Evaluation of the performance of 3D printed (spectro)photometers based on multi-channel color sensors for colorimetric determinations.

Portable and affordable (spectro)photometers based on digital color sensors are gaining significance in analytical chemistry due to their compact design, cost-effectiveness and integration capabilities. Despite their inherent straight-forward operation, various digital light sensors with distinct performance and optical characteristics are available on the market. For instance, AS7341 and AS7262 are multi-channel color sensors that covers eight and six spectra regions, respectively, while TCS34725 operates using three channels (red, green, and blue). In this study, the analytical performance of 3D printed, reflectance-based (spectro)photometers employing different digital color sensors was evaluated. Spectra resolution, signal gain and LED current were systematically evaluated to ensure the best performance for each sensor. The sensors' analytical performance was obtained by quantifying different dyes in aqueous solutions and sunset yellow in beverages as a proof-of-concept. All three sensors presented sub-millimolar detection with excellent linear coefficient (r² > 0,99) and sensitivity comparable to a conventional spectrophotometer. In the quantification of sunset yellow (λ_max = 480 nm) in the presence of tartrazine (λ_max = 430 nm), the AS sensors showed enhanced sensitivity and linearity, minimizing the spectral overlapping. Their versatility and cost-effectiveness make them ideal for real-time, portable applications. Furthermore, their compatibility with microcontrollers and capability for wireless data transmission enhance their utility across diverse analytical environments.