For laser-induced fluorescence (LIF)
detection, a 50 mW beam from a variable power 488 nm 150 mW diode
pumped solid state laser (Sapphire, Coherent, Santa Clara, CA) was
expanded to a ∼2.5 cm wide by ∼150 μm thick line
across the μFFE separation channel. To investigate broadening
effects, replicate separations were performed with the detection line
positioned several distances from the top of the separation channel.
For on-capillary detection, a window was burned in a 360 μm
O.D., 20 μm I.D.
fused silica capillary (Polymicro Technologies,
Phoenix, AZ) and positioned under the laser line.
Fluorescence
imaging across the separation channel was performed using a Prime
BSI Express camera (Teledyne Photometrics, Tucson, AZ) mounted on
an
AZ 100 stereomicroscope (Nikon, Tokyo, Japan) with a 0.5×
objective. Fluorescent dye separations were imaged using an exposure
time of 200 ms and an Endow GFP filter cube (Nikon) containing a dichroic
mirror (495 nm cutoff) and a 500–550 nm band-pass filter. Separations
of Chromeo P503-labeled proteins were imaged using an exposure time
of 500 ms and a custom filter cube (Nikon) containing a dichroic mirror
(500 nm cutoff) and a 570–640 nm bandpass filter.
Douma C.C, & Bowser M.T. (2023). Assessing Surface Adsorption in Cyclic Olefin Copolymer Microfluidic Devices Using Two-Dimensional Nano Liquid Chromatography-Micro Free Flow Electrophoresis Separations. Analytical Chemistry, 95(50), 18379-18387.