A portable, low-cost, LED fluorimeter for middle school, high school, and undergraduate chemistry labs

A low-cost portable fluorimeter was constructed using a 360 nm LED for excitation and a silicon photodiode for detection. The instrument is simple to operate and has been used to investigate fluorescent whitening agents extracted from various brands of paper, to determine the linear range and limit of detection of quinine in various commercial tonic water samples, and to quantify the amount of vitamin B1 in commercial multivitamin supplements. The instrument is straightforward to construct and to use and facilitates the introduction and hands-on application of spectroscopy, fluorescence, and related topics in middle school, high school, and undergraduate laboratory courses.