Analytical aspects of smart (phone) fluorometric measurements

Facing the problem of a growing number of analyses, the need for using simple equipment appears. Smartphone-based optical detection is one of the most widely applied ideas nowadays. A personal device such as a smartphone equipped with a camera is affordable even in the source-limited places. After a simple modification, providing the light source of both defined properties and orientation, a smartphone may become an efficient analytical device. In this work we present a uniform methodology of such a modification, offering a complete hand-held device for fluorometric measurements. Inducing the fluorescence of the tested analytes was done by ordinary light-emitting diodes, and phone camera was used as a detector. Then the obtained images were analyzed using the RGB colour model to get proper calibration curves. The demonstration of the system performing with the use of fluorescein preceded the examples of determination of quinine, rhodamine B, riboflavin and calcein in real-life circumstances. Example determinations of the calcium ions in mineral water and riboflavin in alcoholic beverages are provided. The results obtained with the designed device are fully comparable to the ones obtained with the conventional fluorometric equipment. The presented systems allow determination of all the investigated analytes with satisfactory detection limits, in some cases down to ppb levels. Thanks to the use of LEDs, the system could be adapted for both measuring and inducing fluorescence in different analytes, characterized by various excitation wavelengths.