Kjeldahl method with ninhydrin finish low levels

This determination of particulate nitrogen by reaction with ninhydrin is a modification of the previous method using Nessler s reagent with a more sensitive coloometric technique based on a method by S. Jacobs (Analyst, 87 53, 1962). The method enables the particulate nitrogen content of deep ocean samples to be determined using 1 liter or less of sample. Details have recently been published by Holm-Hansen (Limnol. Oceanog. 13 175,1968). 

PRECISION AT THE 6.0 fUG LEVEL The correct value lies in the range  

The nitrogen in the particulate matter is converted to ammonia by a Kjeldahl treatment with sulphuric acid. The resulting ammonia is determined absorptio-metrically by complex formation with ninhydrin-hydrindantin, without prior distillation. 

An ice or cold-water bath fitted with a rack to hold the above tubes. 

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IV.6.II. KJELDAHL METHOD WITH NINHYDRIN FINISH (LOW LEVELS)... 

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