Toxin detector

No need to use mice anymore

Published: Sunday 15 December 2002

Chemists have recently found a compound that detects a poisonous substance. The substance, called saxitoxin, is found in coastal waters. It is produced by flourishing algae. The toxin has become a menace in many countries, as it contaminates shellfish. After eating the contaminated fish, humans feel numb, dizzy and weak. At times they even die.

Managers of commercial shellfish beds in many countries monitor the presence of saxitoxin by using mice. However, this is said to be ethically contentious and too expensive for small operations or amateur fisherfolk. Roger Leblanc from Florida-based University of Miami and his colleagues, have now found an alternative: a class of molecules that recognise saxitoxin but ignore other non-toxic biochemicals found in coastal waters.

Called crown ethers, the ring-shaped molecules have fluorescent chemical groups that shine more brightly under ultraviolet light once they latch on to saxitoxin. Crown ethers easily dock on saxitoxin because they have positively charged ions similar to that of the poisonous substance.

What's more, change in the fluorescence of their chemical is detectable even at extremely low concentrations of saxitoxin.

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