Cyanide fishing, which though outlawed, is still practiced in the Philippines and Indonesia, involves the use of a solution of sodium cyanide squirted around coral reefs to stun and capture reef fish.The ability to detect if a fish was exposed to cyanide during capture is a major goal of the marine aquarium trade. A promising technique was proposed, the use of an HPLC with a C30 column treated with polyethylene glycol and a UV detector operating at 220 nm to detect thiocyanate in aquaria water of fish exposed to cyanide.However, we have not been able to detect thiocyanate in aquaria water. We have readily observed thiocyanate in the plasma of fish exposed to cyanide. Preliminary results indicate a half-life of thiocyanate on the order of 4-8 days when Amphiprion ocellaris is exposed to cyanide. At present we have not been able to observe thiocyanate in fish beyond 8 days post exposure or quantify thiocyanate beyond 4 days because of spectral interferences from the plasma matrix. In this study we will use HPLC to determine the half-life of thiocyanate in a different species, Haemulon chrysargyreum, or Smallmouth Grunt Fish. The fish will be exposed to 25 ppm aqueous sodium cyanide for 60 seconds and blood will be collected in microchematocrit tubes by caudal severance at regular intervals up to 32 days post exposure. The tubes will be spun to separate the plasma, and the collected plasma will be evacuated into microcentrifuge tubes and stored at -80oC pending analysis. Just prior to analysis, 400 mL of cold acetonitrile will be added to the plasma and then centrifuged to remove proteins. 400 mL of supernatant will be removed, and blown dry over warm nitrogen. The samples will be reconstituted in 400 mL HPLC grade water and then injected directly into the HPLC for determination of SCN-. In determining the half-life of Haemulon chrysargyreum, we will be able to estimate how long after capture this method would prove to be a viable option for the detection of cyanide exposure.

Determination of the half life of thiocyanate in the plasma of Haemulon chrysargyreum (smallmouth grunt fish) exposed to potassium cyanide

255th National Meeting (2018)

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