Reliable Determination of Cyanide in Water—A Modest Proposal
Oral Presentation
Prepared by M. Delaney, C. Blodget
Massachusetts Water Resources Authority (MWRA), 190 Tafts Ave, Central Laboratory, Winthrop, MA, 02152, United States
Contact Information: mike.delaney@mwra.com; 617-660-7801
ABSTRACT
Reliable determination of cyanide in water samples is important for both wastewater and drinking water treatment plant operators and regulatory agencies, but due to cyanide’s diverse chemistry that has been problematic. A variety of chemical mechanisms can form or destroy cyanide and some of these can occur within the sample container or during laboratory pretreatment and analysis, leading to biased results. EPA acknowledged this difficulty in the 2012 Methods Update Rule by revising the footnote for cyanide preservation to include the following: “There may be interferences that are not mitigated …any technique for removal or suppression of interference may be employed, provided the laboratory demonstrates that it more accurately measures cyanide through quality control measures described in the analytical test method.” We will present data demonstrating how quality control measures can show the mitigation of cyanide interferences. This will include using a gentler analysis method, avoiding preservation steps that are problematic, and the use of field spikes to demonstrate sample integrity.
Oral Presentation
Prepared by M. Delaney, C. Blodget
Massachusetts Water Resources Authority (MWRA), 190 Tafts Ave, Central Laboratory, Winthrop, MA, 02152, United States
Contact Information: mike.delaney@mwra.com; 617-660-7801
ABSTRACT
Reliable determination of cyanide in water samples is important for both wastewater and drinking water treatment plant operators and regulatory agencies, but due to cyanide’s diverse chemistry that has been problematic. A variety of chemical mechanisms can form or destroy cyanide and some of these can occur within the sample container or during laboratory pretreatment and analysis, leading to biased results. EPA acknowledged this difficulty in the 2012 Methods Update Rule by revising the footnote for cyanide preservation to include the following: “There may be interferences that are not mitigated …any technique for removal or suppression of interference may be employed, provided the laboratory demonstrates that it more accurately measures cyanide through quality control measures described in the analytical test method.” We will present data demonstrating how quality control measures can show the mitigation of cyanide interferences. This will include using a gentler analysis method, avoiding preservation steps that are problematic, and the use of field spikes to demonstrate sample integrity.
