November 2010

A clearer result

B.C. lab offers sharper tool for environmental monitoring

By Peter Caulfield

ALS lab

ALS labratory’s highly prized high-resolution inductively coupled plasma mass spectrometer is one of a few commercially available units in North America | Photo courtesy of ALS Environmental

 ALS Environmental recently moved into its new laboratory in the Vancouver suburb of Burnaby. The new facility, which covers 41,000 square feet, is notable for having one of the very few commercial high-resolution inductively coupled plasma mass spectrometers (HR-ICPMS) in North America. Tim Crowther, regional client services manager, ALS Environmental, said there are only “one or two” in Canada and “a few” in the United States. Only in Sweden is the instrument common in environmental labs.

“The [instrument] is the most advanced technology available for analyzing trace amounts of metals and one of the first broad applications in a commercial environmental laboratory in Canada,” Crowther said. The HR-ICPMS is not another example of more powerful technology for its own sake.

“Environmental regulators are becoming more demanding, especially on mining and exploration work being done in northern Canada,” Crowther added. “They want lab tests that are accurate and that can detect baseline concentrations of metals and other contaminants in the most pristine waters in Canada, as well as tests that can check for the cumulative effect of metals over time. So we need to be able to provide the service and the results that the regulators, and our clients, ask us to provide.”

The HR-ICPMS is about the size of a sub-compact car. Manufactured by Thermo Scientific, it costs over half a million dollars. The instrument enables the lab to test for extremely low concentrations (parts per trillion) of metals such as cadmium, lead and zinc in water, fish, vegetation and blood samples, for example. It can also analyze milligram quantities of samples (e.g. from fish biopsies), which enables it to examine the cumulative effects of metals in an environment over time.

The analysis of a sample in the HR-ICPMS begins with the aspiration of a liquid into the instrument, which is then introduced into a plasma torch. The temperature of the plasma torch is approximately 6,000 degrees Celsius, or 10 times as hot as a typical pizza oven. The hot plasma breaks the sample into metal ions, which enables the lab to detect minute quantities of any metal that may be present in the sample. The more commonly used low-resolution spectrometers often cannot recognize differences in the masses of the metal ions in the sample.

“To compare the HR-ICPMS to the more common low-resolution ICPMS is like watching high-definition versusstandard-definition television,” Crowther said. “The picture resolution is far superior.”

Vancouver-based Lorax Environmental Services Ltd., an environmental consulting company, has been making use of ALS’s high-resolution mass spectrometer. Senior environmental geochemist Alan Martin said Lorax uses the instrument for analyzing surface, pore and ground waters. The high-resolution instrument is able to tackle complex contamination matrices, such as seawater or saline groundwater, without loss of sensitivity.

“For pore water analysis, we have to conduct all of our analyses on samples that are only four to six milligrams,” Martin said. “ALS has configured its instrument so that it is compatible with these volume limitations.”

Martin added that the high-resolution mass spectrometer is extremely sensitive, which enables it to detect trace elements, even if the sample has been diluted. “The high-res instrument also offers excellent spectral resolution of specific isotopes, which minimizes the potential for interference,” he said.

In addition to the HR-ICPMS, the laboratory has other instruments to deal with even the most complicated (i.e. many interferences from other elements) samples, such as atomic fluorescence spectrometers (AFS). These spectrometers detect the fluorescence of the gaseous form of metals such as arsenic, selenium, antimony and mercury to measure their concentration in a sample.

“The spectrometer for mercury is a great improvement in sensitivity over the more commonly used atomic absorption spectrometer and will allow parts-per-trillion levels of detection in waters,” Crowther said.

Another bow in the ALS environmental quiver is a collision/reaction cell ICPMS (CRC). Crowther said the CRC measures water and soil samples that have a significant concentration of metals or chemicals that can interfere with the measurement of other metals and is a significant improvement over the more common low-resolution mass spectrometer.

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