A novel fluorometric chemosensor based on imidazo[4,5-b]phenazine-2-thione for ultrasensitive detection and separation of Hg2+ in aqueous solution

We synthesize and develop 1,3-dihydro-2H-imidazo[4,5-b]phenazine-2-thione as a ratiometric chemosensor for recognition of Hg²⁺ in DMSO/H₂O (v/v = 9:1) binary solution. We rationally introduce the phenazine imidazole group as fluorophore and the thione moiety as recognition site to bind Hg²⁺. Interestingly, the chemosensor shows ultrasensitive response for Hg²⁺ and the lowest limit of detection is 0.167 nM. In addition, it can also separate Hg²⁺ from aqueous solution with excellent ingestion capacity, and the adsorption ratio is up to 96%. Furthermore, ion test strips based on the chemosensor are fabricated to conveniently and efficiently detect Hg²⁺.

The Use of Fluorescence Spectra for the Detection of Scab and Rot in Fruit and Vegetable Crops

Using Fluorescence Spectrometer Lumina, fluorescence spectra of surface slices of apples and potatoes were measured. Some of the samples were healthy, some were infected: apples had scabs, potatoes had rot and mechanical damage. For apples, two zones were found where the emission spectra of healthy and scab-affected samples differed significantly from each other. This is the region of 400–450 nm with excitation of 300–350 nm, as well as the region of 680–750 nm with excitation of 400–450 nm. For potatoes, the differences between a healthy and rot-affected sample were found only in the region of 400–450 nm with excitation at 300–350 nm. The found differences are clearly manifested in the correlation coefficients between the spectra - the minimum correlation coefficient for healthy apples and scab at 450 nm excitation r = 0.51. Also, healthy and diseased samples are well separated using principal component analysis (PCA). The revealed differences in the fluorescence spectra can be used for the detection and separation of diseased and healthy fruits and vegetables.