Studies On Disinfection Byproducts Of Aromatic Amino Acids In Chlorinated And Chloraminated Water (Part ?)

Disinfection of drinking water is an important measure to prevent waterborne diseases and is essential for human health.Chlorination or chloramination is the most extensive methods of drinking water disinfection.Amino acids(AAs),as the basic unit of protein,are widely distributed in surface water.AAs,especially aromatic AAs,are easily attacked by disinfectant(e.g.,chlorine and chloramines)during the water disinfection process.It will produce complex disinfection byproducts(DBPs),which might do severely harm to human health.Therefore,it is very important and necessary to study on the DBPs generated from aromatic AAs in the drinking water disinfection process.The studies on the DBPs of tyrosine(Tyr)and phenylalanine(Phe)in the chlorinated or chloraminated water were carried out base on UHPLC-Q-TOF HRMS in the paper.In addition,the chloramination reaction kinetics of the two aromatic AAs was performed base on UHPLC-QQQ MS.A UHPLC-Q-TOF HRMS method for the detection of Tyr,Phe and their DBPs was established and optimized.The chlorination DBPs of the two aromatic AAs were studied respectively.Phe,3-Cl-Tyr,3,5-di-Cl-Tyr,N-Cl-Tyr,3,N-di-Cl-Tyr and 3,5,N-tri-Cl-Tyr were identified as the chlorination DBPs of Tyr and N-Cl-Phe of Phe.The variation of these DBPs with different amounts of sodium hypochlorite and the time of disinfection were also studied.Seventeen DBPs of Tyr and 17 DBPs of Phe were detected respectively in the chloraminated water.Phe,p-OH-benzaldehyde,p-OH-phenylacetamide and N-Cl-Tyr were identified as the chloramination DBPs of Tyr.Benzamide,phenylacetamide,p-OH-phenylacetamide and N-Cl-Phe were identified as the chloramination DBPs of Phe.The other DBPs of Tyr and Phe were proposed as diazonium,hydrazone,amidine,amide,peroxide or the compounds with more complex structure based on the molecular formula generated from the accurate mass measurement and the MS/MS spectra.The variation of these DBPs with different amounts of monochloramine and the time of disinfection were also studied.A UHPLC-QQQ MS method for the quantitative analysis of Tyr and Phe was also established and optimized.The system suitable tests of the method were performed.Then the pseudo-first-order kinetics reaction constants of chloramination of Tyr and Phe at 4,13,22,31,40 ? were measured,respectively.Furthermore,the active energy of the chlorination disinfection reaction of Tyr and Phe was calculated based on the Arrhenius Equation.It was 63.077 kJ/mol for Tyr and 63.609 kJ/mol for Phe.The results of our researching in this paper will benefit for the manufacture and the quality standard formulation of the drinking water.