PURPOSE: Cyanide is a fast acting, lethal agent. Exposure to cyanide can occur in a number of different events such as smoke inhalation, acts of terrorism and industrial accidents. Death can occur within minutes of exposure; therefore, development of a method for rapid diagnosis of cyanide toxicity is of great importance. Mass spectrometry, high-performance liquid chromatography, and spectrophotometry are the current methods to detect and quantify cyanide in blood. However, they take hours to perform as they require off-gassing and trapping of cyanide in its gaseous phase. We present a simple, rapid whole blood assay employing cobinamide and spectrophotometry without the use of toxic reagents or off-gassing of cyanide to detect cyanide in whole blood samples.
METHODS: After cyanide was added to whole blood to simulate cyanide exposure, cobinamide was added to the specimen and mixed for 3-5 minutes. Plasma was then separated. Absorbance was measured with a spectrophotometer and assessed for characteristic spectral changes of resultant dicyanocobinamide.
RESULTS: With the formation of dicyanocobinamide from the binding of cobinamide and cyanide, the absorbance peak at 580 nm predictably shifts with respect to the relative ratio of cobinamide and dicyanocobinamide concentrations in the specimen. A similar shift was reproduced in whole blood assays which require minimal equipment and non-toxic reagents. Correlation studies revealed that the cobinamide-based method was significantly more stable and consistent than DNB/NBA gold method for measuring cyanide levels in whole blood. Cyanide may be lost when the sample is gassed off in the DNB/NBA gold method. This loss may contribute to inaccurate and inconsistent measurements of cyanide levels in blood.
CONCLUSIONS: This study demonstrates the feasibility of a concept for the development of a rapid cobinamide-based cyanide assay to detect cyanide levels and toxicity in whole blood. With completion of standard assay curves, accurate, rapid CN assays can potentially be developed using cobinamide and simple spectophotometry in this approach. Future development of “dipstick” based field diagnostic testing kits may also be possible using these principles.
CLINICAL IMPLICATIONS: Development of a rapid cobinamide-based cyanide assay to detect cyanide levels and toxicity in whole blood
DISCLOSURE: The following authors have nothing to disclose: Asia Vo, Javier Longoria, William Blackledge, Isaac Yoshii, Tho Le, Robert Liou, Sari Mahon, Gerry Boss, Matthew Brenner
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