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Flow-injection determination of ammonia in kjeldahl digests by gas diffusion and conductometry

✍ Scribed by Celio Pasquini; Lourival Cardoso de Faria

Publisher
Elsevier Science
Year
1987
Tongue
English
Weight
580 KB
Volume
193
Category
Article
ISSN
0003-2670

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✦ Synopsis

A flow injection/conductometric method is proposed for determing ammonia in solutions obtained from Kjeldahl digestion. The method is based on diffusion of ammonia through a PTFE membrane from an alkaline (NaOH/EDTA) medium to a deionized water stream. The change in conductance of the deionized water stream is proportional to the ammonia concentration present in the digest. The effects of flow parameters, temperature and potential interferences are reported. Approximately 100 samples can be injected per hour; the precision is about 1%. Results for total nitrogen in vegetable tissues, animal feeds and fertilizers are in good agreement with those obtained by the usual distillation/titration method.

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