Light-emitting diodes as sensors for colorimetric analyses

A new nondispersive colorimetric analyzer has been developed with the use of light-emitting diodes (LEDs) as optical sensors coupled to an artificial neural network (ANN). In this application, various colored LEDs are used as optical detectors with tuned bandpasses. The device has been evaluated against conventional spectrometric methods in the determination of pH and heavy metals by the use of colorimetric procedures. The spectrometer benefits from a simple design, ease of application, inexpensive cost of construction, and long life.