Paired emitter-detector light emitting diodes for the measurement of lead(II) and cadmium(II)

A transmittance mode optical device based on using a reverse biased light emitting diode (LED) as light detector has been developed for colorimetric analysis. This new optical device was validated with bromocresol green dye for absorbance measurements before being employed for detecting cadmium(II) and lead(II) in water. Results show that the performance of this LED-based device is comparable to much more expensive bench top UV–vis instruments, but with the advantages of being low cost, low power and simple to operate.