A handheld smartphone-controlled spectrophotometer based on hue to wavelength conversion for molecular absorption and emission measurements

摘要

An improved design for a handheld smartphone-based spectrometer that works in both absorption and emission modes is proposed. The device, named Spectrophone, comprises modules made in MDF, an embedded light source designed for absorption mode, a DVD for the diffraction grating, and a smartphone to process the image data acquired. A user-friendly homemade software decompose the pixels from shots of spectral images into their RGB and hue (H) values which are processed by a simple algorithm developed to convert H values to their corresponding wavelengths. Analytical signals for the absorption mode are provided by an empirical equation based on RGB vector norms (‖vRGB‖) taken in blank and after light absorption, while ||vRGB|| is directly used to acquire emission signals. The Spectrophone was applied to determine Fe2+ in medicine samples and Na+ in saline solution and natural water samples. No statistically significant differences were observed in comparison with commercial instruments (α = 5%). The figures of merit of the Spectrophone were very good, with limits of quantification of 70 μg L-1 for absorption and 60 μg L-l emission modes, respectively, and high linearity (R2 >0.9995). High accuracy, simplicity, a user-friendly application and low-cost make this handheld device an attractive alternative for the absorption/emission measurements.