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HJ 667-2013 English PDF

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HJ 667-2013: Water quality. Determination of total nitrogen by continuous flow analysis(CFA) and N-(1-naphthyl)ethylene diamine dihydrochloride spectrophotometry
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HJ 667-2013English339 Add to Cart 3 days [Need to translate] Water quality. Determination of total nitrogen by continuous flow analysis(CFA) and N-(1-naphthyl)ethylene diamine dihydrochloride spectrophotometry Valid HJ 667-2013

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Standard similar to HJ 667-2013

GB 5085.7   HJ 694   GB 5085.1   HJ 668   HJ 669   HJ 666   

Basic data

Standard ID HJ 667-2013 (HJ667-2013)
Description (Translated English) Water quality. Determination of total nitrogen by continuous flow analysis(CFA) and N-(1-naphthyl)ethylene diamine dihydrochloride spectrophotometry
Sector / Industry Environmental Protection Industry Standard
Classification of Chinese Standard Z16
Classification of International Standard 13.060
Word Count Estimation 13,145
Quoted Standard HJ/T 91; HJ/T 164
Regulation (derived from) Ministry of Environmental Protection Notice No. 63 of 2013
Issuing agency(ies) Ministry of Ecology and Environment
Summary This standard specifies the determination of total nitrogen continuous flow of water - hydrochloric acid naphthylethylenediamine spectrophotometry. This standard applies to surface water, groundwater measurement, sewage and industrial effluent total nitro

HJ 667-2013: Water quality. Determination of total nitrogen by continuous flow analysis(CFA) and N-(1-naphthyl)ethylene diamine dihydrochloride spectrophotometry


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Water quality.Determination of total nitrogen by continuous flow analysis (CFA) and N-(1-naphthyl)ethylene diamine dihydrochloride spectrophotometry National Environmental Protection Standard of the People's Republic Determination of total nitrogen in water Continuous flow - naphthylamine diamine hydrochloride spectrophotometry Water quality-Determination of total nitrogen by continuous flow Analysis(CFA) and N-(1-naphthyl)ethylene diamine dihydrochloride Published on.2013-10-25 2014-01-01 implementation Ministry of Environmental Protection released

Content

Preface II 1 Scope.1 2 Normative references..1 3 principle of the method.1 4 interference and elimination..2 5 reagents and materials..2 6 instruments and equipment..3 7 samples..3 8 Analysis steps.3 9 result calculation and representation..4 10 precision and accuracy..4 11 Quality Assurance and Quality Control.5 12 Notes.6 Appendix A (informative) Persulfate purification method.7 Appendix B (informative appendix) Method for activation and filling of cadmium particles 8

Foreword

To protect the environment and protect the "Environmental Protection Law of the People's Republic of China" and the Law of the People's Republic of China on Water Pollution Prevention Human health, standardizing methods for determining total nitrogen in water, and developing this standard. This standard specifies the continuous flow of total nitrogen in water - naphthylethylenediamine hydrochloride spectrophotometry. This standard is the first release. Appendix A and Appendix B of this standard are informative annexes. This standard was formulated by the Science and Technology Standards Department of the Ministry of Environmental Protection. This standard is mainly drafted by. Suzhou Environmental Monitoring Center Station. This standard is verified by. Jiangyin Environmental Monitoring Station, Taihu Basin Water Environment Monitoring Center, Jilin City Environmental Protection Monitoring Station, Tian Tianjin Water Environment Monitoring Center, Yellow River Basin Water Environment Monitoring Center, Suzhou Environmental Monitoring Center Station. This standard was approved by the Ministry of Environmental Protection on October 25,.2013. This standard has been implemented since January 1,.2014. This standard is explained by the Ministry of Environmental Protection. Determination of total nitrogen in water - Continuous flow - Naphthylethylenediamine hydrochloride spectrophotometric method

1 Scope of application

This standard specifies the continuous flow of total nitrogen in water - naphthylethylenediamine hydrochloride spectrophotometry. This standard applies to the determination of total nitrogen in surface water, groundwater, domestic sewage and industrial wastewater. When the detection optical path is 30mm, the detection limit of this method is 0.04mg/L (in N), and the measurement range is 0.16 mg/L. ~10mg/L.

2 Normative references

The contents of this standard refer to the terms in the following documents. For undated references, the valid version applies to this standard. HJ/T 91 Surface Water and Wastewater Monitoring Technical Specifications HJ/T 164 Technical Specifications for Groundwater Environmental Monitoring

3 Principle of the method

3.1 Working principle of continuous flow analyzer The sample and the reagent enter the chemical reaction module under the push of the peristaltic pump, and continuously flow in the closed pipeline, and are pressed by the bubble. They are regularly spaced at regular intervals and mixed and reacted in a specific order and proportion. After the color development is completed, they enter the flow detection cell. Photometric detection. 3.2 Principles of chemical reactions In an alkaline medium, the nitrogen-containing compound in the sample is oxidized by persulfate at 107 ° C to 110 ° C under ultraviolet irradiation. After the nitrate, it is reduced to nitrite by a cadmium column. In an acidic medium, nitrite is diazotized with sulfonamide and then with salt The acid naphthyl ethylenediamine was coupled to form a purple-red compound, and the absorbance was measured at a wavelength of 540 nm. Refer to the work flow chart, as shown in Figure 1. 1 peristaltic pump 2 heating bath 107 ° C ~ 110 ° C 3 UV digestion device 4 mixed reaction ring 5 dialyzer (unit) 6 cadmium column 7 bubble removal 8 flow detection cell 30mm 540nm R1 potassium persulfate solution (5.15) 0.32ml/min R2 sodium tetraborate buffer solution (5.16) 0.42ml/min R3 Ammonium chloride buffer solution (5.18) 0.80ml/min, 1.40ml/min R4 Color reagent (5.19) 0.23ml/min S sample 1.00ml/min ReS secondary injection 0.32ml/min G air W waste liquid Figure 1 Flow chart of continuous flow-naphthylethylenediamine hydrochloride spectrophotometric determination of total nitrogen

4 interference and elimination

4.1 When the concentration of ferric ion, hexavalent chromium ion and chloride ion in the sample are greater than 180mg/L, 50mg/L and 5000mg/L respectively At the time of the measurement, the total nitrogen is negatively interfered; the high concentration of organic matter consumes potassium persulfate oxidant, and the water-like chromium method has a large COD value. At 400 mg/L, the total nitrogen measurement results are low. The above interference can be eliminated by diluting the sample, but it is necessary to pass multiple dilutions. Confirmation of the consistency of the results of the measurement or the addition of the standard. 4.2 The turbidity or chromaticity of the sample interferes with the measurement results and can be eliminated by the dialysis unit, see Figure 1. 4.3 When the sample contains more solid particles or suspended solids, it should be shaken, sampled, diluted properly, and homogenized. After injection.

5 reagents and materials

Analytical purification reagents that meet national standards were used for analysis unless otherwise stated. The experimental water is freshly prepared, Ammonia-free water with a resistivity greater than 10 MΩ·cm (25 ° C). 5.1 Sulfuric acid. ρ(H2SO4) = 1.84 g/ml. 5.2 Phosphoric acid. ρ(H3PO4) = 1.69 g/ml. 5.3 Ammonia. ρ(NH4OH) = 0.90 g/ml. 5.4 Sodium hydroxide (NaOH). 5.5 Potassium persulfate (K2S2O8). 5.6 Sodium tetraborate (Na2B4O7·10H2O). 5.7 Ammonium chloride (NH4Cl). 5.8 Dodecyl polyglycol ether (Brij35, C58H118O24). 5.9 Sulfonamide (C6H8N2O2S). 5.10 Naphthylethylenediamine hydrochloride (C12H16Cl2N2). 5.11 Potassium nitrate (KNO3). excellent grade, dried at 105 ± 5 ° C °C and stored in a desiccator. 5.12 Potassium nitrite (KNO2). 5.13 Glycine (glycine, H2NCH2COOH). Store in a cool place. 5.14 sodium hydroxide solution. c (NaOH) = 5mol/L Weigh.200g of sodium hydroxide (5.4) dissolved in water and dilute to 1L. 5.15 potassium persulfate solution. ρ (K2S2O8) = 49g/L. Weigh 49 g of potassium persulfate (5.5) dissolved in 800 ml of water and dilute to 1 L. The solution is stored at room temperature and is stable for 1 month. 5.16 sodium tetraborate buffer solution. Weigh 38g sodium tetraborate (5.6) dissolved in 800ml water, add 30ml sodium hydroxide solution (5.14), dilute with water to 1L, mix well. The solution is stored at room temperature and is stable for 1 month. 5.17 Dodecyl polyglycol ether (Brij35) solution. ω = 30% 30 g of Brij35 (5.8) was weighed and dissolved in 100 ml of water. 5.18 Ammonium chloride buffer solution. pH=8.2 Weigh 50g ammonium chloride (5.7) dissolved in 800ml water, adjust the pH to 8.2 with ammonia water (5.3), dilute to 1L with water, add Add 3 ml of Brij35 solution (5.17) and mix. The solution was stored at 4 ° C and the pH was checked every 2 to 3 days. 5.19 color reagent Measure 150 ml of phosphoric acid (5.2) dissolved in 100 ml of water, add 10 g of sulfonamide (5.9) and 0.5 g of naphthylethylenediamine hydrochloride (5.10). Dilute to 1 L with water and in a brown bottle. The solution was stored at 4 ° C and was stable for 1 month. But if you find the color of the solution Turns pink and should be deactivated immediately. 5.20 Potassium nitrate standard stock solution. ρ(N)=1000mg/L Weigh 7.218g potassium nitrate (5.11), dissolve in water, transfer to a 1000ml volumetric flask, dilute to volume with water and mix well. In the reagent bottle. The solution is stored in the dark at 4 ° C for at least 6 months. 5.21 Potassium nitrate standard use solution. ρ(N)=10.00mg/L Accurately measure 10.00ml of potassium nitrate standard stock solution (5.20), transfer to a 1000ml volumetric flask, dilute to volume with water and mix. Available at the time of use. 5.22 Glycine standard stock solution. ρ(N)=1000mg/L Weigh 5.360g of glycine (5.13), dissolve in water, transfer to a 1000ml volumetric flask, dilute to volume with water, and mix. In a brown bottle. The solution is stored in a sealed container at 4 ° C for at least 3 months. 5.23 Glycine standard use solution. ρ (N) = 10.00 mg/L Accurately measure 10.00ml of aminoacetic acid stock solution (5.22), transfer to a 1000ml volumetric flask, dilute to volume with water and mix. Available at the time of use. 5.24 Potassium nitrite standard stock solution. ρ(N)=1000mg/L Weigh 6.079g of potassium nitrite (5.12), dissolve in water, transfer to a 1000ml volumetric flask, dilute to volume with water, and mix. In a brown bottle. The solution is stored in a sealed container at 4 ° C for at least 1 month. 5.25 Standard use solution of potassium nitrite. ρ(N)=10.0mg/L Accurately measure 10.0ml of potassium nitrite stock solution (5.24), transfer to a 1000ml volumetric flask, dilute to volume with water and mix. Available at the time of use. 5.26 Cleaning solution (sodium hypochlorite solution). A suitable amount of a commercially available sodium hypochlorite (NaClO) solution was weighed and diluted with water to a solution having an effective chlorine content of about 1.3%.

6 Instruments and equipment

6.1 Continuous Flow Analyzer. Autosampler (with homogenous components), chemical analysis unit (ie chemical reaction module, by multiple Channel peristaltic pump, manifold, pump tube, mixed reaction ring, UV digestion device, dialyzer, cadmium column, heating pool, etc.) Measuring unit (flow detection cell optical path is 30mm), data processing unit. 6.2 Balance. The accuracy is 0.0001g. 6.3 pH meter. accuracy is 0.02. 6.4 Common instruments and equipment used in general laboratories.

7 samples

Samples were collected and stored in accordance with the relevant regulations of HJ/T 91 and HJ/T 164. Wash all containers that contact the sample with water before sampling. Collect samples in polyethylene or glass bottles with sulfuric acid (5.1) Acidified to pH ≤ 2, can be stored for 7 days at room temperature, or collected in a polyethylene bottle, frozen at -20 ° C, can be stored for 1 month.

8 Analysis steps

8.1 Commissioning of the instrument Install the analysis system, set the operating parameters, and operate the instrument according to the instrument manual. After starting the machine, first replace the reagent with water, check Check the tightness of the flow path and the smoothness of the liquid flow. After the baseline is stabilized (about 20 min), the system starts to enter the reagent. After the baseline is stabilized again, proceed to 8.2~8.4. 8.2 Calibration 8.2.1 Preparation of the calibration series A suitable amount of potassium nitrate standard stock solution (5.20) was weighed and diluted stepwise to prepare a standard series of 6 concentration points. Total nitrogen The concentrations were. 0.00 mg/L, 0.20 mg/L, 1.00 mg/L, 3.00 mg/L, 5.00 mg/L, and 10.0 mg/L. 8.2.2 Drawing of the calibration curve The appropriate amount of standard series solution (8.2.1) was separately weighed and placed in the sample cup, and the sampler was sequentially sampled and measured according to the procedure. Taking the measured signal value (peak height) as the ordinate, the corresponding total nitrogen mass concentration (in N, mg/L) is plotted on the abscissa. Quasi-curve. 8.3 Determination The measurement of the sample was carried out under the same conditions as in the drawing of the calibration curve. Note. If the total nitrogen content of the sample exceeds the calibration curve detection range, the appropriate amount of sample should be diluted and measured on the machine. 8.4 Blank test Replace the sample with experimental water and perform a blank test in accordance with step 8.3.

9 Calculation and representation of results

9.1 Calculation of results The mass concentration of total nitrogen (in N, mg/L) in the sample was calculated according to formula (1). Yaf ρ −= × (1) In the formula. Ρ--the mass concentration of total nitrogen in the sample, mg/L; y -- determine the signal value (peak height); a -- the intercept of the calibration curve equation; b -- the slope of the calibration curve equation; f -- dilution factor. 9.2 Results representation When the measurement result is less than 1.00 mg/L, the result is retained to the second decimal place; when it is greater than or equal to 1.00 mg/L, the result Keep three significant digits. 10 Precision and accuracy 10.1 Precision Six laboratories tested uniform samples with total nitrogen concentrations of 1.00 mg/L, 5.00 mg/L, and 9.00 mg/L. The relative standard deviations in the laboratory are. 0.5% to 9.6%, 0.5% to 4.0%, and 0.4% to 2.2%; the relative standard between laboratories The deviations were. 4.2%, 2.3% and 1.6%; the repeatability limits were. 0.13mg/L, 0.30mg/L, 0.34mg/L; The sexual limits were. 0.17 mg/L, 0.42 mg/L, and 0.52 mg/L, respectively. 10.2 Accuracy 6 laboratories have certified standard substances with total nitrogen concentrations of 0.50 mg/L ± 0.06 mg/L and 2.99 mg/L ± 0.16 mg/L, respectively. For the determination, the relative errors are. 0.0%~3.6%, 0.7%~4.0%; the relative error final values are. 1.5%±2.8%, 2.5% ± 2.6%. The total nitrogen concentration in the six laboratories was 0.21 mg/L ~ 2.86 mg/L, 3.18 mg/L ~ 5.12 mg/L, and 3.06 mg/L, respectively. The three actual samples of ~8.85 mg/L were spiked and recovered. The recoveries were 92.0%~111% and 93.2%~105%. 96.0%~110%; the final values of the spiked recovery were. 101%±15%, 98.4%±9.0%, 102%±12.2%. 11 Quality Assurance and Quality Control 11.1 Blank test At least 2 blank samples shall be measured for each batch of samples, and the blank value shall not exceed the method detection limit. Otherwise, you should find out the reason and re The sample can only be determined after analysis until it is qualified. 11.2 Calibration validity check A calibration curve must be drawn for each batch of samples. The correlation coefficient of the calibration curve is γ ≥ 0.995. For each sample analyzed, a calibration curve intermediate concentration solution shall be used for calibration verification, and the measurement results are relatively biased. The difference should be ≤ 5%, otherwise the calibration curve should be redrawn. 11.3 Precision Control At least 10% of the parallel samples should be determined for each batch of samples. When the number of samples is less than 10, at least one parallel sample should be determined. When the total nitrogen concentration of the sample is ≤1.00mg/L, the allowable relative deviation of the parallel sample should be ≤10%; when the total nitrogen concentration is >1.00mg/L, The allowable relative deviation of parallel samples should be ≤ 5%. 11.4 Accuracy Control At least 10% of the spiked samples shall be determined for each batch of samples. When the number of samples is less than 10, at least one spiked sample shall be determined. Product, the standard recovery rate should be between 80~120%. If necessary, each batch of samples shall have at least one QC sample of known concentration, and the test results shall be within the range of uncertainty given by it. Inside. 11.5 System Performance Check 11.5.1 UV digestion efficiency test UV digestion efficiency will decay with time of use, and the standard use solution of aminoacetic acid should be measured periodically to verify the elimination efficiency of the method. rate. It is usually checked once every 3 months. First calibrate the system (8.2), then parallel determination of the aminoacetic acid standard use solution (5.23) and potassium nitrate standard use solution (5.21). The digestion efficiency R is calculated according to the formula (2). R should be greater than 90%. 100%R ρρ= × (2) In the formula. R - digestion efficiency, %; Ρ1--aminoacetic acid standard use solution (5.23) determination results, mg/L; Measured results of ρ2--potassium nitrate standard use solution (5.21), mg/L. 11.5.2 Inspection of cadmium column reduction ability When the color of the cadmium column is found to be silvery gray or white precipitate, the cadmium column reduction ability test is required. Turn off purple in the test The lamp is replaced with water and potassium persulfate solution (5.15). According to the same procedure as the sample determination, the nitrogen content is measured separately. The potassium nitrite standard use solution (5.25) and the potassium nitrate standard use solution (5.21). If the latter determines the result than the former If it is lower than 10%, the cadmium column needs to be replaced. It is usually checked once a month. See Appendix B for methods of activation and filling of cadmium particles. Note. When the measured result of the certified reference material is lower than the lower limit of its uncertainty range, 11.5.1 and 11.5.2 are required. 12 Precautions 12.1 The nitrogen content of the main reagent potassium persulfate will affect the analytical results. When the reagent baseline is 20% higher than the water baseline, the calibration curve is low When the relative error of the concentration point (0.20mg/L) is greater than 20%, the potassium persulfate needs to be purified. See Appendix A for the purification method. Determination In the case of total nitrogen, various reagents must be prepared without ammonia water. The various acids and acid solutions used must be covered in time to prevent ammonia gas from entering. In. 12.2 To reduce baseline noise, the reagents should be kept clear and the reagents should be filtered if necessary. Reagents and ambient temperature will affect the analytical junction If the reagent stored in the refrigerator needs to be placed at room temperature before use, the room temperature fluctuation during the analysis should not exceed ±5 °C. Potassium persulfate Digestion solution and sodium tetraborate buffer solution are easy to crystallize at low temperature. In order to prevent solute precipitation from clogging the pipeline, it is recommended that these two reagents not be placed. refrigerator. 12.3 Take care to protect the cadmium column and filter. After the system is cleaned, the cadmium column should be cut off in time to avoid air ingress; after the analysis is completed, The filter in the flow detection cell (see Figure 1) should be removed in time to put it into the dryer to prevent dust and moisture. 12.4 Pay attention to the cleaning of the flow path. After the analysis is completed every day, all the flow paths should be washed with water for 30 minutes. Weekly cleaning solution (5.26) The line was cleaned for 30 min and then washed with water for 30 min. When cleaning the system with a cleaning solution, the cadmium column flow path should be cut off (offline). Wash again. 12.5 The dialysis membrane should be kept moist. To prevent the dialysis membrane from rupturing, it can be added per liter of cleaning water when cleaning the analytical piping system. 1 drop of Brij35 (5.17). 12.6 When the concentration of the sample analyzed in the same batch fluctuates greatly, a blank can be inserted between the sample and the sample as the sample is analyzed to reduce the height. The effect of concentration samples on low concentration samples. 12.7 Different types of flow analyzers can be selected with reference to this standard to select the appropriate instrument conditions.

Appendix A

(informative appendix) Persulfate purification method A.1 Reagents and equipment A.1.1 Potassium persulfate. A.1.2 Filter paper or sand core funnel (G2). A.1.3 Beaker. A.1.4 Dryer. A.2 Operation steps Weigh 100 g of potassium persulfate (A.1.1) into a beaker and dissolve it with 500 ml of ammonia-free water at 70 ° C to 80 ° C. Solution After naturally cooling to room temperature, it is placed in an ice water bath for 45 min to 60 min. Filter with filter paper or sand core funnel (G2), will The recrystallized potassium persulfate is dried in a desiccator. Repeat as necessary. Note. The entire purification process should avoid ammonia pollution in the environment; filter paper or core funnel should be washed with ammonia-free water before use.

Appendix B

(informative appendix) Cadmium particle activation and filling method B.1 reagent B.1.1 Hydrochloric acid solution, c (HCl) = 4 mol/L. B.1.2 Copper sulfate solution, ω (CuSO4) = 2%. B.2 Operation steps B.2.1 Activation of cadmium particles The cadmium particles were screened for about 10 min using a 18 mesh and 40 mesh sieve. Put the cadmium particles in a 40 mesh sieve into a beaker and add hydrochloric acid. Liquid (B.1.1) until the cadmium particles were completely covered and stirred with a glass rod for about 1 min. The acid is then poured out. Distilled water was added until the cadmium particles were completely covered, stirred vigorously with a glass rod, and then the water was poured out. Repeat this operation multiple times, Until the acid is washed. Check the pH of the cadmium washing water. When it is neutral, perform the following steps. Add copper sulfate solution (B.1.2) until the cadmium particles are completely covered and stir vigorously with a glass rod. The cadmium color changes to black. The copper sulfate solution was decanted, washed twice with distilled water, and the dirt on the cadmium particles was rinsed off. Control the cadmium on the filter paper, Heat and dry at 60 ° C for use. B.2.2 Filling of cadmium particles The cadmium particles are placed in a dry cadmium column with a funnel. When loading the column, the two ends of the column should be shaken continuously to make the cadmium particles in close contact. Cadmium Fill it 5mm from the top of the column and insert a small piece of sharpened polyethylene tube into the entrance of the column to prevent cadmium particles from leaking out. Note The emitter is injected with a buffer solution of ammonium chloride (5.18) into the cadmium column, and there are no bubbles in the column. Load the cadmium column into the analysis module and set aside. Note 1. Avoid air entering the cadmium column; the activated cadmium particles can be stored in a dry, closed bottle. Note 2. Cadmium particles are toxic and should be avoided in contact with eyes and skin. Note 3. The waste cadmium column is treated as hazardous waste.

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