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HJ 955-2018 English PDF

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HJ 955-2018: Ambient air－Determination of fluoride －Filter sampling / fluoride ion-selective electrode method
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HJ 955-2018319 Add to Cart 3 days Ambient air－Determination of fluoride －Filter sampling / fluoride ion-selective electrode method Valid

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Basic data

Standard ID: HJ 955-2018 (HJ955-2018)
Description (Translated English): Ambient air��Determination of fluoride ��Filter sampling / fluoride ion-selective electrode method
Sector / Industry: Environmental Protection Industry Standard
Classification of Chinese Standard: Z15
Word Count Estimation: 13,127
Date of Issue: 2018-07-29
Date of Implementation: 2018-09-01
Older Standard (superseded by this standard): HJ 480-2009
Regulation (derived from): Ministry of Ecology and Environment Announcement No. 22 of 2018
Issuing agency(ies): Ministry of Ecology and Environment

HJ 955-2018: Ambient air－Determination of fluoride －Filter sampling / fluoride ion-selective electrode method


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Ambient air-Determination of fluoride -Filter sampling/ fluoride ion-selective electrode method National Environmental Protection Standard of the People's Republic Replace HJ 480-2009 Determination of ambient air fluoride Filter sampling/fluoride ion selective electrode method Ambient air-Determination of fluoride -Filter sampling/ fluoride ion-selective electrode method Published on.2018-07-29 2018-09-01 Implementation Ministry of Ecology and Environment released i directory Foreword.ii 1 Scope 1 2 Normative references 1 3 Terms and Definitions..1 4 Principle of the method 1 5 interference and elimination..1 6 reagents and materials..2 7 instruments and equipment..3 8 samples..4 9 Analysis step 5 10 Calculation and representation of results. 5 11 Precision and Accuracy.6 12 Quality Assurance and Quality Control..6 13 Waste treatment.7 14 Notes.7 Appendix A (informative) for the determination of gaseous and particulate fluoride sampling requirements. 8

Foreword

To protect the "Environmental Protection Law of the People's Republic of China" and the "Air Pollution Control Law of the People's Republic of China" The environment, to ensure human health, to regulate the determination of fluoride in the ambient air, the development of this standard. This standard specifies the fluoride ion selective electrode method for the determination of fluoride in the ambient air. This standard is a method for sampling fluoride ion-selective electrode for the determination of fluoride in ambient air (HJ 480-2009) Revision. This standard was first published in.1995. The standard drafting unit is Baotou Environmental Monitoring Station, September 27,.2009. One revision, the revised unit is the Shenyang Environmental Monitoring Center Station. This is the second revision. The main revisions are as follows. -- Modified the sampling flow; -- Complementing the requirements for sampling head structure and sampler performance in instruments and equipment; -- Simplified standard curve preparation process; -- Increased representation of results, quality assurance and quality control, and waste disposal; -- Added informative Appendix A. From the date of implementation of this standard, "Determination of Fluoride Ion Selective Electrode Method for Determination of Fluoride in Ambient Air Fluoride" (HJ 480-2009) abolished. Appendix A of this standard is an informative annex. This standard is formulated by the Environmental Monitoring Department and the Science and Technology Standards Department. This standard was drafted. China Environmental Monitoring Station. This standard is verified by. Taiyuan Environmental Monitoring Center Station, Qinghai Environmental Monitoring Center Station, Yangzhou Environmental Monitoring Xinzhan, Zhanjiang Environmental Protection Monitoring Station, Yantai Environmental Monitoring Center Station and Inner Mongolia Autonomous Region Environmental Monitoring Center Station. This standard is approved by the Ministry of Ecology and Environment on July 29,.2018. This standard has been implemented since September 1,.2018. This standard is explained by the Ministry of Ecology and Environment. 1 Determination of ambient air fluoride filter membrane sampling/fluoride ion selective electrode method Warning. The hydrochloric acid used in the experiment is highly volatile and corrosive, and the reagent preparation process should be carried out in a fume hood; Wear protective equipment as required to avoid contact with skin and clothing.

1 Scope of application

This standard specifies the membrane sampling/fluoride ion selective electrode method for the determination of fluoride in ambient air. This standard applies to the determination of gaseous and particulate fluoride in ambient air. When the sampling flow rate is 50 L/min and the sampling time is 1 h, the detection limit of the method is 0.5 μg/m3, and the lower limit of determination is 2.0 μg/m3; When the sampling flow rate is 16.7 L/min and the sampling time is 24 h, the detection limit of the method is 0.06 μg/m3, and the lower limit of determination is 0.24 μg/m3.

2 Normative references

This standard refers to the following documents or their terms. For undated references, the valid version applies to this standard. HJ 194 Technical Specifications for Manual Air Quality Monitoring

3 Terms and definitions

The following terms and definitions apply to this standard. 3.1 Fluoride fluoride Refers to gaseous fluoride in ambient air and particulate fluoride dissolved in hydrochloric acid solution [c(HCl) = 0.25 mol/L] Fluorine meter).

4 Principle of the method

When the gaseous and particulate fluoride in the ambient air is impregnated with dipotassium hydrogen phosphate, the fluoride is fixed or retained. On the filter membrane, the fluoride on the filter membrane is immersed in a hydrochloric acid solution, and then determined by a fluoride ion selective electrode method. The fluoride ion activity in the solution is determined. The logarithm is linear with the electrode potential.

5 interference and elimination

Metal ions such as Ca2, Mg2, Fe3, and Al3 easily form complexes with fluoride ions, which negatively interfere with the results. In this Under the standard experimental conditions, the total ionic strength adjustment buffer solution was added, and the concentrations of Ca2, Mg2 and Fe3 did not exceed 50 mg/L. Al3 does not interfere with the assay when it does not exceed 2 mg/L. 26 Reagents and materials Unless otherwise stated, analytically pure reagents in accordance with national standards were used for the analysis, and experimental water was newly prepared deionized. water. 6.1 Hydrochloric acid. ρ(HCl) = 1.19 g/ml. 6.2 Sodium hydroxide (NaOH). 6.3 Sodium citrate (Na3C6H5O7·2H2O). 6.4 Sodium chloride (NaCl). 6.5 Acetic acid. w(CH3COOH) ≥ 99.5%. 6.7 Hexamethylenetetramine (C6H12N4). 6.8 Potassium nitrate (KNO3). 6.9 Titanium iron reagent (C6H4Na2O8S2·H2O). 6.10 Dipotassium hydrogen phosphate (K2HPO4·3H2O). 6.11 Sodium fluoride (NaF). excellent grade, dried at 110 ° C for 2 h, dried and cooled. 6.12 Hydrochloric acid solution. c (HCl) = 0.25 mol/L. 20.8 ml of hydrochloric acid (6.1) was dissolved in a certain amount of water and diluted to 1 L with water. 6.13 Sodium hydroxide solution. c (NaOH) = 5.0 mol/L. Weigh 100.0 g of sodium hydroxide (6.2), dissolve in water, and dilute to 500 ml after cooling. 6.14 Sodium hydroxide solution. c (NaOH) = 1.0 mol/L. Measure.200 ml of sodium hydroxide (6.13) and dilute to 1 L with water. 6.15 Dipotassium hydrogen phosphate impregnating solution. ρ(K2HPO4·3H2O)=76.0 g/L. After weighed 76.0 g of dipotassium hydrogen phosphate (6.10), it was diluted with water and diluted to 1 L. 6.16 Total ionic strength adjustment buffer solution (TISAB). 6.16.1 Total ionic strength adjustment buffer solution (TISABI). Weigh 58.0 g of sodium chloride (6.4), 10.0 g of citric acid Sodium (6.3), take 50 ml of acetic acid (6.5), add 500 ml of water to dissolve. After dissolution, add sodium hydroxide solution (6.13) 135 Ml, adjust the pH of the solution to 5.2, and dilute to 1 L with water. 6.16.2 Total ionic strength adjustment buffer solution (TISABII). Weigh 142 g of hexamethylenetetramine (6.7) and 85.0 g Potassium nitrate (6.8), 9.97 g of ferrotitanium reagent (6.9), dissolved in water, adjusted to pH 5-6, diluted with water to 1 L. 6.17 Fluorine standard stock solution. ρ (F-) = 500 μg/ml. Accurately weigh 1.1050 g of sodium fluoride (6.11), dissolve in water, and transfer to a 1000 ml volumetric flask. Concentrate with water until Mark the line and shake it. Store in a polyethylene bottle and refrigerate at 4 ° C for 6 months. You can also purchase commercially available certified standards directly. Solution. 6.18 Fluorine standard use solution. ρ (F-) = 10 μg/ml. Pipette 10.0 ml of fluoride standard stock solution (6.17) into a 500 ml volumetric flask, dilute to the mark with water, and shake well. Temporary Now equipped. 6.19 Acetic acid-nitrocellulose microporous membrane. pore size 5 μm, diameter 90 mm. 6.20 Dipotassium hydrogen phosphate impregnated filter. Use a tweezers to clamp the acetic acid-nitrocellulose microporous membrane (6.19) into the dipotassium hydrogen phosphate impregnation solution (6.15), after soaking 3 Drain (use a small amount of impregnation solution each time, with no filter membrane as the standard, after immersing 4 to 5 filter membranes, replace the new impregnation solution). Spread the impregnated filter on a polyethylene or stainless steel tray with ash-free graded filter paper and dry at 40 °C. Min ~ 1 h, until completely dry, put into a plastic box (bag), sealed and placed in a closed container for use.

7 Instruments and equipment

7.1 Atmospheric sampler. Small flow sampler with flow range from 10 L/min to 60 L/min. The sampling head can be placed at 90 mm Filter membrane, effective filter diameter is 80 mm. The sampling head is equipped with two layers of polyethylene/stainless steel support filter mesh mat, two-layer mesh mat There are 2 mm to 3 mm spacers spaced apart. The sampler is equipped with an electronic flow meter and a flow compensation system with automatic calculation The function of the volume. At a flow rate of 50 L/min, the sampling pump can overcome the pressure load of 20 kPa. Sampler appearance, work Relevant performance indicators such as environmental and temperature measurement indication error, pressure measurement indication error and flow measurement indication error should be consistent with HJ 194 regulations. The schematic diagram of the sampling head and the support mesh pad is shown in Figure 1. 1- rain cover; 2-filter membrane on the gasket; 3-filter membrane cover; 4-first filter; 5 - first support filter mesh mat (aperture 1 mm, 0.4 mm to 0.5 mm between holes); 6-spaced filter gasket; 7-second filter; 8-second support filter mesh (aperture 1 mm, 0.4 mm to 0.5 mm between holes; 9-filter under the gasket; 10-sample head base; 11-sealed O-ring Figure 1 Schematic diagram of the sampling head and support mesh pad structure 7.2 Ion activity meter or precision acidity meter. resolution is 0.1 mV. 7.3 Fluoride ion selective electrode. The range of fluoride ion concentration is measured to satisfy (10−5～10−1) mol/L. Note. Fluoride ion selective electrode and reference electrode integrated composite electrode matched with ion activity meter or acidity meter can be selected. 7.4 Reference electrode. calomel electrode/silver - silver chloride electrode. 7.5 Magnetic stirrer. stirrer with polyethylene wrap. 7.6 Ultrasonic cleaner. frequency 40 kHz to 60 kHz. 47.7 Polyethylene beaker. 100 ml. 7.8 Polyethylene bottle with lid. 50 ml, 100 ml, 1000 ml. 7.9 Common instruments and equipment used in general laboratories.

8 samples

8.1 Sample Collection 8.1.1 Ambient air sample Sample collection should be in accordance with HJ 194. Install the filter as shown in Figure 1 on the second layer of the filter mesh mat Place a di-potassium hydrogen phosphate impregnated filter with a 2 mm to 3 mm thick filter gasket in between and place the first layer A filter membrane mesh mat is placed on the first layer of the support filter mesh mat to place a second dipotassium hydrogen phosphate impregnated filter membrane. When measuring 1 h mean, collect at 50 L/min flow, at least 45 min; at 24 h mean, 16.7 L/min Flow collection, sampling at least 20 h. Note. If it is necessary to separately measure gaseous and particulate fluoride in ambient air, please refer to Appendix A for sampling. 8.1.2 Full program blank sample Take the blank filter (two) (6.20) after the same batch with the sample collection, and keep the same conditions under the same conditions. Save, transport. The blank filter is installed on the sampling head without sampling, and the blank filter is exposed at the sampling site and the sample is filtered. The film is taken out of the filter cartridge (bag) until the time it is mounted to the sampling head, then the blank filter is removed and shipped back with the sample. Laboratory. 8.2 Sample storage The filter was folded in a plastic box (bag), sealed, stored in a closed container, and analyzed in 40 days. 8.3 Preparation of samples Cut the two sample filters into small pieces (approx. 5 mm × 5 mm) and place them in a 50 ml covered polyethylene bottle (7.8). Add 20.0 ml of hydrochloric acid solution (6.12), shake well to fully disperse the membrane and soak it, then extract it in ultrasonic cleaner for 30 min. take out. Allow the solution temperature to cool to room temperature, then add sodium hydroxide solution (6.14) 5.0 ml, water 15.0 ml and TISAB dissolved Solution (6.16) 10.0 ml, total volume 50.0 ml, mix and transfer to 100 ml polyethylene beaker (7.7) to be determined. Note. The full procedure blank sample preparation is consistent with the sample filter preparation process. 8.4 Preparation of laboratory blank samples Take the same batch of immersed dipotassium hydrogen phosphate impregnated filter (two) (6.20), according to the preparation of the sample (8.3) A blank sample was prepared in the same procedure (note that the amount of water added was 14.5 ml). Adding fluorine standard to the prepared blank sample Use liquid (6.18) 0.50 ml (5.00 μg), the total volume is 50.0 ml, mix and transfer to 100 ml polyethylene beaker (7.7) It is to be determined. 59 Analysis steps 9.1 Establishment of the standard curve Pipette 0.50 ml, 1.00 ml, 2.00 ml, 5.00 ml, 10.0 ml and 20.0 ml of fluoride standard solution (6.18) In a 50 ml volumetric flask, add 10 ml of TISAB solution (6.16), dilute to the mark with water, and mix. The standard series is shown in Table 1. It can also be prepared according to the actual sample concentration, but not less than 6 points. Table 1 fluorine standard series Standard series number 1 2 3 4 5 6 Fluorine standard use liquid volume (ml) 0.50 1.00 2.00 5.00 10.0 20.0 F-content (μg) 5.00 10.0 20.0 50.0 100.200 Transfer the standard series solution to a 100 ml polyethylene cup from low to high concentration, and clean the fluoride The sub-selection electrode and the reference electrode (or composite electrode) are inserted into the test solution for measurement. Do not stir the solution before inserting the electrode to avoid Air bubbles are attached to the surface of the electrode, which affects the accuracy of the measurement. Turn on the magnetic stirrer and stir for a few minutes. The stirring speed should be moderate. stable. After the reading is stable (ie, the electrode potential changes less than 0.2 mV per minute), the stirring is stopped, and the potential response is read after standing. The value, while recording the temperature at the time of measurement. The logarithm of the fluorine content (μg) is plotted on the abscissa, and the corresponding potential value (mV) is A standard curve is established on the ordinate. Note. The temperature of the solution is controlled between 15 °C and 35 °C to ensure that the fluoride ion selective electrode works normally. 9.2 Determination of samples The measurement was carried out in the same manner as the establishment of the standard curve (9.1). The sample should be determined simultaneously with the standard curve. The temperature difference between the sample and the standard curve should not exceed ± 2 °C. 9.3 Determination of laboratory blank samples The laboratory blank sample was measured in the same manner as the measurement of the sample (9.2). Fluorine content in laboratory blank samples The difference between the measured value (μg) of the blank sample and the standard addition amount (5.00 μg), and the average value of the measurement is taken as a laboratory blank test. The fluorine content. 10 Calculation and representation of results 10.1 Calculation of results The content of fluoride in the sample is m (μg), calculated according to formula (1). (1) Where. m - the content of fluoride in the sample, μg; E - the potential value of the sample, mV; Ec - the intercept of the standard curve, mV; Sc - the slope of the standard curve, mV. 6 The content of fluoride in the ambient air sample is ρ(F-)(μg/m3), calculated according to formula (2). (2) Where. ρ(F-)——the mass concentration of fluoride in ambient air, μg/m3; m - the fluorine content of the sample measured according to 9.2, μg; M0 - the average fluorine content of the laboratory blank sample measured according to 9.3, μg; V0 - the sampling volume under the reference state (298.15 K, 101.325 kPa), m3. 10.2 Results are expressed 1 h mean value measurement, when the measurement result is less than 10.0 μg/m3, the result is retained one decimal place; when the measurement result is large At or equal to 10.0 μg/m3, the result retains three significant digits. 24 h mean value measurement, when the measurement result is less than 10.0 μg/m3, the result retains two decimal places; when the measurement result is large At or equal to 10.0 μg/m3, the result retains three significant digits. 11 Precision and accuracy 11.1 Precision Six laboratories tested the filter samples with fluoride spikes of 10.0 μg, 50.0 μg and 100 μg, respectively. The relative standard deviations in the laboratory were 1.0% to 5.4%, 0.4% to 3.1%, and 0.2% to 3.3%, respectively. Relative standard between laboratories The deviations were 1.9%, 3.1%, and 4.9%, respectively; the repeatability limits were 0.9 μg, 2.9 μg, and 5.2 μg, respectively; reproducibility limits were respectively It is 1.0 μg, 5.0 μg and 14 μg. Six laboratories collected and measured parallel samples (n=2) of ambient air in different regions, and 1 h mean The relative deviation in the laboratory was 0.8% to 18%; the mean value in the 24 h was determined to be 0% to 6.7% in the laboratory. 11.2 Accuracy Six laboratories measured the fluoride sample with a scalar volume of 10.0 μg and 100 μg, respectively, in the laboratory. The relative errors are -4.5% to 0.7% and -7.9% to 4.9%, respectively; the relative error final values are -2.3% ± 3.8% and -3.0% ± 9.4%. Six laboratories calibrated actual samples with concentrations ranging from 0.20 μg/m3 to 10.7 μg/m3 in different regions. Determination, standard addition amount 5.0 μg ~ 400 μg, 1 h mean value, the actual sample recovery rate is 80.2% ~ 98.0%, laboratory The average recovery rate of spiked standard was 91.0%, and the final value of spiked recovery was 91.0%±13.4%; the average value of 24 h was determined, the actual sample The recoveries ranged from 86.2% to 96.6%, and the average recoveries of the spiked samples were 91.4%. The final value of the spiked recovery was 91.4% ± 9.6%. 12 Quality Assurance and Quality Control 12.1 The sampler flow should be checked and calibrated before sampling, and the flow indication error should not exceed ±2%. 712.2 The flow change from the beginning to the end of sampling does not exceed ±10%. 12.3 A new standard curve should be established for each batch of sample analysis. The correlation coefficient of the standard curve is ≥0.999; the temperature is 20 °C~ When the concentration of fluoride ion changes by 10 times between 25 °C, the electrode potential change should satisfy -58.0 mV±2.0 mV. 12.4 At least two laboratory blanks should be made for each batch of samples. The blank value should be less than 1.4 μg; each batch......
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