Analytical chemistry is in the midst of a revolution. Borrowing concepts from the semiconductor industry, these scientists are fabricating micrometer-sized analytical devices on silicon, glass, or plastic substrates. The goal is portable, easy-to-use “lab-on-a-chip” devices, which contain complete analysis systems.

In this paper, Yuko Ueno, Hao-shen Zhou, and researchers from NTT Lifestyle and Environmental Technologies and the National Institute of Advanced Industrial Science and Technology, both in Japan, demonstrate a miniature device that quantitatively determines the individual components of airborne benzene, toluene, and xylene (BTX) mixtures. This group of volatile organic compounds has mutagenic and carcinogenic properties.

The device, which is just a proof-of-concept setup, consists of two 3 × 1 cm Pyrex cells—one for concentrating samples and the other for detection. The system also had peripheral components, such as a computer, battery, and spectrometer. BTX was concentrated on a mesoporous silica absorbent; the individual components of the mixture then were selectively desorbed off the absorbent by heating, and the concentration was determined by UV spectrophotometry. The researchers say that the total time to record each spectrum was 5 seconds.

To test their system, the scientists prepared a BTX sample with components set at 10-ppm levels and had their device collect samples for 30 minutes. They report a 0.05-ppm detection limit for toluene gas. (Anal. Chem. 2002, 74, 5257–5262)