An innovative method for determining the level of pollutants

Polycyclic aromatic hydrocarbons (PAH) are organic compounds that can be a serious pollutant. Now there is a new method to measure their concentration

Polycyclic aromatic hydrocarbons (PAH) are organic compounds that can be a serious pollutant. They are found, among other things, in soils where chemical industries are located and in water contaminated by ship fuels. Chemists from the University of Valencia in Spain offer simple methods for examining the effect of these substances on several mediums using microextraction.

The innovative method is a filtering method: these analyzes provide a quick reaction (positive/negative) without the use of destructive tools, solvents and extended time. The innovative method includes a needle inserted into the top of the container where the sample is stored. This needle contains a fiber that absorbs the vapors of the substance that are in the upper cavity of the container. This space, located between the sample and the lid, can only contribute information for volatile compounds such as polycyclic aromatic hydrocarbons.

The extraction procedure from the upper space of the container allows the preservation of the fiber under optimal conditions. If the fiber is inserted directly into the sample, it may be damaged due to the large amount of molecules, however, using the microextraction of the vapors, a method known as HS-SPME (headspace solid phase microextraction), the interference of large and non-volatile molecules is avoided.

In the next step, the gases adsorbed in the fiber must be separated and characterized. The researchers did this using gas chromatography, which can be used to separate the components at temperatures below 400-350 degrees Celsius. In the end, the components can be characterized and quantified using a suitable detector.

The researchers developed methods by which it was possible to determine, simultaneously, a number of polycyclic aromatic hydrocarbons of low and medium molecular weight, according to the variety of conditions and measurement mediums (water, sand, sediments, etc.). They used their new method to detect polycyclic aromatic hydrocarbons in water sources near chemical industries, and indeed discovered them in these sources.

The news about the study