A simple, low-cost, remote fiber-optic micro volume fluorescence flowcell for capillary flow-injection analysis

A small volume flowcell for fluorescence detection in capillary flow injection (CFI) analysis has been created by using a low cost, commercially available fluidic device. Fluorescence detection is achieved using an optical fiber to deliver excitation light to the sample flowing through the device and another optical fiber to collect fluorescence emission. The flowcell is a standard fluidic cross with a swept volume of 721 nL. Optical fibers were oriented at right angles using standard sleeves and ferrules to set their position near the cross intersection. Multiple excitation sources were used including a low power UV laser and blue and UV light emitting diodes (LED). The full emission spectrum detection limits, using the laser, for fluorescein and bovine serum albumin (BSA) were 0.30 ppb and 2.1x10(-4)% (w/w), respectively. Two fluidic crosses were used in series for multi-wavelength fluorescence excitation using fiber-optically coupled LED.