Activity Analysis of Iron in Water Using a Simple LED Spectrophotometer

Access to clean water is a vitally important part of the lives of all people, yet there is often a concern about the contamination of water by heavy metals. The detection and measurement of heavy metals in water can be performed using colorimetric reagents paired with ultraviolet–visible light (UV–vis) spectrophotometry. The presented activity includes construction of a simple, inexpensive single-wavelength spectrophotometer using LEDs as the light source and detector. Using a colorimetric reagent, 2,4,6-tripyridyl-s-triazine, the concentration of iron can be measured by the LED spectrophotometer. Multiple natural water samples were collected and analyzed by this technique, and the performance of the LED spectrophotometer was compared to that of a conventional UV–vis spectrophotometer. The LED spectrophotometer had comparable results to those of the conventional UV–vis spectrophotometer while teaching students about simple circuit design, spectroscopy, and water quality measurements.