Proceedings of the International Cyanide Detection Testing Workshop

The Cyantesmo paper changes color from
light green to dark blue depending on the
concentration of hydrogen cyanide liberated.
Several papers have been published using
Cyantesmo paper. Flinger et al. (1992) used
it as a screening tool to detect the presence
of cyanide liberated from blood samples.
Relia et al. (2004) evaluated the method
with concentrations of cyanide ion ranging
from 0.25 to 30 mg/L (ppm). The test strips
demonstrated incrementally increasing deep
blue color changes over a progressively longer
portion of the test strip in less than fi ve minutes
for each concentration of cyanide including
1, 3, 10, and 30 mg/L. The concentrations of
0.25, 0.5, and 0.75 mg/L required more than
two hours to begin demonstration of a color
change.
It is recommended that the FDA protocol be
evaluated as a screening tool for the detection
of cyanide in fi sh tissue samples near the
point of collection in exporting countries.
The procedure will require the use of regional
testing laboratories. It has the advantage that
many samples can be analyzed at low cost.
BioSensors
Mak et al. (2005a) presented a summary of
various papers that have developed biosensors
for detecting cyanide ion. Most of the methods
are dependent on measuring chemical reaction
products based on enzymatic reactions (e.g.,
formate production from action of cyanide
hydratase, cytochrome oxidase inhibition,
peroxidase inhibition, rhodanese and sulphite
oxidase reactions). There is also a microbial
sensor, and the measurement of oxygen
uptake by bacteria. There are efforts being
made to link the enzymatic reactions to
potentiometers to measure the enzymatic
reaction as changes in electrical potentials.
The idea is to create a microprobe (containing
the enzymes) that would be inserted into the
blood to give a reading based on a change in
Figure 1. Sealed test tubes used by the U.S. Food and Drug Administration to detect the presence of cyanide
in foodstuffs using Cyantesmo paper suspended above an acidifi ed sample. Image provided by Dr. Fred Fricke,
USFDA.
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