Proceedings of the International Cyanide Detection Testing Workshop

and Marine Parks within the Indonesian
Ministry of Marine Affairs and Fisheries)
both expressed, in their presentations at the
Cyanide Detection Workshop, the need for
a rapid, easy to use fi eld test to support law
enforcement efforts. The available kits and/
or meters generally measure CN - in solution.
These kits may be useful to detect cyanide ion
in solution (such as in seized cyanide squirt
bottles) or to detect cyanide after suspected
tablets seized from collectors/fi shers are
dissolved in water (fresh or saltwater). The
fi shers/collectors use either sodium cyanide
(NaCN) or potassium cyanide (KCN) for
cyanide fi shing. Sodium cyanide is mostly used
to capture fi sh by fi shers in the Philippines;
while potassium cyanide is more commonly
employed for cyanide fi shing in Indonesia.
The committee agreed that portable test kits
designed for measuring cyanide in solution are
unlikely to be effective in detecting cyanide
bound in the tissues of MAF.
Soudararajan Procedure
Another suggested method for testing fi sh
samples for the presence of cyanide was
developed by Dr. Rengarajan Soundararajan
in 1990 (Rubec and Soundararajan 1991). The
method involves the extraction of cyanide
from blended fi sh tissues using concentrated
sodium hydroxide (NaOH). The method is
appealing since it is relatively simple and quick
to conduct. The cyanide ion is released from
the tissues into sodium hydroxide (NaOH).
The high pH (pH 12-13) of the solution
prevents the cyanide from being lost to the
atmosphere. Cyanide concentrations can then
be measured with an ion-selective electrode
(ISE).
Five fi sh species obtained from Indonesia tested
in the U.S.A. had cyanide ion concentrations
ranging from 5.8 to 23 mg/kg (ppm) (Rubec
and Soundararajan 1991). A Clown Triggerfi sh
obtained from the Philippines exhibited a
46
cyanide ion measurement of 1120 mg/kg. No
cyanide was detected in two Flame Angelfi sh
obtained from the Marshall Islands, for two
French Angelfi sh from the Caribbean, and
two species of surgeonfi sh obtained from
Hawaii. Hence, cyanide was detected in fi sh
from countries known to have collectors
using cyanide and no cyanide was detected in
fi sh obtained from countries where cyanide is
not used for collecting marine aquarium fi sh.
The International Marinelife Alliance (IMA)
evaluated the technique in 1991, but abandoned
it after it was found to give anomalously high
cyanide readings. It was suspected that the
anomalously high readings found by the IMA
might have occurred because of false-positive
readings caused by sulfi de interference with
the ISE electrode.
Research by Aquarium Systems was conducted
with a small grant obtained by IMA from the
Columbus Zoo (Frakes and Studt 1996). The
basic procedure was to expose the fi sh to
known concentration of cyanide ion, kill the
fi sh, then puree the samples in 5 Molar (M)
NaOH. The NaOH volume was calculated
to yield a 10% by weight fi sh slurry. This
slurry was allowed to settle and a clear aliquot
was diluted with distilled water to produce
another 10% by weight dilution. Cyanide ion
(CN - ) concentrations in the fi nal solution, 1%
fi sh tissue, and approximately 0.5M-NaOH
were measured in millivolts (mV) recorded
with an Orion CN - ISE linked to an Orion
ISE meter.
These readings were compared with a semilog
plot (calibration) produced with known
cyanide concentrations of 0.1, 1.0, and 10
mg/L levels with mV readings recorded
as each level (Frakes and Studt 1996). Lead
carbonate was added to the supernatant
solution to precipitate sulfi des from solution.
The fi rst trial compared readings with Atlantic