Thermo Fisher Scientific and The American Society for Testing and Materials (ASTM) have developed an ion chromatography-based method for the simultaneous determination of nitrogen and phosphorous levels in water.

The D8001 Test Method for Determination of Total Nitrogen, Total Kjeldahl Nitrogen by Calculation, and Total Phosphorus in Water and Waste Water by Ion Chromatography enables users to concurrently monitor total nitrogen as nitrate and total phosphorus as orthophosphate in unfiltered water samples.

The new method works in a two-step process including sample digestion and analysis. In the first step, a water sample is digested with alkaline persulfate, resulting in oxidation of nitrogen compounds to nitrate and hydrolysis of phosphorus to orthophosphate.

This is followed by the sample being analyzed using an ion chromatography platform, such as the Thermo Scientific Dionex Integrion HPIC system coupled with the Thermo Scientific Chromeleon Chromatography Data System (CDS) software, to give out accurate and reproducible determination of nutrients at high throughputs.

At present, laboratories use two different methods to determine total kjeldahl nitrogen (TKN) and total phosphate.

The new test can be incorporated into existing ion chromatography protocols with the addition of a single sample digestion and analysis step to calculate total nitrogen and total phosphate simultaneously.

ASTM International Subcommittee D19.06 chairman Robert Joyce said: “Thermo Fisher’s method provides a single, reliable instrumental method for the determination of the target analytes in water, in place of traditional multiple and complex wet chemical methods, with the opportunity for accumulative errors.

“We expect the method should deliver labor savings, as well as improved sensitivity and accuracy.”

Thermo Fisher Scientific environmental and industrial marketing, chromatography and mass spectrometry senior director and ASTM member Richard Jack said: “Excess amounts of essential nutrients such as nitrogen and phosphorous can cause algal blooms, leading to the generation of toxic microcystins.

“With this new method, scientists should be able to identify excess nutrients in waterways from water treatment and agricultural runoffs.”