For nearly 20 years, scientists have longed to do more with the mass spectrometer, an instrument that detects traces of chemical elements in matter. Canadian scientists Scott Tanner and Vladimir Baranov finally achieved that goal, thanks to a little solvent and a lot of scientific elbow grease.

Since 1983, scientists have used the Inductively Coupled Plasma Mass Spectrometer (ICP-MS) to detect extremely small trace levels of chemicals in samples of gases, liquids and solids. The ICP-MS works by creating a plasma, a super-heated tiny "ball" of gas, to break apart samples of matter.

"Anything we put into that plasma, whether it's a solid or a liquid or gas, is vapourized, atomized and ionized," says Tanner, Principal Research Scientist at MDS SCIEX. The ions produced by the chemical reaction are then detected by the ICP-MS.

"The mass of the ion tells you what that atom was," Tanner explains. An ion with a mass of 88, for example, indicates the presence of the element strontium. The stronger the signal of the strontium mass, the greater the number of strontium atoms that were in the original sample.

The ICP-MS has been an invaluable tool, enabling scientists to detect probably 80 per cent of some 90 elements in the Periodic Table that are of interest or abundant enough to be found. Tanner says the spectrometer "is vastly more efficient" and powerful than conventional means of chemical analysis.

The ICP-MS works by using high-voltage radio frequency to induce an electrical charge or "spark" in argon gas flowing through a quartz tube. The spark produces electrons that are accelerated in the radio frequency field and collide at high speeds with argon atoms, creating still more electrons.

This primary chemical reaction ionizes the argon gas and creates a matter-shattering plasma that reaches temperatures of 5,000 degrees Kelvin - twice that of an oxy-acetylene flame used in welding. "It is almost like the surface of the Sun," says Baranov, Research Scientist at MDS SCIEX.

But for all its usefulness, ICP-MS technology has an "Achilles heel."

The argon gas, like every chemical put through the instrument, is ionized and recombines with other materials that are in the plasma. So if you're testing, say, a sample containing water, its hydrogen and oxygen atoms recombine with the argon to form new compounds, each with their own ions and masses. The argon also combines with itself to form another family of ions.

All this "secondary chemistry" seriously interferes with detection of some crucial ions. The argon ion, with a mass of 40, interferes directly with finding the element calcium at mass 40, for example. "I can't measure calcium because there are 'gobs and gobs' of argon ions around," Tanner says. Ions of iron, potassium, and calcium all have the same masses as unwanted ions. These ion "couplets" cause so much chemical interference, those elements are impossible to measure at the necessary levels.

"But they also happen to be very important elements in semi-conductor manufacture," Tanner notes. "Because if those elements are embedded in a semi-conductor, they degrade the performance of that semi-conductor." Arsenic in blood and urine also is impossible to analyze with the ICP-MS.

Scientists have tried, without much success, to get around the ICP-MS's limitations by increasing the instrument's resolution or using a lower-temperature plasma to reduce the chemical interference.

Tanner had been working on modifying an existing ICP-MS to give it the high-mass resolution -approximately nine orders of magnitude - required to eliminate the interference. Baranov, working toward the same goal, had been experimenting with a different type of chemical reaction chamber or cell for the mass spectrometer. Then, as the two research scientists say, "for reasons that are difficult to remember now, Vladimir's reaction cell was installed on Scott's high-resolution instrument."

Soon afterward, they noticed that a new ion had apparently formed from an exceeding low trace residue of a solvent that had been used to clean the instrument. The residue had been ionized within the reaction cell. The pair realized that if they could apply physical means to control the inherent secondary chemistry to prevent the formation of unwanted ions within the reaction cell, this would generate a stronger signal from the primary chemistry. In other words, preventing the formation of unwanted ion couplets in the reaction chamber would leave only strong signals from the ions of those elements being sought.

"We had a pretty good idea about how we should do it," Baranov recalls. "The only question was . . . can we actually get everything we need out of our instrument in combination with ion chemistry, in order to get this enormous efficiency?"

Their breakthrough came on the evening of April 16, 1997. They decided to add a direct current power supply to their reconfigured experimental instrument. Their ICP-MS now had a conventional low-resolution mass analyzer, rather than a high-resolution analyzer that scientific literature suggested as the best approach to the problem. Adding the direct current provided a "band-pass," a way to apply electric fields to suppress the secondary chemistry occurring in the instrument's reaction chamber.

"That night, when that configuration of instrument was assembled, I think there was an expectation that we would see a gain in performance," Tanner says. "But it was way beyond what I had dreamed we'd be able to do. And that was the stunning excitement."

Agrees Baranov: "Finally, we found a combination of tools which gave us very good results."

The Dynamic Reaction Cell™ employs a reaction chamber filled with a gas that reacts with one of the pair of "troublesome" ion couplets having the same mass. The reactive ion reacts to form a different ion that has a different mass, while the non-reactive ion passes unscathed through the instrument. This elegant application of ion-molecule chemistry resolves the chemical interference, leaving the normally interfered element to be detected at exceptionally trace levels. The DRC also uses electric fields to instantly adjust the band-pass, to prevent unwanted ions having the same mass as the elements being investigated from being formed and transmitted through the mass spectrometer.

"Drs. Tanner and Baranov invented and, with their team at SCIEX, brought to market an innovative instrument that has proven to solve long-standing, complex analytical problems in a simplistic fashion," says Dr. David Nixon of the world-renowned Mayo Clinic in Rochester, Minnesota.

"The pioneering work of Tanner and Baranov is having a huge impact on research in the area of analytical atomic spectrometry and elemental analysis, in addition to revolutionizing the practical capabilities of ICP-MS," says John Olesik, director of the Microscopic and Chemical Analysis Research Center at Ohio State University. Their innovation "could open entirely new applications of mass spectrometry to biomedical research," he says.

The DRC-equipped ICP-MS enables the semi-conductor industry to analyze, quickly, cheaply and precisely concentrated solutions during computer chip manufacturing. In medicine, the DRC makes it possible to detect potentially toxic elements like arsenic, thallium and chromium in blood or urine. In geology, the technology can date complex rock samples without the need for chemical pre-treatment.

"The development of the DRC furthers the deserved perception of Canadian excellence in ion chemistry and mass spectrometry," says chemistry researcher Diethard Bohme of York University.

Each year, Manning Innovation Awards presents $135,000 in prize money, distributed among four leading Canadian innovators, as well as $20,000 among eight Canada-Wide Science Fair winners. During the past two decades, the Foundation has awarded $2.75 million to encourage and recognize Canadian innovators.