Analysis of Total Nitrogen and Total Phosphorus in Environmental Water According to ASTM D8001 by Ion Chromatography　

User Benefits

- Total nitrogen (TN) and Total phosphorus(TP) in environmental water can be analyzed in accordance with ASTM D8001. - TN and TP can be measured simultaneously in a single alkaline persulfate digestion. - The use of the ICDS-40A suppressor in recycle mode is enabling environmental friendly analysis.

Introduction

In recent years, the issue of eutrophication of water quality has attracted attention. Measures against eutrophication are also included in Goal 14 of the SDGs, “Protect the Abundance of the Sea,” which has become a global issue. The major cause of eutrophication is said to be phosphorus and nitrogen, which nourish phytoplankton in water. Industrial and domestic wastewater produced by human activities contains a large amount of nitrogen and phosphorus, which are discharged into rivers, leading to eutrophication. Therefore, it is essential to control the concentration of phosphorus and nitrogen in wastewater. Ion chromatographs are widely used to analyze nitrate and phosphate ions in the environment. The sensitivity of the suppressor ion chromatograph is improved by replacing sodium ions in the eluent with hydrogen ions before detection. Figure 1 shows the flow diagram of an ion chromatograph HIC- ESP for anion analysis equipped with an electro dialyzable suppressor. In this report, we introduce examples of analysis of total nitrogen (TN) and total phosphorus (TP) in environmental water in accordance with ASTM D8001 using the anion suppressor ion chromatograph HIC-ESP. The Standard D8001 of American Society for Testing and Material (ASTM), is a test method for TN, TP and for total Kjeldahl nitrogen (TKN) by calculation in water and wastewater by ion chromatography. In Standard D8001, TN and TP can be analyzed by alkaline persulfate digestion followed by ion chromatography and TKN is determined by the calculation. TKN is calculated by subtracting the concentrations of nitrate nitrogen (NO₃-N) and nitrite nitrogen (NO₂-N) in the undigested sample from the concentration of nitrate nitrogen (NO₃-N) in the digested sample. Total Organic Carbon Analysis (TOC) is mainly used for the measurement of TN and TP. However, TOC requires digestion of TN and TP for each sample. Furthermore, it is impossible to measure phosphate ions and nitrate ions simultaneously because another molybdenum blue method is required for the digested phosphate ions. The ASTM D8001 method has the advantage of using ion chromatography to simultaneously measure TN and TP in a single sample digestion.

August 24, 2023 GMT