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Tech Intelligence AL AL allow the analysis of many kinds of samples by Mike May


Humans and nature can pollute the environment, and our health often depends on tracking and analyzing the toxic compounds. “Certain toxins and pollutants are naturally made in the oceans,” says Vinayak Agarwal, Helen Hay Whitney Foundation Postdoctoral Scholar at the University of California at San Diego’s Scripps Institution of Oceanography, “and they resemble some of the most toxic molecules that humans have ever syn- thesized.” Humans can stop making toxic compounds, but what can we do when nature makes them?


The source of a dangerous compound determines how it can be avoided, if at all. “If [it’s] naturally made, you can’t do anything unless you know where the exposure is coming from,” Agarwal says. “So if a fish causes mercury poisoning, you need to not eat that.”


To find such toxic compounds, Agarwal says, “MS is a fundamental tool.” He adds, “This work depends critically on liquid or gas chromatography plus MS.” With LC/MS, a quadrupole time of flight (QTOF) MS works well and is relatively inexpensive, according to Agarwal. “For brominated samples, electron capture negative ion MS gives good ionization.” Single, tandem and triple quadrupole MS can be used with GC. So the right MS depends on the problem.


Tailoring the tool “Depending on the configuration, MS provides a broad-reaching


technique for answering environmental questions,” says Craig Marvin, global environmental industry manager for Agilent Technologies (Santa Clara, Calif.).


Some compounds work best with LC, some with GC, and others with both techniques. “Things amenable to analysis by GC/MS, like volatiles, are not good candidates for analysis by LC/MS,” Marvin says. Composition of the sample also determines the best MS to use. “Triple quadrupole MS systems, like the Agilent 6470 Triple Quadrupole LC/MS System, eliminate chemical interference, which provides additional selectivity and can bet- ter identify the targeted compounds in complex matrices,” says Marvin.


“QTOF is used for nontargeted screening—identifying things you don’t know are in the sample—critically important for monitoring emerg- ing contaminants. The Agilent 7010 Triple Quadrupole GC/MS System


AMERICAN LABORATORY 36


The Agilent 7010 Triple Quadrupole GC/MS System gets more of the sample to the detector to increase its sensitivity. (Image courtesy of Agilent Technologies.)


produces more ions for a given injected concentration and draws a higher percentage of those ions to the detector, providing environmen- tal scientists with a very valuable tool for [detecting] trace chemicals in complex environmental matrices.” Marvin explains. “This system provides an order-of-magnitude improvement in sensitivity compared to conventional MS/MS systems—allowing analysts to meet detection- limit requirements using reduced volume of sample and organic solvent in the sample processing.”


In some cases, scientists want to test environmental samples with little preparation, and this can be done with an MS system that


MARCH 2016


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Environmental Mass Spectrometry Multiple upstream devices and various forms of detection


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