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Description: Advancing Cyanide Monitoring
Advancing Cyanide Monitoring
Protecting municipal water supplies from cyanide contamination is paramount for global public health. The U.S. Environmental Protection Agency (EPA) regulates cyanide and provides guidelines for its measurement in drinking water, surface water, and wastewater. EPA defines total cyanide as free cyanide and hydrocyanic acid, as well as ferrocyanide and ferricyanide, which can form free cyanide when exposed to light. For drinking and surface waters, EPA has established a maximum contamination level (MCL) of 200 ?g/L free cyanide, determined by a total cyanide assay. For wastewater, discharge limits vary by the type of industry and the size of the facility.
Author(s)
Terri Christison
SourceWater Environment & Technolology
Subjecthigh-strength waste; microconstituents
Document typeMagazine article
PublisherWater Environment Federation
Print publication date Jan 2020
Volume / Issue32 / 1
Content sourceWorld Water Magazine
First / last page(s)46 - 49
Copyright2020
Word count1,874
Subject keywordshigh-strength wastemicroconstituentsion chromatographycontaminants

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Description: Advancing Cyanide Monitoring
Method Choiced
Advancing Cyanide Monitoring
While EPA has approved several methods for cyanide determination, these methods are often complex, requiring cyanide compounds to be converted to hydrogen cyanide gas first and then distilled before total cyanide can be determined. Using these methods also introduces potential ion interference, which can affect measurement accuracy.
PublisherWater Environment Federation
Copyright2020
Word count96
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Description: Advancing Cyanide Monitoring
Many Methods
Advancing Cyanide Monitoring
Several analytical methods have been developed to determine cyanide in water. EPA methods 335.2, 335.3, and 335.4 detail the measurement of total cyanide concentration. In each of these methods, collected water samples undergo acid- or UV-digestion to convert cyanide compounds to hydrogen cyanide gas, which is then distilled into sodium hydroxide. The total cyanide concentration is determined...
PublisherWater Environment Federation
Copyright2020
Word count280
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Description: Advancing Cyanide Monitoring
Increasing Accuracy
Advancing Cyanide Monitoring
Ongoing improvements in ICE and PAD technologies support more accurate, sensitive, and selective total cyanide measurements. With their speed and operational robustness, these advanced systems are helping to generate reliable results more efficiently, too.
PublisherWater Environment Federation
Copyright2020
Word count163
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Description: Advancing Cyanide Monitoring
Case Study Using ICE–PAD
Advancing Cyanide Monitoring
A recent study case demonstrated the effectiveness of modern ICE–PAD systems. This application was designed to assess the suitability of ICE–PAD for total cyanide measurement in water samples.
PublisherWater Environment Federation
Copyright2020
Word count35
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Description: Advancing Cyanide Monitoring
Streamlining Sample Preparation
Advancing Cyanide Monitoring
Using a single system for the collection and distillation of samples can improve workflow efficiency by eliminating the need for multiple time-consuming preparation and distillation steps. As free cyanide is reactive and unstable, water samples were stabilized at the time of collection with sodium hydroxide. Collection tubes were pre-rinsed with 1 mL of 7.11 molar (M) sulfuric acid and 0.75 M...
PublisherWater Environment Federation
Copyright2020
Word count213
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Description: Advancing Cyanide Monitoring
Reducing Limit of Detection
Advancing Cyanide Monitoring
The improved limit of detection offered by PAD enables reliable and consistent measurement of cyanide at low levels, improving the sensitivity of municipal water safety testing. Cyanide was separated by ICE using 50 mM methanesulfonic acid at a flow rate of 0.2 mL/min and was detected by PAD using a platinum disposable working electrode optimized for acidic eluents. Samples were compared to a 5...
PublisherWater Environment Federation
Copyright2020
Word count232
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Description: Advancing Cyanide Monitoring
Enhancing Precision
Advancing Cyanide Monitoring
The precision of the ICE–PAD method was evaluated using six replicate injections of a 5 μg/L cyanide standard, a 10-fold dilution of a cyanide certified wastewater (CWW) sample, CCW spiked with 5 μg/L cyanide, and municipal drinking water with 1 μg cyanide added. The method demonstrated high accuracy with average recoveries between 97.4% and 102%.
PublisherWater Environment Federation
Copyright2020
Word count251
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Description: Advancing Cyanide Monitoring
Reducing Ion Interference
Advancing Cyanide Monitoring
ICE chromatography delivered reliable results by eliminating ion interference, even at very low cyanide levels. The potential for false positives was evaluated using a method devised by the American Society for Testing and Materials (ASTM). This method assessed free cyanide levels in an undigested cyanate sample and a “challenge matrix.” The ASTM challenge matrix stock solution...
PublisherWater Environment Federation
Copyright2020
Word count176
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Description: Advancing Cyanide Monitoring
Robust Methodology
Advancing Cyanide Monitoring
Given the importance of obtaining reliable total cyanide measurements under different measurement conditions, the tolerability of the ICE–PAD method was assessed. The effects of different platinum working electrodes, eluent concentrations, column temperatures, and column lots on the measured cyanide peak response and retention time are highlighted in the table below. The greatest effect on...
PublisherWater Environment Federation
Copyright2020
Word count300
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Advancing Cyanide Monitoring