Cyanogen chloride precursor analysis in chlorinated river water

Area of Science:

• Environmental Chemistry
• Water Treatment Chemistry
• Organic Chemistry

Background:

• Amino acids are potential precursors for cyanogen chloride (CNCl), a disinfection byproduct in chlorinated drinking water.
• Identifying specific amino acid precursors is crucial for understanding and mitigating CNCl formation.

Purpose of the Study:

• To comprehensively identify amino acids that act as precursors to cyanogen chloride (CNCl).
• To quantify the contribution of glycine to CNCl formation in natural river water.
• To investigate the nature of non-glycine CNCl precursors.

Main Methods:

• Screening of 17 amino acids for CNCl yield.
• Chlorination of Huron River water samples with concurrent amino acid analysis and CNCl monitoring.
• Kinetic analysis of CNCl formation.
• Immobilized metal ion affinity chromatography (IMAC) to assess precursor characteristics.

Main Results:

• Only glycine among 17 tested amino acids yielded detectable CNCl.
• Glycine accounted for an estimated 42-45% of CNCl formed in Huron River water.
• CNCl formation exhibited both rapid (glycine-related) and slower pathways.
• IMAC experiments suggested non-glycine precursors are not proteinaceous and may be humic/fulvic substances.

Conclusions:

• Glycine is a significant precursor to cyanogen chloride in chlorinated drinking water.
• Unidentified, non-proteinaceous precursors, likely from the humic fraction, also contribute to CNCl formation.
• Further research is needed to fully elucidate the role of organic matter in CNCl byproduct formation.