Despite their status of being widely used as food additives, bisulfite (HSO₃–)/sulfite (SO₃²–) can pose serious health risks when they are excessively added. Therefore, it is vital to develop a new method for detecting HSO₃–/SO₃²– in foodstuff. In this paper, a benzopyran-benzothiazole derivative (probe DCA–Btl) with near-infrared emission was designed and synthesized by constructing a “push-pull” electronic system. DCA–Btl can selectively recognize HSO₃–/SO₃²– via a colorimetric and fluorescence dual channel in DMF/PBS (1:1, v/v, pH = 8.4), and the emission wavelength of DCA–Btl can reach 710 nm. The fluorescence quenching of DCA–Btl after recognition of HSO₃– is attributed to the photoinduced electron transfer (PET) process of the adduct DCA–Btl-HSO₃– as evaluated by the DFT/TD-DFT method. In addition, DCA–Btl has many advantages, including a large Stokes shift (95 nm), good anti-interference ability, and little cytotoxicity. What’s more, DCA–Btl has been successfully applied for the detection of HSO₃–/SO₃²– in actual water samples and food samples such as sugar, red wine, and biscuits with satisfying results, as well as for fluorescent imaging of HSO₃– in living MCF-7 cells.

A novel solid phase extraction procedure for determination of copper, lead and iron in natural water and food samples has been established in the presented work. 1-Phenylthiosemicarbazide (1-PTSC) as ligand and Dowex Optipore L-493 resin as adsorbent were used in a mini chromatographic column. Various analytical conditions for the quantitative recoveries of analyte ions including pH, amounts of adsorbent, eluent, sample volume, etc. were investigated. The recovery values for analyte ions were higher than 95%. The determination of copper, lead and iron was performed by flame atomic absorption spectrometry. The influences of some alkali, alkali earth and transition metals on the recoveries of analyte ions were investigated. The preconcentration factor was 62.5. The limit of detections of the understudied analytes (k=3, N=21) were 0.64μgL⁻¹ for copper, 0.55μgL⁻¹ for lead and 0.82μgL⁻¹ for iron. The relative standard deviation was found to be lower than 6%. The accuracy of the method was confirmed with certified reference material (GBW 07605 Tea). The method was successively applied for the determination of copper, lead and iron in water and some food samples including cheese, bread, baby food, pekmez, honey, milk and red wine after microwave digestion.