Kjeldahl nitrogen by ion chromatography
The ASTM recently published method D8001 describing the determination of total nitrogen, total Kjeldahl nitrogen, and total phosphorous. The new method applies persulfate digestion with subsequent determination of Kjeldahl nitrogen by ion chromatography; no prior distillation of the matrix is required.
Total Kjeldahl and total nitrogen are commonly determined by titration after distillation of the digestion mixture to release the ammonia. The new ASTM D8001 offers an alternative applying persulfate digestion followed by ion chromatographic separation and conductivity detection with sequential suppression. The new method is described by Metrohm Application Note S-358 which can be downloaded free of charge.