Proceedings of the International Cyanide Detection Testing Workshop

in the Philippines under contract with BFAR
from 1993 to 2001. The ISE method, utilized
by the IMA has been criticized by several
groups that attempted to repeat the CDT
procedures used by IMA (Holthus 1999, Mak
2003, Mak et al. 2005b). This led some people
to question whether the ISE method utilized
by IMA and presently by BFAR chemists is
reliable.
In 1999, the Marine Aquarium Council
(MAC) convened a panel of eight scientists to
review the SOP manual utilized by the IMA
(Manipula et al. 1995). The SOP is essentially
the ASTM ISE method discussed above.
The panel members noted that the SOP did
not contain quality assurance-quality control
(QA/QC) procedures (Holthus 1999). The
IMA submitted a formal response to this
report (IMA-Philippines 1999). The IMA
noted that QA/QC procedures were being
routinely applied by the six BFAR/IMA
laboratories and agreed to incorporate them
into a revised SOP. This was done and four
new SOP manuals were produced (Alban et al.
2001, Manipula et al. 2001a, 2001b, 2001c).
The main disagreement by IMA (IMA-
Philippines 1999) with the MAC report
(Holthus 1999) pertains to analyses conducted
by an unspecifi ed chemist contracted by MAC
to repeat the ISE method. The consultant
changed the test apparatus (substituted a 50
ml mini-distillation fl ask) and made other
changes to the procedure. The main criticism
by IMA was that the consultant overheated
the distillation fl ask and infused air into the
refl ux condenser at too high a rate resulting in
low percent recoveries of cyanide ion in fi ve
experiments involving marine aquarium fi sh.
Tables 2, 3, 4, and 5 indicate percent recoveries
of cyanide ion ranging from 31-77% (Holthus
1999). If the ASTM (1997) procedure was
correctly conducted one should expect
recoveries of CN - near 100%. The published
51
procedure states “Equivalent apparatus is
acceptable provided cyanide recoveries of
100 “ 4% are documented” (ASTM 1997).
Hence, the low percent recoveries of CN -
after the digestion and distillation of cyanide
spiked tissue samples reported (Holthus 1999)
brings into serious question the validity of
the consultant’s experimental results (IMA-
Philippines 1999). The IMA noted that it
routinely had percent recoveries of cyanide
greater than 90%. Hence, the low percent
recoveries experienced by the consultant
were not a problem for IMA chemists who
correctly applied the ISE methods described
in the SOP.
The other main concern (IMA-Philippines
1999) was that the consultant claimed the
levels of cyanide measured with the ISE
were below detectable limits (BDL) (Holthus
1999). In three experiments (Tables 3, 4
and 5) cyanide levels recovered from spiked
samples ranged from 0.0001 to 0.0005 mg/g.
The consultant claimed that the ISE method
was invalid because the test results were BDL.
The IMA pointed out that the consultant was
wrong because the concentrations should have
been reported in parts per million wet weight,
which is expressed as mg/kg. The results
ranged from 0.1 to 0.5 mg/kg (ppm). Hence,
the consultant’s results were well within the
range of detection by the ISE apparatus and
were not below detectable limits.
The MAC also contracted Dr. Reinhard
Renneberg at the Hong Kong University of
Science and Technology to review cyanide
detection methods and develop a new cyanide
detection method. A graduate student in his
laboratory, Karen Mak attempted to repeat
the ISE method previously used by the IMA
(Mak 2003). Unfortunately, the manual she
followed was not the correct SOP manual
utilized by the BFAR/IMA laboratories
(Manipula 1995). She used a handout (IMA-