Highly sensitive fluorescent sensor based on electrosynthesized poly(Fmoc-l-serine) enables ultra-trace analysis of Cr2O72− in water and agro-product samples

A fluorescent sensor based on the electrosynthesized conjugated polymer poly(Fmoc- l -serine) ( PFOLS ) for highly sensitive analysis of Cr 2 O 7 2− at ultra-trace levels in water and agro-product samples was reported. PFOLS was obtained by potentiostatical electropolymerization of corresponding monomer Fmoc- l -serine in CH 2 Cl 2 -boron trifluoride diethyl etherate system. The introduction of serine group in PFOLS efficiently avoided the interference of anions and other acid substances in agro-products. Although metal ion Fe 3+ could also quench the fluorescence of PFOLS , EDTA could recover the fluorescence of PFOLS -Fe 3+ system. So in the presence of EDTA, PFOLS had a high-selectivity to Cr 2 O 7 2− and it could detect Cr 2 O 7 2− in linear ranges of 80 pM to 1.95 mM with a low detection limit of 72 pM. Then PFOLS was used to detect Cr 2 O 7 2− in water samples (tap water, lake water, and wastewater) and agro-product samples (white rice, red rice, and black rice) with satisfactory results, revealing that PFOLS could be as a practical sensing platform for ultra-trace analysis of Cr 2 O 7 2− in environment and agro-product samples.