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HJ 1191-2021 English PDF

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HJ 1191-2021: (Water quality Determination of azide spectrophotometric method)
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Standard similar to HJ 1191-2021

HJ 1199 HJ 1200 HJ 1198

Basic data

Standard ID	HJ 1191-2021 (HJ1191-2021)
Description (Translated English)	(Water quality Determination of azide spectrophotometric method)
Sector / Industry	Environmental Protection Industry Standard
Word Count Estimation	9,941
Issuing agency(ies)	Ministry of Ecology and Environment

HJ 1191-2021: (Water quality Determination of azide spectrophotometric 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.
(Water quality Determination of azide spectrophotometric method) National Ecological Environment Standard of the People's Republic of China Spectrophotometric method for the determination of azide in water Water quality-Determination of azide-Spectrophotometry This electronic version is the official standard text, which is reviewed and typeset by the Environmental Standards Institute of the Ministry of Ecology and Environment. Posted on 2021-09-17 2022-04-01 Implementation Released by the Ministry of Ecology and Environment directory Foreword...ii 1 Scope...1 2 Normative references...1 3 Terms and Definitions...1 4 Principles of the method...1 5 Interference and cancellation...1 6 Reagents and materials...2 7 Instruments and equipment...2 8 Samples...3 9 Analysis steps...4 10 Result calculation and representation...4 11 Accuracy...5 12 Quality Assurance and Quality Control...6 13 Waste Disposal...6 14 Notes...6 Spectrophotometric method for the determination of azide in water Warning. The sodium azide used in the experiment is a highly toxic reagent and is explosive; hydrochloric acid is highly volatile and corrosive; ferric perchlorate Strong oxidizing and corrosive. Reagent preparation and sample pretreatment should be carried out in a fume hood, and protective gear should be worn as required during operation. Avoid inhalation into respiratory tract or contact with skin and clothing.

1 Scope of application

This standard specifies a spectrophotometric method for the determination of azides in water. This standard applies to the determination of azide in surface water, groundwater, domestic sewage and industrial wastewater. When the sampling volume is 150 ml, the sample preparation volume is 100 ml, and the 10 mm pathlength cuvette is used, the detection limit of the method is 0.08 mg/L (calculated as azide root), the lower limit of determination is 0.32 mg/L (calculated as azide root).

2 Normative references

This standard refers to the following documents or clauses thereof. For dated references, only the dated version applies to this standard. For undated references, the latest edition (including all amendments) applies to this standard. HJ/T 91 Technical Specification for Surface Water and Sewage Monitoring HJ 91.1 Technical Specification for Wastewater Monitoring HJ 164 Technical Specification for Groundwater Environmental Monitoring

3 Terms and Definitions

The following terms and definitions apply to this standard. 3.1 azide Under the conditions specified in this standard, azide compounds of azide acid can be formed by heating and distillation, calculated as azide radicals.

4 Principles of the method

The azide in the sample is heated and converted into azide acid in an acidic medium, which is distilled out with water vapor and absorbed by sodium hydroxide solution. The root ion reacts with ferric ion to form a brown-red complex, and its absorbance is measured at 454 nm. Within a certain concentration range, its absorption The luminosity is proportional to the azide ion content.

5 Interference and cancellation

5.1 The interference of chromaticity, CN-, SCN-, sulfide and common metal ions in the sample can be effectively removed by heating distillation. 5.2 Presence of NO2 in the sample -, it interferes with the determination of azide, which can be eliminated by adding ammonium sulfamate before distillation. 5.0 ml Ammonium Sulfamate The solution (6.12) can eliminate 25.0 mg/L of NO2 -interference.

6 Reagents and Materials

Unless otherwise stated, analytical reagents that meet national standards were used in the analysis, and the experimental water was freshly prepared deionized water or distilled water. 6.1 Hydrochloric acid (HCl). ρ=1.19 g/ml. 6.2 Sodium Hydroxide (NaOH). 6.3 Ferric perchlorate [Fe(ClO4)3·H2O]. chemically pure. 6.4 Sodium azide. w(NaN3)≥99.5%. 6.5 Ammonium sulfamate (NH4SO3NH2). 6.6 Sodium hydroxide solution. ρ(NaOH)=40 g/L. Weigh 20.00 g of sodium hydroxide (6.2), dissolve with a small amount of water, dilute to 500 ml, and store in a polyethylene bottle. 6.7 Sodium hydroxide solution. ρ(NaOH)=400 mg/L. Weigh 0.40 g of sodium hydroxide (6.2), dissolve it with a small amount of water, dilute it to 1000 ml, and store it in a polyethylene bottle. 6.8 Sodium hydroxide solution. ρ(NaOH)=40 mg/L. Measure 100 ml of sodium hydroxide solution (6.7), dilute to 1000 ml with water, and store in a polyethylene bottle. 6.9 Hydrochloric acid solution. c(HCl)=1.0 mol/L. Measure 9.0 ml of hydrochloric acid (6.1), dilute it with water to 100 ml, and store it in a ground glass bottle. 6.10 Hydrochloric acid solution. c(HCl)=0.1 mol/L. Measure 10.0 ml of hydrochloric acid solution (6.9), dilute to 100 ml with water, and store in a ground-mouth glass bottle. 6.11 Ferric perchlorate solution. ρ[Fe(ClO4)3·H2O]=50 g/L. Weigh 5.00 g of ferric perchlorate (6.3), dissolve with 20 ml of hydrochloric acid solution (6.10), transfer to a 100 ml volumetric flask and dilute with water Make up to the mark, shake well, and store in a brown ground glass bottle. Refrigerated below 4 ℃ and protected from light can be stored for 3 months. 6.12 Ammonium sulfamate solution. ρ(NH4SO3NH2)=150 g/L. Weigh 15.00 g of ammonium sulfamate (6.5), dissolve it in a small amount of water, transfer it to a 100 ml volumetric flask, dilute it to the mark, and shake well. Ready to use. 6.13 Standard stock solution of sodium azide. ρ(N3 )=1.00 g/L. Accurately weigh 0.1548 g of sodium azide (6.4), dissolve it with a small amount of sodium hydroxide solution (6.8), transfer it to a 100 ml volumetric flask and Dilute to the mark with sodium hydroxide solution (6.8), shake well, and store in a polyethylene bottle. Refrigerated below 4 ℃ and protected from light can be stored for 3 months. 6.14 Standard solution of sodium azide. ρ(N3 )=25.0 mg/L. Pipette 2.50 ml sodium azide standard stock solution (6.13) into a 100 ml volumetric flask, dilute it with sodium hydroxide solution (6.8) to Line, shake. Ready to use. 6.15 Glass beads. 4 mm to 6 mm in diameter.

7 Instruments and equipment

Unless otherwise stated, the A-grade glass measuring apparatus in accordance with national standards was used in the analysis. 7.1 Sampling bottle. 500 ml amber glass bottle. 7.2 Spectrophotometer. equipped with 10 mm optical path cuvettes. 7.3 Electric furnace. power 0 W ~ 1000 W, adjustable. 7.4 Distillation device. It consists of an all-glass still (with a 500 ml distillation flask and a condenser), a receiving flask and a distillate conduit. 7.5 Receiving bottle. 100 ml colorimetric tube with stopper. 7.6 Colorimetric tube with stopper. 10 ml. 7.7 Common laboratory instruments and equipment.

8 samples

8.1 Sample Collection Collect the sample in the sampling bottle (7.1) according to the relevant regulations of HJ/T 91, HJ 91.1 and HJ 164, and the sample volume is not less than 500 ml. 8.2 Sample Storage After sample collection, add an appropriate amount of sodium hydroxide solution (6.6) to adjust the pH value of the sample to 9-11, store it at room temperature in the dark, and finish it within 3 days. into analysis. 8.3 Preparation of test specimens Measure 150 ml of sample, transfer it into a distillation flask, add 5.0 ml of ammonium sulfamate solution (6.12), put in several glass beads (6.15), Insert the distillate catheter into the receiving bottle (7.5) containing 10.0 ml of sodium hydroxide solution (6.7), making sure that the catheter is submerged below the liquid surface. Open Condensate the water, add 2.0 ml of hydrochloric acid solution (6.9) to the distillation flask, and quickly close the stopper of the distillation flask. Turn on the electric furnace (7.3), adjust the power rate, slowly raise the temperature, control the distillate to distill out at a rate of 2 ml/min to 3 ml/min, and stop when the distillate in the receiving bottle is close to 100 ml heating. Rinse the distillate conduit with a small amount of water, pour it into the receiving bottle, and make up to 100 ml for testing. The distillation process is controlled within 30 min to 45 min appropriate. The schematic diagram of the apparatus is shown in Figure 1. 8.4 Preparation of blank samples Replace the sample with experimental water, add an appropriate amount of sodium hydroxide solution (6.6) to adjust the pH of the sample to 9-11, according to the preparation of the sample (8.3) The same procedure is used for the preparation of laboratory blank samples.

9 Analysis steps

9.1 Establishment of standard curve Take 6 stoppered colorimetric tubes (7.6), add 0.00 ml, 0.20 ml, 0.80 ml, 2.00 ml, 4.00 ml, 6.00 ml of azide respectively Sodium standard use solution (6.14), immediately add sodium hydroxide solution (6.8) to 10.0 ml, and prepare the azide mass concentration of 0.00 mg/L, Standard series solutions of 0.50 mg/L, 2.00 mg/L, 5.00 mg/L, 10.0 mg/L, 15.0 mg/L. Add 0.5 ml to each colorimetric tube Ferric perchlorate solution (6.11), close the stopper tightly and shake well. At a wavelength of 454 nm, using a 10 mm optical path cuvette, with water as a reference, measure The absorbance of each standard series solution was measured, and the measurement was completed within 20 min. Take the mass concentration (mg/L) of azide in each standard series solution as The abscissa is the ordinate, and the absorbance corresponding to the reagent blank (zero concentration) is taken as the ordinate, and a standard curve is established. Note. The color reaction is carried out at room temperature, above 40 ℃ will affect the determination. 9.2 Sample Determination Pipette 10.0 ml of the sample (8.3) into a stoppered colorimetric tube (7.6), and follow the same steps as for establishing a standard curve (9.1). Determination of samples. Note. If the determination result exceeds the highest concentration point of the standard curve, the sample should be diluted and the sample should be re-prepared according to the steps of sample preparation (8.3). 9.3 Blank test Carry out the determination of the laboratory blank sample (8.4) following the same procedure as for the determination of the sample (9.2). 10 Result calculation and presentation 10.1 Result calculation The mass concentration (mg/L) of azide (calculated as azide) in the sample is calculated according to formula (1). 10.2 Result representation The number of decimal places of the determination results is consistent with the detection limit, and a maximum of 3 significant figures are reserved. 11 Accuracy 11.1 Precision Blank spiking of azide (as azide) at 0.50 mg/L, 4.00 mg/L and 8.00 mg/L by six laboratories The samples were repeatedly determined for 6 times. the relative standard deviations in the laboratory were 2.0%-9.5%, 0.9%-5.0% and 0.4%-3.7%, respectively; The inter-laboratory relative standard deviations were 4.2%, 2.2% and 2.5%, respectively; the repeatability limits were 0.08 mg/L, 0.34 mg/L and 0.45 mg/L, respectively; The reproducibility limits were 0.09 mg/L, 0.40 mg/L and 0.67 mg/L, respectively. Surface water samples spiked with azide (as azide) at concentrations of 0.50 mg/L, 4.00 mg/L and 8.00 mg/L by six laboratories The samples were tested 6 times repeatedly. the relative standard deviations in the laboratory were 3.6%-7.7%, 1.0%-5.5% and 0.6%-3.3%, respectively; The inter-chamber relative standard deviations were 6.0%, 2.8%, and 2.4%, respectively; the repeatability limits were 0.08 mg/L, 0.33 mg/L, and 0.56 mg/L, respectively; The limit of detection was 0.11 mg/L, 0.43 mg/L and 0.76 mg/L, respectively. Groundwater samples spiked with azide (as azide) at concentrations of 0.50 mg/L, 4.00 mg/L and 8.00 mg/L by six laboratories The samples were tested 6 times repeatedly. the relative standard deviations in the laboratory were 2.3%-9.9%, 1.0%-3.7% and 0.5%-4.0%, respectively; The inter-chamber relative standard deviations were 5.8%, 3.6%, and 2.0%, respectively; the repeatability limits were 0.08 mg/L, 0.24 mg/L, and 0.49 mg/L, respectively; The limit of detection was 0.10 mg/L, 0.44 mg/L and 0.63 mg/L, respectively. Six laboratories added azide (calculated as azide) to domestic sewage with concentrations of 0.50 mg/L, 4.00 mg/L and 8.00 mg/L The samples were repeatedly determined for 6 times. the relative standard deviations in the laboratory were 4.2%-10.3%, 0.5%-4.7% and 0.4%-4.2%, respectively; The interlaboratory relative standard deviations were 5.8%, 3.4% and 2.6%, respectively; the repeatability limits were 0.08 mg/L, 0.25 mg/L and 0.48 mg/L, respectively; The reproducibility limits were 0.10 mg/L, 0.43 mg/L and 0.71 mg/L, respectively. The average concentration of azide (calculated as azide root) in the six laboratories was 1.31 mg/L, and the standard concentration was 0.50 mg/L and 4.00 mg/L. and 8.00 mg/L industrial wastewater spiked samples were determined repeatedly for 6 times. the relative standard deviations in the laboratory were 2.2%-8.8%, 0.9%-6.9%, 0.7%-5.9% and 0.5%-3.2%; the relative standard deviations among laboratories were 9.1%, 6.6%, 1.7% and 1.4%, respectively; The repeatability limits were 0.17 mg/L, 0.18 mg/L, 0.45 mg/L and 0.45 mg/L, respectively; the reproducibility limits were 0.37 mg/L, 0.37 mg/L, 0.48 mg/L and 0.54 mg/L. 11.2 Correctness Surface water samples spiked with azide (as azide) at concentrations of 0.50 mg/L, 4.00 mg/L and 8.00 mg/L by six laboratories The samples were subjected to 6 repeated standard addition analysis and determination. the standard addition recoveries were 90.0% to 104%, 91.0% to 98.5% and 92.2% to 98.8%, respectively; The final values of the spiked recoveries were 98.3%±12%, 96.3%±5.6% and 96.6%±4.8%, respectively. Groundwater samples spiked with azide (as azide) at concentrations of 0.50 mg/L, 4.00 mg/L and 8.00 mg/L by six laboratories The samples were subjected to 6 repeated standard addition analysis and determination. the standard addition recoveries were 88.0%-102%, 89.0%-102% and 93.4%-99.1%, respectively; The final values of the spiked recoveries were 94.3%±12%, 95.8%±7.2% and 96.8%±4.0%, respectively. Six laboratories added azide (calculated as azide) to domestic sewage with concentrations of 0.50 mg/L, 4.00 mg/L and 8.00 mg/L The samples were subjected to 6 repeated standard addition analysis and determination. the standard addition recoveries ranged from 88.0% to 98.0%, 90.5% to 99.0% and 92.5% to 92.5% to 92.5%. 99.4%; the final recovery of standard addition was 90.3%±12%, 95.5%±6.8% and 95.7%±5.2%, respectively. The average concentration of azide (calculated as azide root) in the six laboratories was 1.31 mg/L, and the standard concentration was 0.50 mg/L and 4.00 mg/L. and 8.00 mg/L industrial wastewater fortified samples were subjected to 6 repeated standard addition analysis and determination. the recovery rates of the standard addition ranged from 88.0% to 96.0%, respectively. 94.5%～98.0% and 93.0%～98.9%, the final recovery of standard addition was 93.0%±6.6%, 96.3%±2.4% and 96.4%±4.4%, respectively. 12 Quality Assurance and Quality Control 12.1 A standard curve should be established for each batch of sample analysis, and the correlation coefficient of the standard curve should be greater than or equal to 0.999. 12.2 At least one set of parallel samples should be determined for every 20 samples or batches of samples (≤20 samples/batch), and the relative deviation of the measurement results should be within ±20% within. 12.3 At least one matrix spiked sample should be determined for every 20 samples or each batch of samples (≤20 samples/batch), and the spiked recovery rate should be between 75% and 75%. between 115%. 13 Waste Disposal The waste liquid generated in the experiment should be collected by classification, stored in a centralized manner, and marked accordingly, and entrust a qualified unit to deal with it according to law. 14 Notes Sodium azide is highly toxic and dangerous, and it is easy to explode under strong vibration or heating. Drying and drying are prohibited. Safety precautions should be taken during the experiment Protect, wear goggles, gas masks, etc., in a fume hood.

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