Study On Dual-mode Detection Of Chromatography And Spectrum Based On Reactive Hg²⁺ Fluorescence Probe

Heavy metal pollution is a prominent pollution category in the current global environmental governance.Mercury ion is one of the most common and most toxic heavy metal ions.It is very necessary to design and develop a simple and effective mercury ion detection method to monitor mercury ion in the environmental system.There are two different reaction mechanisms of mercury ion fluorescence probes reported so far:"reactive"probe and"chelating"probe.Because the reactant-type probe can be specifically bound to Hg²⁺and undergo irreversible chemical reactions to form a new product,the new product usually has a stable structure.Compared with the probe,its structure,conjugate system and substituent groups have been changed,which can be clearly distinguished from the probe in HPLC detection.Therefore,indirect detection of mercury ions in liquid phase can be conducted by detecting the new product.Color-changing fluorescence detection method is suitable for field detection,while laboratory detection can be performed by high performance liquid chromatography.In this paper,spectroscopic detection and high performance liquid chromatography detection modes are combined to achieve laboratory detection and field rapid detection,so as to have a better detection means.The probe Ds-l was prepared by reaction of 2-thiophenyl hydrazine with phenyl isothiocyanate.The reaction of probe Ds-l with Hg²⁺is basically free from other common ions.The response is rapid,reaching equilibrium within 2 seconds.Both mercuric ion concentration titration and HPLC can verify the concentration of mercuric ion in samples,and the relative error is less than 5%,indicating that the probe Ds-l can quantitatively detect Hg²⁺.However,due to the small conjugate system of the probe itself,there is no absorption in the visible range,and there is no fluorescence change before and after the identification of Hg²⁺,it cannot achieve rapid field detection.In order to make up for the deficiency of probe Ds-l,a probe By-m was prepared By reacting 7-diethylaminocoumarin-3-formylhydrazine with phenyl isothiocyanate.The recognition of Hg²⁺By Probe By-m is not affected by other common ions.The response of probe By-m and Hg²⁺is very rapid,and the equilibrium can be reached within 2 seconds.The color of Hg²⁺solution changed from dark yellow to light yellow significantly before and after the probe identification,which is suitable for field burst monitoring.When mercury-ion concentration titration and HPLC were used to verify the concentration of mercury-ion in samples,the relative error of spectral detection was less than 5%,while that of liquid chromatography was more than 5%,which indicated that the probe By-m could be used for the quantitative detection of Hg²⁺By spectroscopy,but the quantitative detection by HPLC needed to be further optimized.Finally,probe By-1 was synthesized By the reaction of probe SRh-NH with phenyl isothiocyanate.The recognition of Hg²⁺By Probe By-1 is not interfered by other common ions.The response of probe By-1 and Hg²⁺is very rapid,and the equilibrium can be reached within 2 seconds.The solution color changed from colorless to pink before and after the response of probe By-l and mercury ion,showing a very significant color change,which is suitable for rapid detection in the sampling field.Both mercuric ion concentration titration and HPLC can verify the concentration of mercuric ion in samples,and the relative error is less than 5%,indicating that the probe By-l can quantitatively detect Hg²⁺.By-l probe can detect contamination quickly and quantitatively by HPLC.In conclusion,it is feasible to use thiosemicarbazone structure as the reaction group to quantitatively and qualitatively detect mercury ions in samples by high performance liquid chromatography and spectroscopy,which can realize rapid laboratory detection and field detection.