Nutrients (i.e., nitrogen and phosphorus) are a natural part of the aquatic ecosystems that help support the growth of algae and aquatic plants, which provide shelter and food for fish and other organisms.  However, excess nitrogen and phosphorus in the waters, such as from anthropogenic sources, can cause serious environmental and health issues.  Excessive nutrients in the water can create algal blooms, which can decrease the oxygen in the water that are needed by fish and other aquatic life to survive.  Some algal blooms are also harmful to humans because they produce elevated toxins and bacterial growth that can cause illnesses when coming in contact with the water, consuming tainted fish, or drinking contaminated water.  Because a national numeric criteria doesn't exist, the EPA requested that each state develop criteria for their water bodies.  Simultaneous nitrogen and phosphorus determinations are typically accomplished by Kjeldahl digestion methods.  However, this procedure suffers from several drawbacks; such as increased safety risks, increased cost to dispose of mercury, and by providing values for organic nitrogen and ammonium only (excludes inorganic nitrite and nitrate).  Alkaline persulfate digestion for simultaneous total nitrogen and phosphorus determinations is a more sensitive, accurate, and less toxic alternative to Kjeldahl digestion.  In this report, alkaline persulfate digestion was used to convert nitrogen to nitrate and phosphorus to phosphate followed by determination using anion exchange chromatography with suppressed conductivity detection.  To initially evaluate the method, several inorganic and organic nitrogen and phosphorus-containing compounds were digested and the recoveries were determined.  For the nitrogen-containing compounds the recoveries ranged from 93-100% and from 85-99% for the phosphorus-containing compounds.  The linearity, sensitivity, and recovery of nitrate-N and phosphate-P in environmental waters will be discussed.

Determination of total nitrogen and phosphorus in environmental waters by using alkaline persulfate digestion and ion chromatography with suppressed conductivity detection

247th National Meeting (2014)

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