Standards · Methods · 7 references
Methods & standards.
Every Sonnen instrument is specified against a published method. This section explains the Kjeldahl workflow and the national and international standards behind each determination — including the two Chinese standards Sonnen helped draft.
The core method.
Method
The Kjeldahl method
Digestion → distillation → titration: how Kjeldahl nitrogen determination works, which samples it covers (0.1–240 mg N), and the difference between semi-automatic and fully automatic analyzers.
Read the method note →Drafted by Sonnen
GB/T 22923-2008 · JJF 109-2012
Sonnen is a co-drafter of China’s national standard for fertilizer nitrogen determination and of the Calibration Specification for Nitrogen Analyzer.
GB/T 22923-2008 → JJF 109-2012 →The standards behind the specifications.
Food and feed products — General guidelines for the determination of nitrogen by the Kjeldahl method
Open
International Organization for Standardization — listed on Sonnen K1305 / K1301.
Cereals and pulses — Determination of nitrogen content and calculation of crude protein content — Kjeldahl method
Open
International Organization for Standardization — listed on Sonnen K1305 / K1301.
Milk and milk products — Determination of nitrogen content (parts 2, 3 and 4)
Open
ISO / International Dairy Federation — listed on Sonnen K1305 / K1301.
Nitrogen in meat and meat products (reference method) — listed together with ISO 937
Open
AOAC International — listed on Sonnen K1305 / K1301.
China national standard — determination of nitrogen, phosphorus and potassium in chemical fertilizers by automatic analyzer
Open
Standardization Administration of China — listed on Sonnen K12 / K18 / K1306.
Calibration Specification for Nitrogen Analyzer
Open
China national metrology technical specification — listed on Sonnen K12 / K18 / K1306.
Working to a standard not listed here?
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