ISO 1871
Food and feed products — General guidelines for the determination of nitrogen by the Kjeldahl method.
Total nitrogen content of agricultural food and feed products, by the Kjeldahl method; nitrogen is converted to crude protein with a product-specific factor.
Agricultural food products and feeding stuffs — the general-reference Kjeldahl procedure that product-specific standards build on.
Method principle.
Kjeldahl: catalytic digestion in concentrated sulphuric acid, alkaline steam distillation into boric acid, then titration of the absorbed ammonia. Read the full Kjeldahl method note →
Laboratory workflow.
Digestion
The sample is digested in concentrated sulphuric acid with a catalyst on a digestion block (Smart, X, S or Gr series), converting organic nitrogen to ammonium.
Distillation
Alkali is added and steam distillation releases the ammonia, which is absorbed in boric acid — automated on every K-series analyzer.
Titration
The absorbed ammonia is titrated to a colorimetric end point detected by a 16-bit tri-primary color sensor (built in on K06, K12, K18 and K1306; external on K1305/K1301).
Data handling
Results are calculated, stored and exported — K12/K18 store up to 5,000,000 test results with USB, Wi-Fi and host-control output; K18 adds LIMS connectivity.
Relevant SONNEN instruments.
Run this determination on an automatic Kjeldahl analyzer — the K12 completes distillation and titration unattended, and pairs with an autosampler for 20/35-sample batches.
FAQ.
Which SONNEN analyzers list ISO 1871?
What sample sizes does the Kjeldahl workflow take?
Working to ISO 1871?
Tell us your sample type — we will map the instrument to the method.