1、 Instrument Introduction
Benzene series compounds, also known as aromatic organic compounds (MACHs), are a general term for benzene and its derivatives. However, benzene series compounds are generally a collective term for benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene, styrene, and trimethylbenzene. Benzene series compounds are the most common compounds in the atmospheric environment and many pollutant gases. They have certain harmful effects on human health and are important pollutants in the environment. There are two methods for determining benzene derivatives in gases:
Activated carbon adsorption carbon disulfide desorption gas chromatography method: This method uses activated carbon adsorption and carbon disulfide desorption. The sensitivity of this analytical method is low, and the carbon disulfide used often contains benzene that is difficult to remove. But this method does not require special pre-processing equipment, and one sampling can be analyzed multiple times, especially when analyzing benzene derivatives with large concentration differences or high concentrations.
Thermal desorption injection gas chromatography method: This method involves the desorption of benzene derivatives from the adsorbent by heating after the sample is adsorbed by the adsorbent. Then, the benzene derivatives are carried to the chromatographic column for separation and analysis using a carrier gas. This method has high sensitivity, does not require the use of organic reagents, and has low background values. However, since the sample is injected once, multiple sampling analyses are sometimes required when the concentration of the sample cannot be determined
Shanghai Kechuang Chromatography Instrument Co., Ltd. has accumulated more than ten years of experience in specialized gas chromatographs for environmental air analysis, and continuously improves and optimizes the instruments. The adsorption tube can be directly inserted into the heating block for rapid and uniform heating, with good desorption effect.
Customers can choose between primary thermal desorption or secondary thermal desorption for sampling, or they can choose carbon disulfide desorption for sampling. One thermal desorption is achieved by directly desorbing and injecting the sample through an adsorption tube; Secondary thermal desorption refers to the adsorption of samples through adsorption tubes and secondary cold focusing, resulting in high recovery rates, good peak shapes of components, and high separation efficiency.
The HL-800 secondary thermal desorption analyzer produced by the company can be used in conjunction with various types of domestic and imported gas chromatographs or gas chromatographs, and can also be retrofitted with existing scientific and technological gas chromatographs.
2、 Detection limit
| Components | benzene | toluene | ethylbenzene | P-xylene | Meta xylene | O-xylene | Isopropylbenzene | styrene |
|
Method detection limit
mg/m3 |
5.0×10-4 | 5.0×10-4 | 5.0×10-4 | 5.0×10-4 | 5.0×10-4 | 5.0×10-4 | 5.0×10-4 | 5.0×10-4 |
|
Determination of lower limit
mg/m3 |
2.0×10-4 | 2.0×10-4 | 2.0×10-4 | 2.0×10-4 | 2.0×10-4 | 2.0×10-4 | 2.0×10-4 | 2.0×10-4 |
3、 Execution standards
| Standard Number | Standard name |
| GB/T18883-2002 | Indoor Air Quality Standards |
| GB50325-2010 | Code for Indoor Environmental Pollution Control of Civil Building Engineering (2013 Edition) |
| HJ583-2010 | Determination of Benzene Compounds in Environmental Air by Solid Adsorption/Thermal Desorption Gas Chromatography Method |
| GBZ/T 160.42-2007 | Determination of toxic substances in workplace air - Aromatic hydrocarbons |
| HJ 584-2010 | Determination of benzene derivatives in ambient air - Activated carbon adsorption/carbon disulfide desorption gas chromatography method |
| GB 11737-1989 | Hygienic inspection standard method for benzene, toluene and xylene in the atmosphere of residential areas - Gas chromatography method |
Details specified in the standard
4、 Instrument features
4.1. LCD screen or 5.7-inch color touch screen;
4.2. A fully computerized reverse control system, with a single computer capable of controlling up to 253 chromatography instruments and 7 temperature control channels; 8-channel external event time program;
4.3. The instrument is equipped with a dedicated chromatography workstation for ambient air, which has functions such as intelligent peak identification/automatic processing, multi-channel spectrum integration and exchange, automatic conversion of sampling volume to standard state based on ambient temperature and pressure, and automatic calculation of the content of each component and the whole in the unit sampling volume. It can also deduct the peak area of each component in the solvent and the content of each component in the outdoor air sample to obtain the final result;
4.4. The instrument adopts RJ45 Ethernet interface, which makes signal output and control acquisition simple and convenient, and can realize remote control, remote data transmission, processing and supervision of the instrument. Can be connected to unit supervisors and higher-level supervisors for easy supervision by supervisors;
4.5. Large capacity column box with automatic rear opening door, capable of 8-step programmed heating, and column box with near room temperature control function (5 ℃ above room temperature);
4.6. Equipped with fault self diagnosis function, displaying the location and nature of the fault at any time; Equipped with over temperature protection function, any temperature exceeding the set temperature will automatically stop heating.
Note: For other parameters of the instrument, please refer to the introduction of the gas chromatography host.
GC9800 gas chromatograph (link)
GC2002 gas chromatograph (link)
5、 Instrument configuration
Configuration of a thermal analysis instrument
| Product Name | Specifications | quantity |
| GC9800 type
(Networked) |
1. GC9800 networked chromatography host;
2. Hydrogen flame ionization detector (FID); 3. Fill column sampler+capillary column injection system; 4. A thermal analysis device injection system; 5. Benzene series analysis dedicated chromatographic column; 6. Two heating systems for the injection valve and output pipeline; 7. Calibration system. 8. Built in HL-3000 chromatography workstation for environmental air analysis 9. Spare parts package (including purification tubes, instrument tool accessories, etc.) |
1 unit |
| Adsorption tube | U-shaped stainless steel, 0.2g Tenax adsorbent | 10 pieces |
| Other options available | ||
| KCA-3000 model
Air generator |
Flow rate: 3L/min, imported oil-free compressor | 1 unit |
| KCH-300 type
Hydrogen generator |
Purity:>99.999%, Flow rate: 300ml/min | 1 unit |
| carrier gas | High purity nitrogen, purity>99.999%, with pressure reducing valve | 1 bottle |
| computer | Lenovo, XP or Win7 32-bit system | 1 unit |
| DHX type adsorption tube activation box | Can activate 8 tubes simultaneously, with standard sample activation calibration system | 1 unit |
| Benzene based standard samples (5 pieces/set) | Benzene derivatives (for thermal desorption method) 8 components (methanol as solvent) | 1 set |
| air sampler | air sampler | |
Secondary thermal analysis instrument configuration
| Product Name | Specifications | quantity |
| GC9800 type
(Networked) |
1. GC9800 networked chromatography host;
2. Hydrogen flame ionization detector (FID); 3. Fill column sampler+capillary column injection system; 4. HL-800 type secondary thermal analysis device injection system; 5. Benzene series analysis dedicated chromatographic column; 6. Output pipeline heating system; 7. Calibration system. 8. Built in HL-3000 chromatography workstation for environmental air analysis 9. Spare parts package (including purification tubes, instrument tool accessories, etc.) |
1 unit |
| Adsorption tube | U-shaped stainless steel, 0.2g Tenax adsorbent | 10 pieces |
| Other options available | ||
| KCA-3000 model
Air generator |
Flow rate: 3L/min, imported oil-free compressor | 1 unit |
| KCH-300 type
Hydrogen generator |
Purity:>99.999%, Flow rate: 300ml/min | 1 unit |
| carrier gas | High purity nitrogen, purity>99.999%, with pressure reducing valve | 1 bottle |
| computer | Lenovo, XP or Win7 32-bit system | 1 unit |
| DHX type adsorption tube activation box | Can activate 8 tubes simultaneously, with standard sample activation calibration system | 1 unit |
| Benzene based standard samples (5 pieces/set) | Benzene derivatives (for thermal desorption method) 8 components (methanol as solvent) | 1 set |
| air sampler | air sampler | 1 unit |
Instrument detailed parameter link: The gas chromatography host can be selected from GC9800 or GC2002 models
GC9800 gas chromatograph
GC2002 gas chromatograph
6、 Workstation operation interface
7、 Analyze the graph
Analysis spectrum of benzene standard sample 3 # (0.5mg/ml)
Analysis spectrum of benzene series (five components) standard sample
Analysis spectrum of benzene series (eight components) standard sample
Guiding technical article link
[1] Zhang Tianlong, Shi Jin, Qi Xiaohua Experimental study on the application of secondary thermal desorption technology to analyze TVOC [C]. Cross Strait Conference on Analytical Chemistry two thousand and six
[2] Zhang Tianlong, Qi Xiaohua, Shi Jin Rapid and accurate analysis of benzene derivatives in air using activated carbon tube secondary thermal desorption direct injection method [C]. Chemshow. cn. 2006
[3] State Environmental Protection Administration Monitoring and Analysis Methods for Air and Waste Gas [M]. China Environmental Science Press, two thousand and three
[4] Xu Bohong, Yan Huifang Monitoring Methods for Hazardous Substances in the Workplace [M]. China People's Public Security University Press, two thousand and three
[5] Cui Jiusi Indoor Air Pollution Monitoring Method [M]. Chemical Industry Press, two thousand and two
[6] Cui Jiusi Indoor Environment Detection Instruments and Application Technology [M]. Chemical Industry Press, two thousand and four
National/Industry Standard Links
GB/T18883-2002 Indoor Air Quality Standards
GB50325-2010 Code for Indoor Environmental Pollution Control of Civil Building Engineering (2013 Edition)
HJ583-2010 Determination of Benzene Compounds in Environmental Air Solid Adsorption/Thermal Desorption Gas Chromatography Method
GBZ/T 160.42-2007 Determination of Toxic Substances in Workplace Air - Aromatic Hydrocarbons
HJ 584-2010 Determination of Benzene Compounds in Environmental Air Activated Carbon Adsorption/Carbon Disulfide Desorption Gas Chromatography Method
GB 11737-1989 Standard Method for Hygienic Inspection of Benzene, Toluene, and Xylene in the Atmosphere of Residential Areas - Gas Chromatography Method
