Development of a gas absorption microchip using porous glass and its evaluation for analytical applications

The possibility of a micro-total analysis system (mu-TAS) for high-speed, c onvenient and efficient analytical measurements has been suggested in recen t years. Its application in the monitoring of human health related to envir onmental species has become a worldwide issue. We have developed a measurem ent method with a microchip-based simple sampling procedure that obeys Fick 's and Henry's laws. It is suitable for measuring trace amounts of air poll utants and for monitoring and evaluating the living environment. The absorp tion solution, composed of 3% triethanolamine (TEA) solution, was used as a n absorption solution and flowed into the fabricated microchip. Gaseous NO2 , which dispersed through the porous glass material, was absorbed into the absorption solution. The influences of the flow rate of the absorption solu tion (0.2 similar to 0.6 ml/h) and the wind speed (0 similar to 2.5 m/s) in side a wind tunnel were studied under a NO2 concentration range of 10 simil ar to 150 ppb. It was shown that the concentration of NO2 in a sampling sol ution under a wind speed of 2.5 m/s was 20-times larger than that under a w ind speed of 0 m/s when the concentration of NO2 inside the wind tunnel was fixed at 50 ppb. This sampling method was proved to be suitable for measur ing of atmospheric NO2, and may also be used for sampling and evaluating th e indoor environmental NO2 level.