What is the harm of benzene vapor to the human body? How is it monitored?

Exposure limits for benzene:

Chinese PC-TWA: 6 mg m3; PC-STEL: 10mg m3 ACGIH 10ppm, 32mg m3; twa: osha 1ppm， mg/m3

In other words, if you reach more than 2ppm of benzene in eight hours, it will be harmful to the human body. Pathologically, long-term exposure to benzene can cause great harm to the blood and cause chronic poisoning. Causes neurasthenic syndrome. Benzene can damage the bone marrow and make red blood cells.

White blood cells, platelets.

The number decreases and causes chromosomal aberrations, which leads to leukemia.

Aplastic anemia may even occur. Benzene can cause heavy bleeding, which suppresses the immune system.

The function of making diseases have a chance. Studies have reported that benzene can have an incubation period of up to 12-15 years in the body. Therefore, it is important to accurately monitor the trace benzene content in the surrounding environment.

The P40 portable benzene gas detector can be used by Higrid Tongjiang, the instrument applies the PID detection principle, the detection accuracy reaches 1ppb, and the automatic zero point and full-scale drift compensation can ensure the accuracy of gas concentration. The gas concentration unit can be selected, and the ppb and mg m3 are automatically switched to meet the dual needs of environmental monitoring and leakage alarm. Two-level sound and light alarm, the alarm value can be set arbitrarily.

After benzene enters the human body, phenol will be generated, which has a strong corrosive effect on mucous membranes and can damage liver function and kidney function; Inhalation of high concentrations of benzene can cause dizziness, headache, fatigue, nausea, tinnitus and other discomforts; Long-term inhalation can damage the nervous system, cause leukemia, lead to coma and even death.

Benzene can be monitored daily by installing toxic gas alarms.

First, the purpose of the experiment.

1. Master the basic operation methods and precautions of gas chromatograph.

2. Practice and master the injection method of gas chromatograph.

2. Experimental instruments.

GC4000A gas chromatograph, etc.

3. Experimental principle.

1. Chromatography is a physical or physicochemical separation and analysis method, and the main principles of its separation are: 1) based on the differences in the partition or other affinity properties of the isolated substances between the stationary phase and the mobile phase; 2) The mobile phase is caused to flow on the surface of the stationary phase, which is larger than the surface, and the substances are transferred back and forth between the two phases many times, and this difference is added up repeatedly. Small differences add up to become small, allowing the substances to be separated in a certain order.

The mobile phase used in gas chromatography is gas.

2. The FID detector is composed of an energy source and an electric field, when the components enter the flame, positive ions and negative ions are generated, which each move to the opposite electrode to form a current, which can be recorded on the instrument after amplification, which is suitable for hydrocarbons.

Fourth, experimental methods.

1) Basic operation of GC4000A gas chromatograph.

a. FID (Hydrogen Flame) Detector:

Boot 1, turn on N2, air source partial pressure, host carrier pressure, column pressure B pressure can be adjusted (adjust the peak speed or slow).

2. Turn on the power supply of the main engine, set the column, gasification, hydrogen flame and protection temperature. The protection temperature is higher than that of the column heater 30. (column temperature 100, gasification 150, hydrogen flame 150).

3. When the temperature rises, turn on the air and hydrogen. The air pressure of the air source is MPA, the air pressure of the main engine is MPA, and the flow rate A needle is cut for 8 turns (adjusted).

Close clockwise, open counterclockwise.

The hydrogen source pressure is MPa, and the main engine hydrogen pressure is MPa.

4. After turning on the air and hydrogen for 5min, put the high resistance on the low gear. Press the FID ignition switch for about 5 seconds, and after the fire is ignited, select the appropriate sensitivity and attenuation. (Mid-range, attenuation 1).

5. Turn on the computer for the workstation, and after the baseline is stable, the sample will be injected for analysis.

Shut down 1, exit the A5000 workstation, turn off the air and hydrogen, and turn the sensitivity to a low setting.

2. Press the "Total Clearing" button, open the column box door, wait for the temperature of the column box to drop to room temperature, turn off the power of the main engine, and turn off the nitrogen.

The glass pillar cannot be opened as a column door.

The FID detector is suitable for the detection of benzene series.