Water Samples Yield Their Secrets

Because polluted water can contain a wide range of chemicals and concentrations, a sensitive approach is necessary. Researchers have now developed an automated way to identify and quantify even trace levels of organic pollutants in wastewater and rivers (Anal. Chem., DOI: 10.1021/ac102909g).

To catch pollutants at trace levels, environmental chemist María José Góméz at The Madrid Institute of Advanced Studies in Water Technologies and her team began with a simple concentration step with a polymer-coated stir bar. They spun the stir bar in a heated water sample overnight. To encourage pollutants to absorb into the polymer, the investigators added methanol and table salt to the sample.

The next day, the investigators heated the polymer to release the pollutants. They separated these compounds using two rounds of gas chromatography and then identified and measured them with mass spectrometry. The method could detect most compounds in the sample, which included pesticides and polycyclic aromatic hydrocarbons, at concentrations below1 ng/L, a detection level that was similar to or better than other available methods.

The team tested their method on Spain's Henares River, which receives effluent from a wastewater treatment plant. They compared samples to each other to see how the pollutants from the effluents changed over time and space. The investigators discovered that personal care products such as fragrances were the most abundant and persistent contaminants in the river.

Detection of low-level water pollutants is a persistent issue, comments environmental chemist Damià Barceló at the Institute of Environmental Assessment and Water Research, in Barcelona. He says the concentration step is an innovative way to tackle the problem.

This article was updated on Mar. 15, 2011, to emphasize that the technique works for nonpolar and semipolar organic pollutants.