Standard Article

Cyanogen Chloride and Cyanogen Bromide Analysis in Drinking Water

Environment: Water and Waste

  1. Yuefeng Xie1,
  2. Cordelia J. Hwang2

Published Online: 15 SEP 2006

DOI: 10.1002/9780470027318.a0809

Encyclopedia of Analytical Chemistry

Encyclopedia of Analytical Chemistry

How to Cite

Xie, Y. and Hwang, C. J. 2006. Cyanogen Chloride and Cyanogen Bromide Analysis in Drinking Water. Encyclopedia of Analytical Chemistry. .

Author Information

  1. 1

    The Pennsylvania State University at Harrisburg Middletown, USA

  2. 2

    Metropolitan Water District of Southern California, La Verne, USA

Publication History

  1. Published Online: 15 SEP 2006

Abstract

Cyanogen chloride (CNCl) (CAS 506-77-4) is a common disinfection by-product DBP formed in chloraminated waters. Cyanogen bromide (CNBr) (CAS 506-68-3), the brominated analog of CNCl, is formed in chloraminated or ozonated waters that are high in bromide. Both CNCl and CNBr are labile in drinking water. They undergo degradation reactions at high pHs or in the presence of free chlorine or sulfite. Because of its potential health effects, CNCl was included in the United States Environmental Protection Agency (USEPA) Information Collection Rule (ICR). Aqueous standards for CNCl are generally prepared with pure CNCl gas. They can also be prepared with chlorinated or chloraminated cyanide (CN) solutions. Aqueous standards for CNBr are prepared with commercially available CNBr. For sample preservation, ascorbic acid is commonly used to quench the residual chlorine or chloramines. Acid is often added to lower the pH to prevent possible hydrolysis degradation. There are three methods for analyzing CNCl and CNBr in drinking water samples: purge-and-trap gas chromatography/mass spectrometry (PT GC/MS), headspace gas chromatography/electron-capture detection (GC/ECD), and micro liquid–liquid extraction gas chromatography/electron-capture detection (LLE GC/ECD). All three methods are capable of analyzing microgram per liter levels of CNCl and CNBr in drinking water, and all three give similar method performance, including accuracy, precision, spiking recovery, and method detection limit. The PT GC/MS method is a modification of the USEPA Method 524.2, which requires the use of specialized instrumentation. Because of CNBr's low vapor pressure and high water solubility, the analysis of CNBr also requires a heated purge. Headspace GC/ECD method is a relatively simple and rapid analytical method. As the samples are prepared individually, the method requires a full-time analyst to prepare and inject each sample. However, this analytical procedure can be automated using a commercially available headspace autosampler. In general, micro LLE GC/ECD is a well developed and common procedure for DBP analysis. The micro LLE GC/ECD method, originally developed for CNBr analysis, has been further developed for both CNCl and CNBr analysis in drinking water. The sample injection generally is automated with a common gas chromatography (GC) autosampler.