VOCS adsorption tube (combination sampling tube)

This sampling tube is suitable for fixed pollution source exhaust gasDetermination of 24 volatile organic compounds, including acetone, isopropanol, n-hexane, ethyl acetate, benzene, hexamethyldisiloxane, 3-pentanone, n-heptane, toluene, cyclopentanone, ethyl lactate, butyl acetate, propylene glycol monoether acetate, ethylbenzene, p-xylene, 2-heptanone, styrene, o-xylene, benzyl ether, benzaldehyde, 1-decene, 2-nonanone, and 1-dodecene.

Refer to the national standard

HJ 734-2014 Determination of volatile organic compounds in fixed source exhaust gas Solid phase adsorption thermal desorption/gas chromatography-mass spectrometry method

Adsorption tube: made of stainless steel material, inner diameter5mm。

combination1 adsorption tube, internal installationTenax GR、Carbopack B， The lengths are 30mm and 25mm respectively.

combination2 adsorption tubes, containing Carbopack B and Carboxen 1000, with lengths of 30mm and 10mm respectively.

combination3 adsorption tubes, containing Carbopack C, Carbopack B, and Carboxen 1000, with lengths of 13mm, 25mm, and 13mm respectively. Or use other products with the same functionality.

HJ 644-2013 Determination of volatile organic compounds in ambient air - Adsorption tube sampling - Thermal desorption/gas chromatography-mass spectrometry method

Adsorption tube: made of stainless steel or glass material, inner diameter6mm， Fill with Carbopack C, Carbopack B, and Carboxen 1000, with lengths of 13mm, 25mm, and 13mm respectively. Or use other products with the same functionality.

The use and selection of adsorption tubes

C. 1. General requirements for adsorption sampling tubes

Commercialized adsorption sampling tubes can be purchased or self filled. The adsorption sampling tube should be labeled with a number and airflow direction. The distance between the end face of the solid adsorbent loaded and the inlet of the sampling tube should be at least15mm， The adsorption bed should be completely within the thermal desorption zone. One adsorbent can be selected as needed, or two or three adsorbents can be selected. When selecting two or more adsorbents, glass wool without silanization should be used to separate them. When selecting three adsorbents, they should be filled in order of their adsorption strength. Typically, weak adsorbents have a specific surface area of less than 50m²/g， Medium strength adsorbents have a specific surface area of 100-500m²/Within the range of g, the specific surface area of the strong adsorbent is 1000m²/About g. The particle size of commonly used adsorbents is generally 60-80 mesh, and the filling amount is 200mg. For multi-layer adsorbents (the total filling amount is generally around 450mg).

C. 2 Common combinations of adsorbents and their applicable scope

C. 2.1 Combination 1 adsorption sampling tube

apply toCompounds within the range of C6-C20 can have a sampling volume of up to 2L at any ambient temperature, and for compounds above C7, the sampling volume can be expanded to 5L. The aging temperature is 330 ℃ and the aging flow rate is 100mL/min. Domestic combination adsorption sampling tube with the same function: equipped with GDX502 and GDX101 or GDX201, filling lengths of 30mm and 20mm respectively, thermal desorption temperature of 220 ℃, aging temperature of 240 ℃, can be selected for self filling.

C. 2.2 Combination 2 adsorption sampling tube

apply toCompounds within the range of C3 to C12. When the humidity is below 65% and the temperature is below 30 ℃ (with a moisture content of 1.8%), the sampling volume should be reduced to 0.5L; for compounds above C4, the sampling volume can be increased to 5L. The aging temperature is 350 ℃ and the aging flow rate is 100mL/min.

C. 2.3 Combination 3 Adsorption Sampling Tube

Compounds within the range of C3 to C16. When the humidity is below 65% and the temperature is below 30 ℃ (with a moisture content of 1.8%), the sampling volume should be reduced to 0.5L; for compounds above C4, the sampling volume can be increased to 5L. The aging temperature is 350 ℃ and the aging flow rate is 100mL/min.

C. 3 combinations of 1 adsorption sampling tube for safe sampling volume of some low boiling point volatile organic compounds

outsideC. The safe sampling volume (mL) of some low boiling point volatile organic compounds using a combination 1 adsorption sampling tube.

outsideC. 1 Combination 1 Adsorption Sampling Tube for Safe Sampling Volume of Some Low Boiling Volatile Organic Compounds (mL)

C. Selection of 4 adsorption sampling tubes

Volatile organic compounds in fixed source exhaust（The three recommended combination adsorption sampling tubes should be used for VOCs sampling. Combination 1 adsorption sampling tube is not suitable for sampling butane, pentane, dichloromethane, methanol, ethanol, acetone, and acetonitrile at 40 ℃; Combination 2 adsorption sampling tube is not suitable for sampling dodecane, nitrobenzene, and phenol; Combination 3 adsorption sampling tube is not suitable for sampling phenol. For volatile organic compounds with known components, other suitable adsorption tubes can also be used for sampling. During pre monitoring, a combination of 3 adsorption sampling tubes can be used for sampling, and the compound can be qualitatively analyzed using mass spectrometry full scan method. During formal monitoring, a combination of 1 adsorption sampling tube is used for sampling and qualitative and quantitative analysis, and it is determined that low boiling point organic matter meets the sampling conditions for a minimum gas production of 300mL.