Isotachophoretic separations on a microchip. Normal Raman spectroscopy detection.
Isotachophoretic separations of the herbicides paraquat and diquat are performed in a glass microchip etched channel and monitored on-chip by normal Raman spectroscopy. The 40-micron-wide and 75-micron-deep separation channels are chemically etched in a serpentine design to 21-cm total length. A 120-micron-thick glass cover slip is used to seal the channels. Separation field strengths up to 380 V/cm are used. The microchip is directly coupled to a Raman microprobe. No interfacing is required. Raman spectra are generated with a 2-W, 532-nm NdY-VO4 laser and collected at 8-cm-1 resolution with a holographic transmissive spectrograph and a cryogenically cooled CCD. Data acquisition is at 2-5 spectra/s. Raman isotachopherograms of the pesticides at starting concentrations as low as 2.3 x 10(-7) M (60 ppb paraquat/80 ppb diquat) are presented.
Walker
P A
PA
Department of Chemistry, University of Michigan, Ann Arbor 48109-1055, USA.
Morris
M D
MD
Burns
M A
MA
Johnson
B N
BN
D004178:Diquat / Q000032:analysis; D004586:Electrophoresis / Q000295:instrumentation* / Q000379:methods; D006540:Herbicides / Q000032:analysis / Q000302:isolation & purification; D007202:Indicators and Reagents; D008904:Miniaturization; D010269:Paraquat / Q000032:analysis / Q000302:isolation & purification; D013059:Spectrum Analysis, Raman / Q000295:instrumentation* / Q000379:methods
D006540:Herbicides; D007202:Indicators and Reagents; D004178:Diquat; D010269:Paraquat