pure. 5.2 ammonium sulfate. ρ [(NH4) 2SO4] = 1.77 g/ml, excellent grade pure. 5.3 ammonia. ρ (NH3 · H2O) = 0.91 g/ml, excellent grade pure. 5.4 Diphenylcarbazide (C13H14N4O). 5.5 Methanol. ρ (CH3OH) = 0.79 g/ml, HPLC grade, purity greater than 99.9%. 5.6 Sulfuric acid. ρ (H2SO4) = 1.84 g/ml, excellent grade pure. 5.7 potassium dichromate (K2Cr2O7). reference reagent or excellent grade pure. Weigh 5.0 g of potassium dichromate in a porcelain crucible, placed in an oven at 105 ° C for 2 h, cooled to room temperature and placed in a dryer Save, spare. 5.8 Sodium bicarbonate solution. c (NaHCO3) = 0.12 mol/L. Weigh 5.0 g of sodium bicarbonate (5.1), dissolve in water and dilute to 500 ml. 5.9 Sodium bicarbonate solution. c (NaHCO3) = 20 mmol/L. 3.36 g of sodium bicarbonate (5.1) was weighed and dissolved in water and diluted to.2000 ml. 5.10 potassium dichromate stock solution. ρ (Cr (Ⅵ)) = 1000 mg/L. Accurately weighed 0.2829 g potassium dichromate (5.7) dissolved in water, transferred to 100 ml volumetric flask, dilute the volume to the line. You can also purchase a commercially available standard material or a certified standard solution. 5.11 Potassium dichromate solution. ρ (Cr (Ⅵ)) = 10 mg/L. Accurately remove 0.5 ml of potassium dichromate stock solution (5.10) in 50 ml volumetric flask, dilute with sodium bicarbonate solution (5.9) Release the line. 5.12 potassium dichromate standard use of liquid. ρ (Cr (Ⅵ)) = 100 ng/ml. Accurately remove 0.5 ml of potassium dichromate intermediate solution (5.11) in a 50 ml volumetric flask with sodium bicarbonate solution (5.9) Dilute the volume to the mark. 5.13 eluent. 250 mmol/L ammonium sulfate 100 mmol/L ammonium hydroxide. Weigh 66 g of ammonium sulfate (5.2) dissolved in water, add 14 ml of ammonia (5.3), shake, dilute the volume to.2000 ml. Immediately transferred to the eluent bottle, can be added nitrogen protection, to slow down the alkaline eluent to absorb CO2 in the air and failure. 5.14 Derivative reagents Weigh 0.50 g of diphenylcarbazide (5.4), dissolved in methanol (5.5) and diluted to 100 ml with methanol (5.5). Add 28 ml of concentrated sulfuric acid (5.6) slowly to 300 ml of water and dilute to 500 ml. Transfer the diphenylcarbazide solution to methanol Transferred to sulfuric acid aqueous solution, diluted with water to 1000 ml, and transferred to the derivative reagent bottle, can add nitrogen, pressure 6 psi ~ 9 Psi (1 psi = 6.89475 x 103 Pa) to prevent air bubbles from occurring. Need to save the light, save time should not exceed 3 d. 5.15 sampling filter. cellulose material, 47 mm. 5.16 Water-based microporous membrane. pore size 0.22 μm. 5.17 filter box. Teflon (PTFE) or polystyrene (PS) material. 5.18 Nitrogen. Purity ≥99.999%.

6 instruments and equipment

6.1 ambient air particulate sampling equipment. sampling device from the sampling head, sampling pump and flow meter components. Sampling head is equipped with different Cutter can collect TSP, PM10 and PM2.5 particles; flow meter for small flow, range < 30 L/min; flow indication error ≤ 2%; other performance and technical indicators should be consistent with HJ 93 requirements. 6.2 Ion chromatograph. post-column derivator and UV-visible detector. 6.3 Column. Anion separation column (polydiorylene benzene/ethyl vinyl benzene, with alkanol quaternary ammonium functional groups, hydrophilic, High-capacity columns) and anionic guard columns. 6.4 freezer. easy to transfer, the internal temperature below 4 ℃. 6.5 Ultrasonic instrument. 50/60 Hz. 6.6 Glassware. Unless otherwise stated, the use of Class A glassware in accordance with national standards is used for analysis. 6.7 15 ml tube. polypropylene (PP) or polytetrafluoroethylene (PTFE) material, with a screw cap. 6.8 Common laboratory equipment and equipment.

7 samples

7.1 sampling filter preparation The sample filter (5.15) was repeatedly sonicated with sodium bicarbonate solution (5.9), and the remaining sodium bicarbonate in the filter was washed with water. The cleaned filter was immersed in sodium bicarbonate solution (5.8) for 4 h to dry. Samples were sampled within one week after treatment. 7.2 Collection of samples According to the relevant provisions of HJ 618 and HJ/T 194, with the prepared filter (7.1) to collect samples of ambient air particles, Sampling flow rate of 16.7 L/min, sampling time 24 ± 1 h. 7.3 Transport and storage of samples The sample filter (7.2) should be stored in the filter box (5.17) during transport and stored at low temperature in the freezer (6.4) If not timely determination, should be sealed at -18 ℃ frozen storage, measured within 1 week. 7.4 Preparation of sample Place the sample filter in a 15 ml tube (6.7), add 10 ml of sodium bicarbonate solution (5.9), tighten the screw cap, Ultrasonic instrument (6.5) Ultrasound 1 h. The extract was filtered through an aqueous microporous membrane (5.16) and placed in a vial. 7.5 Preparation of laboratory blank samples A blank sample was prepared by sampling the same batch with the sample, and a blank sample was prepared with the preparation step (7.4) of the sample. 7.6 Preparation of full program blank samples Will be collected with the sample batch of blank filter to the sampling site, do not collect particulate samples, according to the sample transport and Save (7.3), go back to the laboratory with the sample, prepare the full program blank sample with the preparation procedure (7.4) of the sample.

8 Analysis steps

8.1 Instrument reference conditions Optimize measurement conditions or parameters according to the instrument manual. Reference conditions. eluent (5.13) flow rate 1 ml/min, column After the derivatization reagent (5.14) flow rate of 0.33 ml/min, mixed pipeline 750 μl, UV visible detector detection wavelength of 530 nm. 8.2 Standard curve drawing Respectively, accurate removal of 0.00 ml, 0.10 ml, 0.20 ml, 0.50 ml, 1.00 ml, 2.00 ml, 5.00 ml of potassium dichromate Quasi-use of liquid (5.12) placed in a group of 100 ml volumetric flask, diluted with sodium bicarbonate solution (5.9) fixed volume to the mark, shake. The concentrations of hexavalent chromium in the standard series were 0.00 ng/ml, 0.10 ng/ml, 0.20 ng/ml, 0.50 ng/ml, 1.00 ng / 2.00 ng/ml, 5.00 ng/ml. According to its concentration from low to high order into the ion chromatograph, measuring the instrument response value and retention The ion chromatogram is shown in Fig. With hexavalent chromium concentration as the abscissa, the corresponding absorbance for the vertical axis, draw the standard curve. Figure 1 hexavalent chromium standard solution ion chromatogram 8.3 Determination of samples The sample (7.4) was injected into an ion chromatograph according to the same chromatographic conditions as the standard curve and step (8.2) Hexavalent chromium concentration, with retention time qualitative, instrument response value quantitative. Note 1. If the concentration of the target compound exceeds the curve, dilution is performed and the dilution factor (DF) is recorded. 8.4 Determination of laboratory blanks The laboratory blank sample (7.5) was injected with ions according to the same chromatographic conditions as the standard curve and procedure (8.2) Chromatography Determination of hexavalent chromium concentration, with retention time qualitative, instrument response quantitative. 8.5 Determination of full program blank The whole program blank sample (7.6) was injected with the same chromatographic conditions and procedure (8.2) as the standard curve for drawing Chromatography Determination of hexavalent chromium concentration, with retention time qualitative, instrument response quantitative.

9 Results calculation and representation

9.1 Results calculation The concentration of hexavalent chromium in ambient air particles is calculated as follows. 0s DF10) ()) VI (( Cr ×× - = ρρρ (1) Where. ρ (Cr (Ⅵ)) - ambient air particles in the mass concentration of hexavalent chromium, ng/m3; S ρ - mass concentration of hexavalent chromium in sample, ng/ml; 0 ρ - mass concentration of hexavalent chromium in blank sample, ng/ml; 10 - sample solution volume, ml; Vn - standard conditions (101.325kPa, 273K) under the sampling volume, m3; DF - dilution factor. 9.2 The result is shown When the mass concentration of hexavalent chromium in ambient air particulate matter is greater than or equal to 0.100 ng/m3, the result is retained. When the number is less than 0.100 ng/m3, the result is retained to 3 digits after the decimal point. 10 precision and accuracy 10.1 Precision 7 laboratory, respectively, on the hexavalent chromium content of 1 ng, 10 ng, 50 ng of the unified blank spiked membrane samples were measured, The relative standard deviations in the laboratory were 3.8% ~ 9.1%, 1.2% ~ 4.5%, 0.9% ~ 2.8%, respectively. The relative standard deviation Respectively, 11.6%, 4.8%, 3.9%, repeatability r were 0.009 ng/m3, 0.039 ng/m3, 0.104 ng/m3, The limit R is 0.017 ng/m3, 0.074 ng/m3, 0.256 ng/m3, respectively. 10.2 Accuracy 7 laboratory, respectively, on the hexavalent chromium content of 1 ng, 5 ng, 20 ng of a unified blank spiked membrane samples were measured, The relative errors in the laboratory were 0.0% ~ 24.0%, 0.4% ~ 10.6%, 0.5% ~ 9.5%, respectively. The relative error between the two -0.24% ~ 15.96%, - 0.21% ~ 7.19%, 1.41% ~ 9.01%. 7 laboratories were collected the actual sample, plus standard back The actual concentration of the sample was 0.035 ng/m3 ~ 0.351 ng/m3, plus the standard volume of 10 ng, the actual sample back The yield was 81.3% ~ 118%. 11 quality assurance and quality control 11.1 Environmental Air Particulate Sampling Equipment (6.1) Flow calibration and air tightness checks are required before each sampling, other qualities Warranty and quality control measures are carried out in accordance with the relevant requirements of HJ/T 194. 11.2 Due to the low detection limit of this method, high purity reagents must be used in standard solution preparation and sample pretreatment to reduce the measurement Set the blank value. 11.3 The correlation coefficient of the standard curve should be greater than or equal to 0.999. Each batch of samples (≤ 20) should be analyzed for a standard Curve of the middle point of the concentration of the standard solution, the determination of the results and the standard curve of the relative error between the point should be ≤ 10%. otherwise, The standard curve should be redrawn. 11.4 each batch of samples should be analyzed at least two laboratory blank samples, laboratory blank determination results should be lower than the lower limit of determination, the level The relative deviation of the two-way measured value should not be greater than 10%. Each analysis of a batch (≤ 10) samples at least do a full program blank Sample, the whole program blank determination results should be lower than the lower limit of determination. Otherwise, the cause should be identified and the sample should be resampled until qualified To determine the sample. 11.5 each batch of samples (≤ 20) at least to do a spike recovery determination, the actual sample spiked recovery should be controlled at 80% to 120%. 12 Waste treatment Potassium dichromate and dibenzoyl hydrazine is highly toxic, the waste and waste generated in the experiment should be collected collectively and properly kept, Commissioned by qualified units for processing. 13 Precautions 13.1 If there is interference with the determination of hexavalent chromium peak, should be based on laboratory needs to adjust the eluent flow rate, so that the interference peak and Target peak separation. 13.2 post-column derivatization process, the pump pressure instability or changes in room temperature generated by the bubble will affect the determination, can be pressurized by nitrogen Protect to reduce the impact. 13.3 The equipment used in the experiment shall not be cleaned by acid soaking, and the polypropylene (PP) or polytetrafluoroethylene (PTFE) material Of the disposable utensils, to avoid the blank value is higher. 13.4 Sampled filters impregnated with sodium bicarbonate solution may cause a decrease in flow during sampling and high performance Of the sampling system. 13.5 Preparation and pretreatment of filters should be carried out in a clean environment to avoid contamination. Conditional laboratory, can be related to the operation For use in a glove box with nitrogen purge. ......

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