Identification of Polar Drinking Water Disinfection By-products With LC/MS
Richardson, Susan D.
Caughran, Tashia V.
Crumley, F. Gene
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Alternative disinfectants, such as ozone, are gaining in popularity due to stricter regulations on chlorination by-products, namely trihalomethanes (THMs) and haloacetic acids (HAAs). However, there is still much not known about the identity of disinfection by-products (DBPs) from alternative disinfectants, such as ozone. And, therefore, it is not known if these alternatives form DBPs that are more or less harmful than those of chlorine. Because it is currently believed that many of the previously unidentified DBPs are polar in nature, and hence, difficult to extract from water and identify, we have developed a method that can be used to identify polar DBPs. This method involves the use of 2,4- dinitrophenylhydrazine (DNPH) derivatization followed by analysis with liquid chromatography (LC)/negative ionelectrospray mass spectrometry (MS), and will allow the identification of polar aldehydes and ketones in drinking water. This method offers advantages over the currently accepted method using pentafluorobenzylhydroxylamine (PFBHA) derivatization and gas chromatography (GC)/MS analysis. This DNPH-LC/MS method allows for the detection of highly polar carbonyl compounds (with multiple polar substituents) and produces mass spectra and chromatographic behavior that can be used to distinguish between aldehydes and ketones in ozonated water. Using this method, we have successfully analyzed many polar substituted aldehyde and ketone standards and have identified new DBPs from ozone that have not been previously reported