Flour moisture detection with an europium-based luminescent sensor

In this work, we describe the application of the self-assembled europium complex 1:Eu(III) (where 1: diethyl 8-methoxy-2-oxo-1,2,4,5-tetrahydro-cyclopenta[de]quinolin-3-yl)phosphonate) for the analysis of water content of wheat flour as well as from a variety of other food raw materials. The methodology herein described represents a robust and accurate way for the detection of small amounts of water in food, providing comparing results with well-established methods such as thermogravimetry and Karl-Fischer titration. Interestingly, as an advantage over other methods, our luminescent-based approach can be implemented in lab-on-a-chip microfluidic devices for real-time and on-line detection of water content of food samples. Additionally, the remarkably long luminescence lifetime of Eu(III) allows the use of state-of-the-art imaging strategies based on PLIM microscopy for the direct visualization of unique water content maps of flour grains.