Solid Phase Dansylation Coupled With LC-MS For The Determination Of Phenolic Compounds In Environmental Samples

A method consisting of solid-phase isotope dansylation and liquid chromatography-high resolution mass spectrometry（LC-HRMS）was developed for the quantitative analysis of phenolic compounds（phenols）in environmental samples.Magnetic-HLB（hydrophilic lipophilic balanced）material was firstly synthesized and used as adsorbent for magnetic solid-phase extraction（MSPE）to enrich the analytical targets.With the solid-phase isotope labeling,the desalting and removal of labeling residuals could be simplified over conventional in-solution labeling.In addition to the overcoming of matrix effect by isotope dansylation,the sensitivity for the analysis of phenols by LC-HRMS was remarkably improved for over100-fold.The method was systematically evaluated,and good accuracy（86.5-104.9%）and precision（RSD of<8.6%and<11.4%for intra-and inter-day,respectively）were achieved for the tested 15 phenols.The limits of detection（LODs）of this method were estimated to be0.2-5 ng/L and 5-100 ng/kg in estuary water and sediment samples,respectively.With this method,samples collected from Daliao River estuary（Panjin,China）were analyzed.All the targeted phenols were detected at concentrations of unquantifiable to 485 ng/L（822-957 ng/L in total）and 15.7 to 1368 ng/kg（2251-2992 ng/kg in total）in water and sediment,respectively.Though there was no regulation of phenols in sea or estuary water,long term monitoring of the phenols in sea/estuary should be considered in the future as the total concentration was close to the maximal allowable concentration（MPC）in surface water（1μg/L）.After quantifying the target with the developed method,start to study the treatment method of pollutants.The treatment of organic pollutants,advanced oxidation such as Fenton-like reactions were widely applied.However,for some compounds with high chemical stability,e.g.phenols,could not be fully oxidized to mineralization,and some new pollutants were generated.For the unknown pollutants,the identification of their chemical structure is the fundamental for the investigation of their environmental impact.As bisphenol A（BPA）was a typical phenolic compound,the structure contains unit phenols and dihydric phenols,the study of BPA can lay a foundation for the study of degradation products of other phenols,which was selected to investigate the oxidation process in Fenton-like reaction.In the reaction,zero-valent iron as iron source and H₂O₂as oxidant were applied under acidic conditions.After reaction,the resultant products were analyzed by LC-HRMS in negative full scan mode.By comparing the extracted chromatograms（XIC）before and after reaction,as well as the blanks,the new peaks were selected for product ion scan.From the XIC,it was found the oxidation process was very complex,and many isomers were presented.With the optimized LC gradient for isomers separation and collision energy for product ion scan（MS²）,and assistance of deuterium coded BPA（BPA-D16）in the elucidation of product ions,finally,28new compounds from 14 different charge-to-mass（m/z）of were putatively identified.