Development of micromachined preconcentrators and gas chromatographic separation columns by an electroless gold plating technology

In this study, a simple process for fabricating a novel micromachined preconcentrator ( μ PCT) and a gas chromatographic separation column ( μ SC) for use in a micro gas chromatograph ( μ GC) using one photomask is described. By electroless gold plating, a high-surface-area gold layer was deposited on the surface of channels inside the μ PCT and μ SC. For this process, (3-aminopropyl) trimethoxysilane (APTMS) was used as a promoter for attaching gold nanoparticles on a silicon substrate to create a seed layer. For this purpose, a gold sodium sulfite solution was used as reagent for depositing gold to form heating structures. The microchannels of the μ PCT and μ SC were coated with the adsorbent and stationary phase, Tenax-TA and polydimethylsiloxane (DB-1), respectively. μ PCTs were heated at temperatures greater than 280 °C under an applied electrical power of 24 W and a heating rate of 75 °C s⁻¹. Repeatable thermal heating responses for μ PCTs were achieved; good linearity ( R ²  >  0.9997) was attained at three heating rates for the temperature programme for the μ SC (0.2, 0.5 and 1 °C s⁻¹). The volatile organic compounds (VOCs) toluene and m -xylene were concentrated over the μ PCT by rapid thermal desorption (peak width of half height (PWHH)  <1.5 s); preconcentration factors for both VOCs are  >7900. The VOCs acetone, benzene, toluene, m -xylene and 1,3,5-trimethylbenzene were also separated on the μ SC as evidenced by their different retention times (47–184 s). (paper)