Agilent Technique Analyzes Off-flavors in Drinking Water
Agilent Technologies announced an analytical technique to characterize odorous compounds in drinking water at subnanogram-per-liter levels (down to 0.1 ng/L). This new approach can help water companies control taste and odor problems in their water supplies and has been successfully used to identify a variety of off-flavor problems in drinking water systems near Paris.
This new technique combines Agilent gas chromatography/mass spectrometry (GC/MS) with Stir Bar Sorptive Extraction (SBSE) from Agilent’s German partner, GERSTEL GmbH & Co. KG. SBSE is based on sorption rather than adsorption, and is a highly sensitive, simple and fast alternative to traditional extraction methods.
To validate this approach, chemists from Anjou Recherche in Saint-Maurice, France analyzed water samples spiked with six odorous organic compounds: 2-methylisoborneol (MIB); geosmin; 2,4,6-trichloroanisole; 2,3,6-trichloroanisole; 2,3,4-trichloroanisole; and 2,4,6-tribromoanisole. The combination of GC/MS and SBSE enabled quantification of these compounds at the subnanogram per liter level, under or near their odor thresholds. Using this method, the chemists were able to extract and analyze more than 20 samples a day.
The scientists also applied this method to real-world samples taken from three different locations around Paris: the outlet of a treatment plant, a water tank and at consumer homes. The approach showed a strong correlation between flavor profile analysis, MS analysis and olfactometric detection. In addition to the target compounds, it was possible to identify unknown odorous compounds at very low levels much more rapidly than possible using conventional techniques.
Complaints received by water companies are most often due to bad tastes and odors in drinking water, particularly from the presence of chlorine and earthy or musty smelling compounds. Identifying these compounds in water has been an analytical challenge because they can cause odor even at extremely low concentrations — a problem for conventional analytical methods such as closed-loop stripping analysis, purge and trap, and solid phase micro-extraction.