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Proceedings of the International Cyanide Detection Testing Workshop

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levels with mV readings recorded as each<br />

level (Frakes and Studt 1996). Lead carbonate<br />

was added to <strong>the</strong> supernatant solution to<br />

precipitate sulfi des from solution. The<br />

fi rst trial compared readings with Atlantic<br />

Blennies, which were net-caught and exposed<br />

to cyanide. Both <strong>the</strong> test and <strong>the</strong> control<br />

fi sh (not exposed to cyanide) were found to<br />

exhibit cyanide levels <strong>of</strong> about 300 mg/L<br />

(ppm). Hence, <strong>the</strong> addition <strong>of</strong> lead carbonate<br />

to <strong>the</strong> solution prior to ISE testing did not<br />

eliminate <strong>the</strong> anomalously high readings. A<br />

second experiment evaluated whe<strong>the</strong>r <strong>the</strong> high<br />

readings might be due to iodide interference<br />

with <strong>the</strong> ISE. Again, <strong>the</strong> experiment was<br />

inconclusive. In a third experiment, test fi sh<br />

(4 Caribbean Blue Chromis, 1 Atlantic Wrasse,<br />

and 3 goldfi sh) were exposed to cyanide<br />

concentrations ranging from 1.3 to 3.9 ppm<br />

CN - for times ranging from one minute (for<br />

<strong>the</strong> 4 chromis) to 14 minutes (for a goldfi sh).<br />

Readings for control fi sh (1 wrasse and 2<br />

goldfi sh) not exposed to cyanide produced<br />

higher mV readings than fi sh exposed to<br />

cyanide.<br />

Recent analyses by Ms Benita Manipula using<br />

<strong>the</strong> Soundararajan procedure and cyanide<br />

measurements obtained using an Industrial<br />

Test Systems (ITS) Inc. colorimetric <strong>Cyanide</strong><br />

Reagent Strip TM (<strong>Cyanide</strong> Test Kit 484003) have<br />

also experienced diffi culty in obtaining reliable<br />

measurements <strong>of</strong> cyanide concentrations<br />

in comparison to known concentrations <strong>of</strong><br />

cyanide ion in sodium hydroxide solution<br />

(lacking slurry). The problem does not<br />

appear to be related to <strong>the</strong> reliability <strong>of</strong> <strong>the</strong><br />

151<br />

ITS cyanide test strips, since <strong>the</strong>y have been<br />

demonstrated to be sensitive (down to 0.02<br />

mg/L) and reliable for measuring cyanide ion<br />

concentrations in water (Battelle 2005).<br />

The most likely explanation for <strong>the</strong>se results<br />

is that organics in <strong>the</strong> digested tissue solutions<br />

containing sodium hydroxide produced <strong>the</strong><br />

anomalous readings both with <strong>the</strong> ISE and <strong>the</strong><br />

ITS test strips. Fur<strong>the</strong>r research is needed to<br />

see whe<strong>the</strong>r it is possible to measure cyanide<br />

ion concentrations in solutions obtained from<br />

marine fi sh using <strong>the</strong> Soundararajan tissue<br />

digestion method.<br />

References<br />

Battelle (2005) Industrial Test Systems, Inc. <strong>Cyanide</strong><br />

ReagentStrip TM Test Kit. Environmental<br />

Technolgy Verifi cation Report, 42 pp,<br />

under contract to U.S. Environmental<br />

Protection Agency.<br />

Frakes, T. A. and Studt, R. (1996) Evaluation<br />

<strong>of</strong> Methods for <strong>the</strong> <strong>Cyanide</strong> <strong>Detection</strong> Test for<br />

Fish Utilizing Alkaline Digestion and <strong>Cyanide</strong><br />

Specifi c Electrode. Report by Aquarium<br />

Systems associated with IMA grant from<br />

<strong>the</strong> Columbus Zoo, 8 pp, Columbus, OH.<br />

Rubec, P.J. and Soundararajan, R. (1991)<br />

Chronic toxic effects <strong>of</strong> cyanide on<br />

tropical marine fi sh. <strong>Proceedings</strong> <strong>of</strong> <strong>the</strong><br />

Seventeenth Annual Toxicity <strong>Workshop</strong>:<br />

November 5-7, 1990 (Vancouver, B.C.).<br />

Canadian Technical Report Fisheries and Aquatic<br />

Sciences 1:1774, 243-251.

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