Agilent Technologies detects PAHs in water using retention time locking and solid-phase extraction
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PALO ALTO, Calif., Aug. 16, 2002 - Agilent Technologies Inc., today announced a significant gas chromatography/mass spectroscopy (GC/MS) application that demonstrates the usefulness of retention time locking (RTL) in determining the presence of polycyclic aromatic hydrocarbons (PAHs) in water.
These hydrocarbons, widespread in the environment, are known carcinogens, mutagens and teratogens. Environmental agencies worldwide regulate and monitor the presence of aqueous PAHs. The U.S. Environmental Protection Agency, for example, lists 16 PAHs as "priority pollutants."
Agilent chemists used RTL with a DB-5ms column to characterize 35 native and 27 surrogate PAHs in under 18 minutes. Resolution was good for several critical pairs encountered in PAH analysis. Retention time locking enables any operator to reproduce identical, absolute PAH compound retention times, allowing direct comparison of results from different laboratories, regardless of operator or instrument.
To isolate and concentrate trace PAHs from water, the Agilent chemists used Agilent AccuBONDII octadecyl solid-phase extraction cartridges in spike and recovery experiments on the U.S. EPA PAH priority pollutants. At concentrations of 50 ppt, PAHs were determined with an average accuracy and reproducibility of 5 percent. A one-liter water sample was processed in less than 50 minutes with overall recoveries exceeding 70 percent even for naphthalene, a difficult analyte to isolate.
The method also included concentration and solvent-exchange steps, transferring the elution solvent dichloromethane to isooctane (a superior keeper), via a tube heater. Tube heaters provided rapid and inexpensive parallel processing of multiple samples. Unlike nitrogen blowdown, which evaporates solvent in a laboratory hood, tube heaters offer the possibility of recovering volatilized dichloromethane solvent.