Multifunctional Webcam Spectrophotometer for Performing Analytical Determination and Measurements of Emission, Absorption, and Fluorescence Spectra

Abstract

This paper reports the development and application of a low-cost multifunctional webcam spectrophotometer for the conduct of molecular absorption and fluorometric measurements. The equipment, which costs approximately US$20 to be fabricated, consists of a webcam, a diffraction grating, and a slit, all positioned inside an MDF box. Spectral measurements were carried out using the multifunctional equipment with the aid of a free software. The equipment was found to be suitable for conducting qualitative and quantitative analyses of fluorescence, absorption, and emission spectra and for analytical determinations in the spectral range of 380.00 to 1000.00 nm with 0.8 nm resolution. By simply changing the light radiation source, the equipment allowed us to determine the thermodynamic equilibrium constant of Alizarin Red S (1,2-dihydroxyanthraquinone-3-sodium sulfonate) and to obtain the fluorescence spectra of chlorophyll and anthocyanins (two natural pigments). The multifunctional spectrophotometer allows one to perform real-time spectral analysis, offers an easy and fast calibration process as an alternative to the commonly applied calibration approach by the diffraction grid equation, and does not require the use of lenses for beam collimation since the webcam lens itself performs this function. The equipment was successfully applied in experiments conducted by a class of 30 students from high school in a science fair to aid them in learning chemistry.