The Sweet Smell of River Contamination – Investigating Sweeteners in Rivers Using Chromatography

Artificial sweeteners have not generally been considered traditional contaminants of our rivers and waterways. Although they are created through industry and factories, this is not their only outlet into the environment. Indeed, individual consumer ingestion and secretion, as well as on a more widespread scale in a commercial setting, leads to the distribution of such contaminants.

However, in recent years, the dangers posed by the growing levels of artificial sweeteners in our rivers has caused concern in scientific circles. This is chiefly because the sweeteners often retain chemical and biological stability, meaning they are not broken down or fully removed by either our digestive systems or wastewater treatment facilities.

As such, they are making their way into our bodies of water in unprecedented levels. The effect that these contaminants have on flora and fauna in the locale is as yet unknown; further investigation is needed.

The Guilty Parties

Many sweeteners are entirely unaffected by the digestive process, including saccharin and acesulfame. This is due to their swift absorption by the body, meaning they leave our systems in an unchanged format. Others, such as cyclamate and stevioside are affected to a larger degree, but still exit the body via urination with metabolites intact.

Last year, scientists began looking into the Development of a Method to Better Quantify Levels of the Persistent Organic Pollutants Iodinated X-Ray Contrast Media and Artificial Sweeteners Found in Water. Following on from that research, scientists in Spain conducted an extensive study into how best to go about identifying these sweeteners in Spanish rivers and waterways, using various high performance liquid chromatography (HPLC) and liquid chromatography in conjunction with mass spectrometry (LC-MS).

The Catalan University of Tarragona investigated the amount of contamination in nearby rivers, as well as analysing the influent and effluent samples of two wastewater treatment plants. After comparing six different HPLC columns, they finally settled upon one which offered better LC-MS performance.

The technique revealed the presence of eight different offending sweeteners. These were:

• Acesulfame
• Aspartame
• Cyclamate
• Glycyrrhizic acid
• Neohesperidin dihydrochalcone
• Saccharin
• Stevioside
• Sucralose

The research revealed illuminating information about the influents and effluents of the wastewater plant. Six of the sweeteners found in the river body as a whole were present in the influent samples, with sucralose and acesulfame the most copious. These had levels of 12-60µg/L and 49-149µg/L, respectively.

All six contaminants were found in the effluent samples too, to lesser extents. The acesulfame had dropped by 33%, while the sucralose was 40% less abundant. Other substances were more or less affected, but none were removed entirely. However, it should be stressed that the samples were taken at the same time, so this is not a fair reflection on how the treatment plant coped with one particular batch of water and its contaminants.

The State of our Rivers

These studies are among the first to successfully quantify the levels of artificial sweeteners in our rivers and waterways. Now, it is necessary to investigate what effect these are having on the plant and animal life which calls the region home, and how to take steps to curb levels of contamination, if need be.

However, this is not the first time chromatography has been used to shed a light on the state of our rivers. In March, a Taiwanese study revealed the levels of narcotic pollution of local water supplies immediately after a music festival in the area. Clearly, chromatography is a valuable tool in the fight to clear up our waterways.