Evaluation on the generative mechanism and biological toxicity of microcystin-LR disinfection by-products formed by chlorination

Abstract To control the environmental risk of microcystin-LR disinfection by-products (MCLR-DBPs), we evaluated their generative mechanisms and biological toxicity by mass spectrometry technology and protein phosphatase inhibition assay. Subject to chlorination, MCLR was totally transformed within 45 min and generated 5 types of MCLR-DBPs with the chemical formulas of C 34 H 54 N 10 O 12 , C 49 H 76 N 10 O 14 Cl 2 , C 49 H 77 N 10 O 15 Cl, C 49 H 75 N 10 O 13 Cl, and C 49 H 76 N 10 O 14 . Isomers for each MCLR-DBP type were identified and separated (products 1–9 ), indicating that the conjugated diene in Adda residue was a major target site of disinfection. Though, subsequent toxicity test showed the toxicity of MCLR-DBPs on protein phosphatase 1 decreased with the extending of disinfection by and large, these DBPs still possessed certain biological toxicity (especially for product 5 ). Combined with quantitative analysis, we thought the secondary pollution of MCLR-DBPs in drinking water also deserved further attention. This study offers valid technique support for MCLR-DBPs identifiation, contributes to a comprehensive cognition on their hazard, and thus has great significance to prevent and control the environmental risk induced by microcystins and their DBPs.