Gas Chromatograph Detecting Indoor Environmental Pollutants

With the rapid and sound economic development of our country, the people’s living standards have been continuously improved, and many residents’ homes and units’ offices have become more and more luxurious. This has led to serious indoor environmental pollution and has led to a decline in people’s health. The number of disputes arising from the renovation has been increasing, which has aroused the attention and attention of the country. It has also taken active and effective measures to organize relevant experts to formulate national standards GB50U5-2001. In 2001, the relevant ministries jointly promulgated and stipulated the indoor Environmental air quality is an important indicator of the quality of civil construction projects, including a revision in 2006. In 2010, it was revised on the basis of the previous two revisions and released as a new national mandatory standard, namely GB503M-2010, and GB503M. - 2001 abolished. The standard stipulates that all newly-built, reconstructed and expanded civil building projects must be tested for indoor air quality when they are completed and inspected. Qualified inspections are acceptable for acceptance and delivery. In addition, more stringent requirements are imposed on building materials. Construction site use. However, due to various reasons, the management of the current market is still not perfect, and the propaganda of relevant departments at all levels is not enough, so consumers are not familiar with the pollutant indicators of various materials in the market during the purchase of houses and renovations. The blinding of unscrupulous merchants, often spending money has led to the "invisible killer", resulting in a variety of decoration disputes occur from time to time. In addition, the number of testing organizations is relatively large, and the quality of their testing services is uneven. Therefore, in light of the above situation and the situation that the author has encountered in recent years, the inspection focused on the complexity of the five indicators that must be tested in the national standards. The methods for the detection of TVOCs and the problems that should be noted in the detection process are briefly described. It is hoped that they can help the relevant personnel to communicate.

Experimental part

Experimental instruments and reagents

Instruments: gc7960 chromatograph (equipped with FID detector), Allen Analytical Instrument Co., Ltd.; thermal desorption instrument; chromatographic workstation (1pL syringe).

Standard solution: (National Standard Material Center) Standard solution concentration 1.0mg/mL (including benzene, toluene, butyl acetate, ethylbenzene, styrene, o-xylene, and undecane are all 1.0 mg/mL. Toluene 2.0 mg/mL).

Chromatographic conditions

Capillary column: 50mmx0.32mmx1^m; (2) Temperature program: column temperature: 50T/min; holding time: 10min; heating rate: 5T/min; final temperature: 250; holding time: 10min; detector temperature: 250T; Vaporization chamber temperature: 250; Sensitivity: 1010; Gas flow ratio: Air/hydrogen/nitrogen = 30:1:1; Split ratio: 5:1.

Thermal desorption conditions

Adsorbent: Tenax-TA 200 mg; desorption temperature: 300 T; desorption tube intruded into the chromatograph time: 40 s; thermal desorption time: 10 min; injection time: 40 s; desorption backflush activation time: 15 min.

Adsorption and Desorption of Standard Samples

Adsorption and Desorption of Liquid Standards: Different volumes of standard solutions were injected into a T^nax-TA tube with a 1 pL sample, and spectra for different sample volumes were obtained. Inject 0.0-L, 0.2-L, 0.4-L, 0.6-L, and 0.8^L of the standard solution into the Tenax-TA tube, and immediately place it in the desorption instrument to desorption for 10 minutes. After the time expires, the desorber automatically opens the solenoid valve. The sample was injected into the chromatogram for 40s. The desorption instrument carrier gas flow rate was 30 mL/min and the insufflation flow rate was 60 mL/min. After the air injection is completed, the solenoid valve automatically shuts off, and the time program of the chromatography station and chromatograph is turned on at the same time. The desorption instrument automatically blows at a nitrogen flow (60 mL/min) for 15 minutes to allow the aging of the rTenax-TA tube for use in the next analysis.

Thermal desorption instrument and chromatograph connection

Thermal desorption instrument with a steady flow valve, flow rate can be adjusted in 0 ~ 100mL/min. The six-way valve and solenoid valve control the thermal desorption state of the thermal desorption device and the injection tailing state. The heating system is supplied by the thermal desorption device itself. Two gas lines are available, one is always supplied with a thermal desorption instrument and chromatograph, and the other is a routed six-way valve and solenoid valve-controlled supply desorber for sample purging and tail blowing. Connect the end of the desorption tube to the solenoid valve and connect the other end directly to the inlet of the chromatograph with a connecting line. Both the thermal desorption state and the injection state can be set in the desorption instrument. The desorber automatically opens the solenoid valve to start desorption and sample injection. The degree of automation is high and the working time and labor intensity are greatly reduced.

Conclusion

With the promulgation of the national standard GB50U5-2001, government departments have been attaching great importance to the promotion of indoor environmental testing from the beginning of the promotion to the subsequent 2008 requirements that all civil construction projects must be subject to mandatory regulations for indoor environmental testing, and then to 2010 GB50325 The amendment can be seen that this standard has been widely used in practice and has been continuously improved, so that the material, etc., has been effectively controlled in terms of norms, and at the source, the material used for the improvement of people's living conditions, comfort, etc., has been ensured. The market, and then into the interior decoration, brings indoor environmental pollution. However, the level of various inspection agencies is uneven. Therefore, only by strengthening the management and supervision of testing organizations and improving their service quality and technical quality, can we effectively make our consumers Get high-quality, standardized testing services and get safety protection for the living environment.