Temperature-programmed GC using silicon microfabricated columns with integrated heaters and temperature sensors.
Columns were fabricated in silicon substrates by deep reactive-ion etching. The channels were sealed with a glass wafer anodically bonded to the silicon surface. Heaters and temperature sensors were fabricated on the back side of each column chip. A microcontroller-based temperature controller was used with a PC for temperature programming. Temperature programming, with channel lengths of 3.0 and 0.25 m, is described. The 3.0-m-long channel was fabricated on a 3.2 cmx3.2 cm chip. Four columns were fabricated on a standard 4-in. silicon wafer. The 0.25-m-long channel was fabricated on a 1.1 cmx1.1 cm chip, and approximately 40 columns could be fabricated on a 4-in. wafer. All columns were coated with a nonpolar poly(dimethylsiloxanes) stationary phase. A static coating procedure was employed. The 3.0-m-long column generated about 12000 theoretical plates, and the 0.25-m-long channel generated about 1000 plates at optimal carrier gas velocity. Linear temperature ramps as high as 1000 degrees C/min when temperature programmed from 30 to 200 degrees C were obtained with the shorter column. With the 0.25-m-long column, normal alkanes from n-C5 through n-C15 were eluted in less than 12 s using a temperature ramp rate of 1000 degrees C/min. Temperature uniformity over the column chip surface was measured with infrared imaging. A variation of about 2 degrees C was obtained for the 3.0-m-long channel. Retention time reproducibility with temperature programming typically ranged from +/-0.15% to +/-1.5%. Design of the columns and the temperature controller are discussed. Performance data are presented for the different columns lengths.
Reidy
Shaelah
S
Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA. sreidy@umich.edu
George
Don
D
Agah
Masoud
M
Sacks
Richard
R
D002849:Chromatography, Gas / Q000295:instrumentation / Q000379:methods; D004566:Electrodes; D004867:Equipment Design; D006361:Heating / Q000295:instrumentation* / Q000379:methods; D012680:Sensitivity and Specificity; D012825:Silicon / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
D012825:Silicon