Nontarget Analysis of Disinfection Byproducts Using Sequential Extraction and Elution

Disinfection byproducts (DBPs) formed upon drinking water treatment are often cytotoxic and genotoxic, and have been related to health risks, such as bladder cancer. Large DBPs, with more than two carbon atoms, are produced in large quantities and great diversity, and contribute substantially to observed toxicity, but their composition and structure remain largely unknown. While a few studies have explored high-resolution detection methods, we here focus on the extraction and elution procedures of these >2 carbon DBPs, before using negative electrospray ionization (ESI[−]) and detection by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Samples were collected from three drinking water treatment plants (DWTPs) in Sweden, of which two use hypochlorite and one uses monochloramine for disinfection. A reversed-phase SPE sorbent (Hyper Sep) showed high complementarity with a hybrid carbon sorbent (Carbon S), which captured a subset of polar saturated DBPs not retained by the commonly used reversed-phase materials. Stepwise elution using solvents of varying polarity reduced sample complexity and ionization suppression and further extended the DBP diversity detected. Extraction at pH 8, investigated for one DWTP, also extended DBP diversity but that impact was smaller. The classic methanol elution on reversed phase may miss proportionally more DBPs in chloraminated drinking water.