Model : Büchi Speed Digester K-425 / K-436

Acid digestion for converting organic nitrogen to ammonium.

The Büchi Speed Digester K-425 / K-436 is a high-performance acid digestion system for rapid, reproducible conversion of organic nitrogen to ammonium in solid and liquid samples. It is the essential first step in total Kjeldahl nitrogen (TKN) determination.

Overview

Our center is equipped with a Büchi Speed Digester K-425 / K-436, a reliable and efficient digestion unit designed to process multiple samples simultaneously under controlled temperature programs. The system breaks down organic matter with concentrated sulfuric acid in the presence of a catalyst, converting organically bound nitrogen into ammonium sulfate.

Paired with a distillation and titration unit, this digester enables accurate TKN analysis in sludge, compost, soil, wastewater, and waste-derived materials, supporting nutrient profiling, regulatory compliance, and circular economy nutrient recovery.

What It Provide

The digestion system itself does not perform analytical measurement; it chemically converts organic nitrogen species into a single measurable form (ammonium) for subsequent quantification. Its controlled process ensures complete conversion without nitrogen loss.

  • Organic Nitrogen Digestion Converts organic nitrogen compounds to ammonium via acid decomposition and catalysis.
  • Sample Throughput Processes up to 20 samples simultaneously, depending on block configuration.
  • Reproducible Conditions Programmable temperature ramps and timer ensure consistent batch-to-batch digestion.

Key Applications

The Kjeldahl digestion system provides the critical sample preparation step for TKN analysis across environmental and waste matrices.

  • Sludge and Biosolids Analysis Digests sludge samples for organic nitrogen quantification.
  • Compost and Organic Waste Breaks down organic matter to determine nutrient nitrogen content.
  • Soil Fertility Assessment Converts soil organic nitrogen to ammonium for TKN analysis.

All devices are operated within standardized laboratory workflows to ensure accuracy, traceability, and compliance with analytical standards.