Aiming at features of organic volatile gas is less in the air and not easily be detected

design a kind of semiconductor cold trap system independently. Via being thickening treatment samples can be measured 100 %

which can increase sensitivity of measurement. Compared to other pre-treatment methods

it has advantages of simple structure

cooling quickly

easy to maintain and control. Experimental results show that the system is stable and reliable. By detecting 5 kinds of different volume fraction of ethanol and formaldehyde

when average error of ethanol detecting is 0. 44 × 10

- 6

and to formaldehyde

it is 0. 36 × 10

-6

so the test results meet the needs.