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HJ 759-2023 English PDF

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HJ 759-2023: Ambient air - Determination of 65 volatile organic compounds - Collected in canisters and analyzed by gas chromatography/mass spectrometry
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HJ 759-2023English1709 Add to Cart 9 days [Need to translate] Ambient air - Determination of 65 volatile organic compounds - Collected in canisters and analyzed by gas chromatography/mass spectrometry Valid HJ 759-2023
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Basic data

Standard ID HJ 759-2023 (HJ759-2023)
Description (Translated English) Ambient air - Determination of 65 volatile organic compounds - Collected in canisters and analyzed by gas chromatography/mass spectrometry
Sector / Industry Environmental Protection Industry Standard
Classification of Chinese Standard Z15
Word Count Estimation 77,718
Date of Issue 2023-02-09
Date of Implementation 2023-08-01
Issuing agency(ies) Ministry of Ecology and Environment
Summary This standard specifies the tank sampling/gas chromatography-mass spectrometry method for the determination of 65 volatile organic compounds in ambient air and fugitive emission monitoring points. This standard applies to the determination of 65 kinds of volatile organic compounds in ambient air and fugitive emission monitoring points.

HJ 759-2015: Ambient air. Determination of volatile organic compounds. Collected by specially-prepared canistersand analyzed by gas chromatography/mass spectrometry


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Ambient air.Determination of volatile organic compounds.Collected by specially-prepared canistersand analyzed by gas chromatography/mass spectrometry People's Republic of China National Environmental Protection Standard Measurement of Ambient Air Volatile Organic Compounds Canister sampling/gas chromatography-mass spectrometry Ambient air-Determination of volatile organic compounds- Collected by Specially-prepared canistersand analyzed by gas chromatography/mass spectrometry Published October 22,.2015 2015-12-01 Implementation release Ministry of Environmental Protection i directory Preface.ii 1 Scope of application.1 2 Normative references 1. 3 Methodology.1 4 Reagents and Materials 1 5 Instruments and Equipment 2 6 Sample 2 7 Analysis Steps.4 8 Calculation and Expression of Results.6 9 Precision and Accuracy.7 10 Quality Assurance and Quality Control..7 11 Precautions .8 Appendix A (Normative) Method Detection Limits and Determination Limits.9 Appendix B (Informative) Method Precision and Accuracy.11 Appendix C (Informative Appendix) Correspondence between Internal Standards and Target Compounds. 27 Appendix D (Informative Appendix) Total Ion Current VOCs .29

Foreword

To protect the environment 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 Prevention and Control of Atmospheric Pollution To ensure human health and regulate the monitoring methods for volatile organic compounds in the ambient air, this standard is formulated. This standard specifies canister sampling/gas chromatography-mass spectrometry methods for the determination of volatile organics in the ambient air. This standard is the first release. Appendix A of this standard is a normative appendix, and Appendix B to Appendix D are informative appendices. This standard is formulated by the Department of Science and Technology Standards of the Ministry of Environmental Protection. This standard is mainly drafted by. Jiangsu Provincial Environmental Monitoring Center. This standard verification unit. Suzhou City Environmental Monitoring Center Station, Changzhou Environmental Monitoring Center Station, Taizhou City Environmental Monitoring Xinzhan, Wuxi Environmental Monitoring Center Station, Zhenjiang Environmental Monitoring Center Station, and Hulunbeier Environmental Monitoring Station. This standard was approved by the Ministry of Environmental Protection on October 22,.2015. This standard will be implemented as of December 1,.2015. This standard is explained by the Ministry of Environmental Protection.

1 Determination of Ambient Air Volatile Organic Compounds

Canister sampling/gas chromatography-mass spectrometry Warning. The standards used in the experiment are volatile toxic chemicals. They should be used under the ventilation conditions. The operation should be in accordance with regulations. Wear protective equipment and avoid inhalation or contact with skin and clothing.

1 Scope of application

This standard specifies canister sampling/gas chromatography-mass spectrometry for the determination of volatile organics in the ambient air. This standard applies to the determination of 67 volatile organic compounds such as propylene in the ambient air. Other volatile organic compounds The applicability verification of the method can also be determined by this standard. When the sample size is 400 ml, the detection limit of this method is 0.2 μg/m3~2 μg/m3 in full scan mode. The limit is 0.8 μg/m3~8.0 μg/m3. See Appendix A for details.

2 Normative references

The content of this standard refers to the following documents or the terms therein. For undated references, the valid version is suitable Used for this standard. HJ/T 194 Manual Monitoring of Ambient Air Quality Specifications

3 Methodology

The ambient air sample is collected in a stainless steel tank that has been inerted by the inner wall. After concentration by a cold trap and thermal analysis, it enters the gas phase. Spectral separation, detection using a mass spectrometer detector. Qualitative and internal standard method quantification by comparison with the mass spectrogram and retention time of the reference material.

4 Reagents and materials

4.1 Standard gas. The concentration is 1 μmol/mol. High-pressure cylinders are kept, the cylinder pressure is not lower than 1.0 MPa, and can be stored for 1 year (or See the relevant specification of the gas certificate). According to the actual work needs, purchase certified gas or customized in qualified units Suitable mixing standard gas. 4.2 Standard gas use. Using a gas dilution device (5.6), dilute standard gas (4.1) with high purity nitrogen (4.8) to 10 nmol/mol concentration, can be stored for 20 days. 4.3 Internal standard gas (certified reference material). The components are. monobromochloromethane, 1,2-difluorobenzene, and chlorobenzene-d5. Concentration is 1 μmol/mol. High pressure cylinders are kept and the cylinder pressure is not less than 1.0 MPa. Can be stored for 1 year (or see phase of certificate gas certificate) Off instructions). This standard recommends the use of the above-mentioned 1 to 3 kinds of internal standard substances, and other substances may also be used as internal standard substances. 24.4 Internal standard gas use. use gas dilution device (5.6), internal standard gas (4.3), high purity nitrogen (4.8) Diluted to 100 nmol/mol concentration for 20 days. 4.5 4-Bromofluorobenzene standard gas. 1 μmol/mol, mixed with internal standard gas (4.3), high pressure cylinder Storage, cylinder pressure not less than 1.0 MPa, can be stored for 1 year (or see the relevant specification of the gas certificate). 4.6 4-Bromofluorobenzene Standard Gases. Using a gas dilution device (5.6), 4-bromofluorobenzene standard gas (4.5), with high Pure nitrogen (4.8) was diluted to 100 nmol/mol for 20 days. 4.7 Helium. ≥99.999%. 4.8 High-purity nitrogen. ≥99.999%, with hydrocarbon removal device. 4.9 High-purity air. ≥ 99.999%, with hydrocarbon removal device. 4.10 liquid nitrogen.

5 Instruments and Equipment

5.1 Gas Chromatograph-Mass Spectrometer. The gas phase part has an electronic flow controller, and the column oven has a program temperature increase function. Equipped with column oven cooling device. The mass spectrometer section has a 70 eV electron impact (EI) ion source with full scan/select ion (SIM) Scan, automatic/manual tuning, library search, and more. 5.2 Capillary Columns, 60 m × 0.25 mm, 1.4 μm Thickness (6% N-Butylphenyl-94% Dimethyl Polysiloxane) Fixative), or other equivalent capillary column. 5.3 Gas trap concentrator. It has the function of automatic quantitative sampling and automatic addition of standard gas and internal standard. At least two Grade cold trap. The first stage cold trap can be cooled to -180 °C, and the second stage cold trap can be cooled to -50 °C; The third stage of the function of the cold trap (can be cooled to -180 °C), the better. Gas Condenser and Gas Chromatography-Mass Spectrometer The connecting pipes are made of inert materials and can be heated in the range of 50 °C to 150 °C. 5.4 Concentrator Autosampler. Sample sampling sample can be automatically injected. 5.5 Tank Cleaning Device. The sampling tank can be pumped to vacuum (< 10 Pa) with heating, humidifying, and pressure cleaning functions. 5.6 Gas Dilution Unit. The maximum dilution can be up to 1000 times. 5.7 Sampling tanks. stainless steel sampling tanks with inert walls, with capacities of 3.2 L and 6 L. Withstand pressure value >241 kPa. 5.8 liquid nitrogen tank. stainless steel, volume is 100 L ~200 L. 5.9 Flow Controller. It is used with the sampling tank and calibrated with a standard flow meter before use. 5.10 Calibrate the flowmeter. accurately measure the flow rate in the range of 0.5 ml/min to 10.0 ml/min or 10 ml/min to 500 ml/min. 5.11 vacuum pressure gauge. accuracy requirements ≤ 7 kPa (1 psi), pressure range. -101 kPa ~ 202 kPa. 5.12 Filter. Aperture ≤ 10 μm.

6 samples

6.1 Preparation before sampling Tank cleaning. Use the tank cleaning device (5.5) to clean the sampling tank. The cleaning process can be performed according to the tank cleaning device instructions. Do the operation. The sampling tank can be humidified during the cleaning process to reduce the active adsorption of the tank. If necessary, the sampling tank can be 50 °C ~ 80 °C heating cleaning. 3 After the cleaning is completed, the sampling tank is evacuated (< 10 Pa) and used. For each 20 sampling tanks cleaned, at least one tank should be used to inject high-purity nitrogen gas analysis to determine if the cleaning process is clean. Each After the vacuum tank of the high concentration sample is cleaned, the background pollution should be analyzed before the next use. 6.2 Sample Collection Sample acquisition can be instantaneous sampling and constant flow sampling in two ways. Sampling requires a filter (5.12) to go In addition to airborne particles. Instantaneous sampling. Take the sample tank (5.7) that has been cleaned and evacuated to the sampling point and install the filter (5.12). Open the sampling tank valve and begin sampling. After the pressure in the tank is the same as the atmospheric pressure at the sampling point, close the valve and seal it with a cap. seal. Record the sampling time, location, temperature, humidity, and atmospheric pressure. See HJ/T 194 for details. Constant flow sampling. Take the cleaned and evacuated sampling tank (5.7) to the sampling point, install the flow controller (5.9) After the filter (5.12), open the sampling tank valve and start the constant current sampling, at the sampling corresponding to the set constant flow rate After the gap is reached, close the valve and seal with a sealing cap. Record sampling time, location, temperature, humidity, atmospheric pressure, specific parameters See HJ/T 194. Sample tanks (5.7) with a volume of 3.2 L and 6 L are shown in Table 1 for sampling times corresponding to different constant flow rates. Table 1 Sample times corresponding to different constant flow rates 3.2 L 6 L Sampling flow (ml/min) corresponds to the sampling time sampling flow (ml/min) corresponding sampling time 48 ml/min 1 hour 90 ml/min 1 hour 6.2 ml/min 8 hours 12 ml/min 8 hours 2.1 ml/min 24 hours 3.8 ml/min 24 hours 6.3 Sample preservation Samples were stored at room temperature and analyzed as soon as possible after sampling. Analysis was completed within 20 days. 6.4 Sample Preparation Before the actual sample analysis, the pressure in the tank shall be determined using a vacuum pressure gauge (5.11). If the tank pressure is less than 83 kPa, it must be Use high purity nitrogen to pressurize to 101 kPa, and calculate the dilution factor according to equation (1). Yf  (1) Where. f - dilution factor, dimensionless; aX - tank pressure before dilution, kPa; aY - Tank pressure after dilution, kPa. 6.5 Blank preparation 6.5.1 Lab Blank Connect the sample tank (5.7) pre-cleaned and pumped to vacuum to the gas dilution unit (5.6) to open the high-purity nitrogen gas (4.8) or high purity air (4.9) valves. After the sample tank pressure reaches the preset value (typically 101 kPa), close the sample Tank valves and cylinder valves. 6.5.2 Transport Blank 4Inject high-purity nitrogen (4.8) or high-purity air (4.9) into a pre-cleaned and pumped to sample tank (5.7) Take it to the sampling site and send it back to the laboratory for analysis with the sample tank (5.7) after the same batch of sample was taken.

7 Analysis steps

7.1 Instrument Reference Conditions 7.1.1 Reference Conditions for the Cold Trap Concentrator Sample volume 400 ml (according to the target compound concentration in the sample, the sampling volume can be adjusted in the range of 50 ml to 1000 ml whole). Primary cold trap. trapping temperature. -150 °C; trapping flow. 100 ml/min; analytical temperature. 10 °C; valve temperature. 100 °C; baking temperature. 150 °C; baking time. 15 min. Secondary cold trap. trapping temperature. -15°C; trapping flow rate. 10 ml/min; trapping time. 5 min; analytical temperature. 180 °C; Resolution time. 3.5 min; Baking temperature. 190 °C; Baking time. 15 min. Three-level focusing. Focusing temperature. -160 °C; Resolution time. 2.5 min; Baking temperature..200 °C; Baking time. 5 min. Transmission line temperature. 120 °C. 7.1.2 Gas chromatographic reference analysis conditions. Program temperature rise. initial temperature 35 °C, hold for 5 min, heat up to 150 °C at 5 °C/min, keep 7 min Afterwards, the temperature was raised to.200 °C at a rate of 10 °C/min for 4 min. Inlet temperature. 140 °C. Solvent delay time. 5.6 min. Carrier gas flow rate. 1.0 ml/min. 7.1.3 Mass Spectrometry Reference Analysis Conditions Interface temperature. 250 C. Ion source temperature. 230 C. Scan mode. EI (full scan) or selective ion scan (SIM). Scan range. 35 amu to 300 amu. Note. The best working conditions for different types of instruments should be different according to the instrument instructions. This standard gives the instrument reference condition. 7.2 Instrument Performance Check Before analyzing the sample, check the GC/MS instrument performance. 4-bromofluorobenzene standard use gas (4.6) via the atmosphere Concentrator injection 50.0 ml. The resulting abundance of BFB key ions must meet the criteria in Table 2. Table 2 Key Abundance Standards for 4-Bromofluorobenzene Mass ion abundance standard mass ion abundance standard 50 to 90% of quality 95 of 8% to 40% of 174 quality of 95 75 to 95 percent of quality 95 4% to 9% of 175 quality 174 95 base peaks, 100% relative abundance 176 masses 93% to 101% of 174 596 Quality 5% to 9% 177 Quality 176 5% to 9% 173 less than 2% of the quality 174 7.3 Calibration 7.3.1 Standard Gas Preparation The standard gas concentration is 10 nmol/mol. the standard gas (4.1) cylinder and the high purity nitrogen (4.8) cylinder are Connect the gas dilution device (5.6), set the dilution factor, open the cylinder valve and adjust the flow rate of the two gases until the flow rate is stable. Connect the sampling tank (5.7) pre-cleaned and vacuumed to the gas dilution unit (5.6) and open the sampling tank valve. The door began to be formulated. After the tank pressure reaches the preset value (typically 172 kPa), close the sample tank valve and the cylinder gas valve. 7.3.2 Internal standard gas preparation The internal standard uses a gas concentration of 100 nmol/mol. The internal standard gas (4.3) is prepared according to the procedure in 7.3.1. 7.3.3 Draw a calibration curve Extract 50.0 ml, 100 ml,.200 ml, 400 ml, 600 ml, 800 ml standard use gas (4.2), After adding 50.0 ml of internal standard gas (4.4), the target concentrations were 1.25 nmol/mol and 2.5 nmol/mol, respectively. 5.0 nmol/mol, 10.0 nmol/mol, 15.0 nmol/mol, 20.0 nmol/mol (adjustable according to the actual sample) In the standard series, the internal standard concentration is 12.5 nmol/mol. According to the instrument reference conditions, proceed from low to high concentrations in order Determination. Calculate the relative response factor (RRF) of the target according to formula (2), and calculate the target's full scale according to formula (3) The average relative response factor (RRF) at the quasi-concentration point. Is Is RRF   (2) Where. RRF - the relative response factor of the target, dimensionless; Ax - target compound quantitative ion peak area; Ais - internal standard compound quantitative ion peak area;  is - mole fraction of the internal standard compound, nmol/mol; x - mole fraction of the target compound, nmol/mol. Ii  RRFRRF (3) Where. RRF - average relative response factor of the target, dimensionless; RRFi - the relative response factor of the i-th object in the standard series, dimensionless; n - standard series of points. 7.3.4 Total Ion Current Map (TIC) The total ion chromatogram of the target compound is shown in Appendix D. 7.4 Sample Determination The prepared sample (6.4) is connected to a gas trap condenser (5.3), and 400 ml of the sample is concentrated and analyzed. Add 50.0 ml of standard internal standard gas (4.4) and determine according to the instrument reference conditions (7.1). 7.5 blank sample determination The same procedure as for the sample measurement was used to determine the laboratory blank (6.5.1) and the shipping blank (6.5.2). 68 Calculation and Representation of Results 8.1 Qualitative Analysis Determination of the relative retention time of the target in the sample, auxiliary qualifier ions, and quantitative ions in a full scan The abundance ratio is qualitatively compared with the target in the standard. The relative retention time of the target compound in the sample and the calibration series The relative retention time of the compounds should be within ±3.0%. Auxiliary Qualitative Ions and Quantitative Isolation of Target Compounds in Samples Sub-Area Area Ratio (Q-Samples) vs. Standard Series Target Compounds Auxiliary Qualitative Ions and Quantitative Ion Peak Area Ratio (Q-Standard) The relative deviation is controlled within ±30%. Calculate relative retention time RRT according to equation (4) isRT RTRRT c (4) Where. RRT - Relative retention time of the target compound, dimensionless; RTc -- Retention time of the target compound, min; RTis - Retention time of the internal standard, min. Calculate the average relative retention time (RRT) according to equation (5). the relative protection of the same target compound in the standard series Average time remaining. Ii RRTRRT (5) Where. RRT - average relative retention time of the target, dimensionless; iRRT - the relative retention time of the i-th object in the standard series, dimensionless; n - standard series of points. Calculate the area ratio of auxiliary qualifier ions and quantitative ions according to formula (6) Q  (6) In the formula. Q - Auxiliary qualitative ion and quantitative ion peak area ratio; At -- quantitative ion peak area; Aq - Auxiliary qualitative ion peak area. 8.2 Quantitative analysis Using the average relative response factor for quantitative calculations, the target's quantification ions, as well as each target and internal standard Refer to Appendix C for the correspondence. The content of the target in the sample (μg/m3) was calculated according to formula (7). fM RRFA A is Is x  4.22  (7) In the formula.  - the concentration of the target in the sample, μg/m3; xA - Quantitative ion peak area of the target in the sample; isA - quantitative ion peak area of the internal standard in the sample; 7is - mole fraction of the internal standard in the sample, nmol/mol; RRF - average relative response factor of the target, dimensionless; f - dilution factor, dimensionless; M - the molar mass of the target, g/mol, see Appendix C; 22.4 - Molar volume of gas in the state (273.15 K, 101.325 kPa), L/mol. 8.3 Result representation When the measurement result is less than 100 μg/m3, retain one decimal place; when the measurement result is greater than or equal to 100 μg/m3 , keep 3 significant figures.

9 Precision and Accuracy

9.1 Precision Six labs had four concentrations of 0.5 nmol/mol, 2.5 nmol/mol, 5.0 nmol/mol, and 20.0 nmol/mol The uniform sample was subjected to six replicate measurements. The relative standard deviations in the laboratory were. 1.2% to 13.1%, 0.6% to 9.6%, respectively. 0.6% to 8.6%, 0.5% to 7.7%; inter-laboratory relative standard deviations were. 2.4% to 14.0%, 4.0% to 12.9%, respectively. 1.7% to 8.9%, 1.3% to 9.7%; repeatability limits were 0.13 μg/m3 to 0.90 μg/m3 and 0.71 μg/m3 to 3.29 μg/m3, respectively. 0.52 μg/m3 to 3.31 μg/m3 and 1.60 μg/m3 to 18.1 μg/m3; reproducibility limits were 0.26 μg/m3 to 1.49 μg/m3, respectively. 1.32 μg/m3 to 6.18 μg/m3, 0.95 μg/m3 to 9.28 μg/m3, 6.03 μg/m3 to 24.2 μg/m3. See Appendix B for details. 9.2 Accuracy Six laboratories weighed 2.5 nmol/mol, 5.0 nmol/mol, and 20.0 nmol/mol ambient air samples respectively. The recovery rate of the spiked standard was measured six times. The recoveries for the spiked standard were. 76.1% to 105%, 81.7% to 110%, and 80.6% to 109%. See Appendix B for details. 10 Quality Assurance and Quality Control 10.1 blank The concentration of the target in transport blanks and laboratory blanks should be lower than the lower limit of the method determination. Otherwise, you should find out why Take appropriate measures to eliminate interference or pollution. 10.1.1 Lab Blank High-purity nitrogen is injected into the clean sampling tank as a laboratory blank, and laboratory blank testing must be performed before analysis of each batch of samples. test. 10.1.2 Transport Blank Each batch of samples analyzes at least one transport blank. First inject high purity nitrogen (4.8) or high purity air (4.9) into vacuum Clean the sampling tank and bring it to the sampling site. After the same process as the sample (including on-site exposure, transportation, storage With laboratory analysis) and steps. 10.2 Determination of Parallel Samples One parallel sample was analyzed every 10 samples or batches (less than 10 samples/lot). Relative to the target in parallel samples The deviation should be less than or equal to 30%. Otherwise, find the cause and reanalyze it. 810.3 Internal Standards The retention time of the internal standard in the sample is deviated from the retention time of the internal standard in the calibration curve that was continuously calibrated or most recently plotted on that day. Should not exceed 20 s, quantitative ion peak area change should be between 60% to 140%. 10.4 Calibration Curve The calibration curve needs at least 5 concentration points, and the relative standard deviation (RSD) of the relative response factor of the target should be less than At 30%, otherwise look for the cause and redraw the standard curve. 10.5 Continuous Calibration Analyze the middle or next highest point of the calibration curve every 24 h. The relative deviation between the measurement result and the initial concentration value Should be less than or equal to 30%, otherwise look for the cause or redraw the standard curve. 11 Precautions 11.1 The experimental environment should be kept away from organic solvents and reduce or eliminate the background noise of organic solvents and other volatile organic compounds. 11.2 Volatile organic compounds volatilized from the gas circuit connecting materials in the sample introduction system and the cold trap concentration system will interfere with the analysis. Properly increase and lengthen baking time to minimize interference. 11.3 Pipelines and joints through which all samples pass must be inerted and insulated to eliminate sample adsorption, condensation and Fork pollution. 11.4 Volatile organics (especially dichloromethane and fluorocarbons) may pass through valves, etc. during transport preservation The parts diffuse into the sampling tank and contaminate the sample. After the sample collection is completed, the valve must be fully closed and sealed with a sealing cap Sampling tank sampling port, isolated from outside air, can effectively reduce such interference. 11.5 After analysis of high-concentration samples, blank analysis must be added. If any residue is found in the analysis system, the gas cold trap can be used to condense. The baking process of the apparatus removes residues.

9 Appendix A

(Normative Appendix) Method detection limit and lower limit of measurement When the sampling amount is 400 ml, the detection limit and the lower limit of detection in the full scan mode are shown in Table A. Table A Method Detection Limits and Determination Limits Target Compound Detection Limit (μg/m3) Lower Determination Limit (μg/m3) 1 Propylene 0.2 0.8 2 Difluoromethane dichloromethane 0.5 2.0 3 1,1,2,2-Tetrafluoro-1,2-dichloroethane 0.6 2.4 4 Methyl chloride 0.3 1.2 5 Vinyl chloride 0.3 1.2 6 Butadiene 0.3 1.2 7 Methanethiol 0.3 1.2 8 Monobromomethane 0.5 2.0 9 Chloroethane 0.9 3.6 10 Fluorotrichloromethane 0.7 2.8 11 Acrolein 0.5 2.0 12 1,2,2-trifluoro-1,1,2-trichloroethane 0.7 2.8 13 1,1-Dichloroethylene 0.5 2.0 14 Acetone 0.7 2.8 15 Methyl sulfide 0.5 2.0 16 Isopropyl alcohol 0.6 2.4 Carbon disulfide 0.4 1.2 18 Dichloromethane 0.5 2.0 19 cis-1,2-dichloroethylene 0.5 2.0 20 2-methoxy-methylpropane 0.5 2.0 21 hexane 0.3 1.2 22 Ethylene dichloride (1,1-dichloroethane) 0.7 2.8 23 Vinyl Acetate 0.5 2.0 24 2-Butanone 0.5 2.0 25 Reverse 1,2-Dichloroethylene 0.8 3.2 26 Ethyl acetate 0.6 2.4 27 Tetrahydrofuran 0.7 2.8 28 chloroform 0...

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