Examination of Firearms Review: 2007 to 2010 - Interpol

successful identification of ricin. 26 However, the major downfall of
immunoassay technologies is that they are currently limited to one or a few
targets in each test.
A recent study has evaluated 3 cost-effective biological screening tools
capable of non-specifically determining the presence of a biological material,
such as ricin or anthrax, in a suspicious powder. 27 Evaluation of the Guardian
Bio-Threat alert (BTA) system has shown that it was capable of detecting
several toxins, such as staphylococcal enterotoxin B (SEB), botulinum toxins
(BTX) A and B, and ricin with no interference from white-powdered materials
or coloured matrices; although temperature and toxin sub-types proved
important factors to take into account. 28,29
Genetic techniques like the polymerase chain reaction (PCR) and microarrays
provide the high sensitivity required for the detection of biological agents in
the field and those samples submitted to the laboratory. To date, real time
PCR (RT-PCR) technology has shown the greatest application for the genetic
detection and identification of biological agents. 30 One of the major
disadvantages of RT-PCR is the inability to multiplex numerous simultaneous
targets.
Another technology is based on microarrays, consisting of a bank of nucleic
acid probes bound to the surface of a glass slide. The advantage of
microarrays is that the technology allows the simultaneous analyses of
hundreds to thousands of targets, but traditional microarray technology is
lengthy, complex, and technically difficult. The integration of automation and
software processing has largely removed human involvement into many of the
repetitive tasks involved in the processing and interpretation of microarrays.
Recent work on the combination of nucleic acid amplification, lateral flow
chromatography and microarray technologies provides a novel platform from
which microarrays can be developed for field deployment. 31
Other methods are also appearing, such as biosensors based on the surface
plasmon resonance technique, where the surfaces were prepared with
antibody fragments specific for the biological toxin ricin. 32,33
Stand-off detection has also attracted some attention as it does not require
contact with the agent. The detection and discrimination of the biological
warfare agent surrogate Bacillus subtilis (BG) at a distance of 20 m was
achieved using standoff laser-induced breakdown spectroscopy (ST-LIBS)
and linear correlation. 34
A covert biological attack is likely to be detected by medical practitioners in
the first instance, but there is a high likelihood that the diseases arising from a
biological agent may be misdiagnosed due to their rarity. For example,
531