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6593151 
Journal Article 
DETERMINATION OF TOTAL NITROGEN IN FOOD, ENVIRONMENTAL AND OTHER SAMPLES BY ION CHROMATOGRAPHY AFTER KJELDAHL DIGESTION 
Jackson, PE; Krol, J; Heckenberg, AL; Mientjes, M; Staal, WIM; , 
1991 
Yes 
Journal of Chromatography A
ISSN: 0021-9673
EISSN: 1873-3778 
ELSEVIER SCIENCE BV 
AMSTERDAM 
546 
C 
405-410 
English 
WOS:A1991FV82900039 
Total nitrogen in food, environmental and many other matrices is usually determined by Kjeldahl digestion-distillation followed by titration. The use of ion chromatography to determine total nitrogen as ammonium ion after sample digestion significantly improves the speed of the analysis compared with the conventional method. A poly(styrene-divinylbenzene) cation-exchange column with dilute nitric acid as eluent and indirect conductivity detection was used for the ion chromatographic determination of ammonium in the presence of the elevated levels of sulfuric acid found in the digested sample. The peak-area precision for ten replicate injections of an ammonium standard was 0.6% [relative standard deviation (R.S.D.)] and the retention time precision was 0.3% (R.S.D.). The determination of ammonium was linear from 15 ppb (10(9)) up to 25 ppm. The results obtained by the ion chromatographic method were compared with those for the conventional distillation and titration approach for the determination of total nitrogen in animal feeds. The application of the ion chromatographic method is also demonstrated for a variety of other sample matrices. 
1990 INTERNATIONAL ION CHROMATOGRAPHY SYMP 
SAN DIEGO, CA