Fluorometric determination of sulfide ions via its inhibitory effect on the oxidation of thiamine by Cu(II) ions
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A fluorometric assay is described for sulfide ions determination. It is based on the finding that the oxidation of the non-fluorescent substrate thiamine (TH) by Cu(II) in basic solution to form fluorescent thiochrome is inhibited by sulfide ions. This results in a decrease in fluorescence intensity which is proportional to the concentration of sulfide ions. Under the optimized conditions, the decrease in fluorescence, best measured at excitation/emission wavelengths of 370/440 nm, decreases linearly in the 0.03 to 2.5 μM sulfide ions concentration range. The detection limit is 20 nM. The method shows excellent selectivity over many potentially interfering ions and has been successfully applied to the determination of sulfide ions in spiked tap water, lake water and the synthetic wastewater samples. The method is time-saving and environmentally friendly, and in our perception shows a great potential in water quality inspection and environmental monitoring.
KeywordsFluorimetric assay Vitamin B1 Non-fluorescent substrate Anion detection Thiochrome Basic conditions Water samples
This work was financially supported by the National Natural Science Foundation of China (Grant No. 21705056), the Natural Science Foundation of Shandong Province (ZR2017MB022, ZR2018BB057 and ZR2018 PB009) and the start-up funding from University of Jinan (511-1009408, 511-1009424).
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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