Compact optoelectronic flow-through device for fluorometric determination of calcium ions

A low-cost and compact complete fluorometric detector dedicated for measurements under conditions of flow injection analysis has been developed. This device is fabricated by integration of light emitting diodes (LEDs) applied in the double role: as the source of light inducing fluorescence and as the detector of light emitted by excited fluorescent analyte. The device is made of three LEDs only, without any additional fibers, filters and lenses. The LEDs are integrated in the form of flow cell of 0.060 mL internal volume. The developed detector has been tested in simple flow injection manifold dedicated for fluorometric determination of calcium using calcein method. The system offers sensitive and selective determination of calcium at ppm levels with relatively high flow throughput (near 60 injections per hour) and satisfactory reproducibility. The practical utility of developed detector has been confirmed by its application for analysis of mineral waters, medicines as well as physiological fluids.