Factors affecting atrazine concentration and quantitative determination in chlorinated water

Area of Science:

• Environmental Chemistry
• Analytical Chemistry

Background:

• Atrazine is a widely used herbicide.
• Previous studies indicated no significant reaction between atrazine and free chlorine during water treatment.

Purpose of the Study:

• To investigate atrazine transformation in drinking water under conditions simulating distribution system residence times.
• To assess the impact of this transformation on analytical quantification methods for atrazine.

Main Methods:

• High-performance liquid chromatography-electrospray mass spectrometry (HPLC-ESI-MS) was used for detection.
• The study examined the effects of chlorine concentration, pH, and reaction time.
• Different dechlorinating agents and analytical instruments were evaluated for their impact on atrazine determination.

Main Results:

• Atrazine transformation was observed at drinking water distribution system residence times, forming N-chloro atrazine.
• The accuracy of atrazine quantification was significantly affected by the choice of dechlorinating agent (e.g., sodium sulfite, ascorbic acid) and pH.
• Inaccurate quantification, ranging from 2-fold to 30-fold errors, was observed with reductive dechlorinating agents.

Conclusions:

• Atrazine can degrade in drinking water, affecting monitoring accuracy.
• HPLC/UV with ammonium chloride quenching is recommended for precise atrazine quantification.
• Current analytical methods using specific quenching agents may lead to errors in compliance monitoring and health studies.