DESPERATELY SEEKING CHARLIE

Is That Smudge Of White Powder As Innocent As It Seems?

A POCKET-SIZED detector that can instantly spot traces of illicit
drugs could be on the way. It would make life tougher for drug dealers
by letting police confirm immediately which drugs, if any, a person
has handled.

At the moment, drugs and forensic evidence from drug busts have to be
sent to approved labs for analysis if the results are to stand up in
court. For rough, on-site testing, police use sniffer dogs and "ion
scans". Ion scanners are around the size of a small fridge, says Chris
Lennard from the Australian Federal Police forensic laboratory in
Canberra. Drug samples are put in a cell in the ion scanner and
vaporised. The time it takes for the particles to drift from one end
of a cell to the other identifies the drug, he says.

Simon Lewis and colleagues at Deakin University in Geelong near
Melbourne set out to create a pocket-sized drug detector for people
with no lab training. "Suppose I've got an empty bag here and I want
to know, did it ever contain drugs?" says Lewis. You just take a swab
from the bag and mix it with deionised water in a vial. You then fill
a second vial with a solution of a metal complex that varies according
to the drug you suspect might be there.

The two vials are slotted into holes in Lewis's detector where the
liquids from each vial are mixed in precise quantities. As they mix, a
reaction between the drug and metal complex produces a brief flash of
light. A light sensor identifies the drug by measuring the intensity,
wavelength and duration of the flash, says Deakin.

In a test, Lewis used a compound called ruthenium metal complex to
look for the common analgesic drug codeine. He found he could detect 6
micrograms of the drug in a litre. "It's like being able to taste a
crushed Tic Tac in an Olympic-sized swimming pool," he says.

By choosing specific metal complexes that react with different drugs
to produce light, the system could quickly distinguish between hard
drugs like cocaine and more innocuous substances, says Lewis.

Zoran Skopec, director of the Australian Forensic Drug Laboratory in
Sydney, is interested in Lewis's device but wonders how well it would
fare if there was a mixture of drugs. "Field kits like this might work
with we I I-establi shed chemicals," he says. "But new drugs or
particular mixes often give a number of confusing answers."

Lewis agrees that mixtures can be difficult to identify. "That's what
we're working towards," he says.