Kjeldahls

The BUCHI Dist Line is a family of steam distillation instruments engineered for reliable, reproducible separation of volatile analytes from complex matrices. Built around a robust steam generator with adjustable output and integrated safety monitoring, the Dist Line delivers accurate results across food, environmental, beverage and chemical laboratories. Three configurations — EasyDist, BasicDist and MultiDist — let laboratories match automation and throughput to their workload, from occasional manual runs to fully automated sequences with integrated titration.

Key specifications:

• Adjustable steam power: 10–100 %, with programmable steam ramps for method flexibility

• MaxAccuracy mode with integrated voltage stabilizer for reproducible steam delivery

• AutoDist function for automated, reproducible start of distillation

• Optional integrated titration for direct quantification after distillation

• Intelligent cooling water flow control that minimizes water consumption

• Sensor-based safety monitoring with automatic shutdown on shield opening

• Compatible with 100, 300 and 500 mL BUCHI sample tubes

Available models:

• EasyDist — entry-level manual steam distillation

• BasicDist — semi-automated distillation with programmable methods

• MultiDist — fully automated distillation with reagent addition and titration

Applications:

• Nitrogen and protein determination (TKN, TVBN) in food, feed and fertilizers

• Alcohol, essential oils and volatile acids in beverages and wine

• Sulfite (SO2), cyanide, phenol and formaldehyde determination

• Nitrite and nitrate analysis in water, soil and wastewater

• VDK (vicinal diketones) analysis in beer and dairy

The BUCHI Kjel Line is a comprehensive series of Kjeldahl distillation instruments dedicated to fast, precise nitrogen and protein determination according to the reference Kjeldahl method. Combining a powerful steam generator, temperature-compensated distillation and optional automated titration, the Kjel Line delivers high recovery, safe operation and full traceability. Three model tiers — EasyKjel, BasicKjel and MultiKjel — cover requirements from routine QC laboratories to demanding food, environmental and feed testing facilities.

Key specifications:

• Reference Kjeldahl distillation method for nitrogen and protein determination

• Adjustable steam power: 10–100 % with programmable steam ramps

• AutoDist function — temperature-compensated automatic distillation start

• Automatic endpoint recognition for distillation

• Optional integrated titration (colorimetric or potentiometric)

• Compatible with 100, 300 and 500 mL BUCHI sample tubes

• Determines Total Kjeldahl Nitrogen (TKN), Total Volatile Basic Nitrogen (TVBN), nitrate and nitrite

Available models:

• EasyKjel — entry-level manual Kjeldahl distillation unit

• BasicKjel — semi-automated distillation with programmable methods and reagent dosing

• MultiKjel — fully automated distillation with integrated titration and data management

Applications:

• Protein content in dairy, meat, cereals, flour and beverages

• TKN measurements in water, wastewater and soil for environmental monitoring

• Nitrogen content in fertilizers and agrochemicals

• TVBN determination for fish, seafood and meat freshness assessment

• Feed quality and raw material control in agriculture

The KjelMaster K-375 combined with the KjelSampler K-376 or K-377 forms a fully automated Kjeldahl analysis platform for the highest sample throughput and walk-away operation. The system integrates distillation, colorimetric or potentiometric titration, reagent addition and data management in a single workflow, delivering excellent recovery and reproducibility for nitrogen and protein determination across food, feed, environmental and chemical laboratories.

Key specifications:

• Measuring range: 0.02–220 mg N per sample

• Recovery: >99.5 % (1–200 mg N)

• Titration methods: potentiometric and colorimetric

• Adjustable steam power: 30–100 %

• IntelliDist smart distillation with automatic temperature detection

• Compatible with all BUCHI sample tubes (100, 300 and 500 mL)

• Optional connection to barcode readers, balances and LIMS systems

Available models:

• KjelMaster K-375 — standalone fully automated distillation and titration unit

• K-375 with KjelSampler K-376 — 24 sample positions for unattended batch analysis

• K-375 with KjelSampler K-377 — 48 sample positions with dual independent racks for continuous processing

Applications:

• High-throughput protein determination in dairy, meat, grains and flour

• TKN analysis in wastewater, surface water and soils

• Nitrogen content in fertilizers and industrial chemicals

• TVBN analysis for fish and seafood freshness monitoring

• Feed and raw material quality control

BUCHI SpeedDigester and KjelDigester units together with the Scrubber K-415 form a complete digestion workstation for Kjeldahl and related sample preparation methods. Fast, reproducible sample mineralization is paired with a four-stage scrubber that neutralizes acidic fumes and captures aerosols, enabling safe operation with minimum fume-hood dependence. Modular design lets laboratories scale digestion capacity and combine multiple digesters with a single scrubber for cost-effective throughput.

Key specifications:

• SpeedDigester series (K-425, K-436, K-439) delivers fast reproducible Kjeldahl digestion

• Scrubber K-415 with four-stage neutralization: condensation, adsorption, reaction, neutralization

• 3 L neutralization capacity with visual color indicator for solution status

• Adjustable system suction: 50–400 mbar

• Pump suction rate: 32 L/min

• Activated charcoal adsorption stage for volatile organics

• Optional ECO cooling water valve; upgradeable to QuadScrubECO configuration

Available models:

• SpeedDigester K-425 — infrared-heated digestion unit for medium throughput

• SpeedDigester K-436 — 6-position infrared digester with quick heat-up

• SpeedDigester K-439 — 12-position infrared digester for high throughput

• Scrubber K-415 — fume neutralization for KjelDigester and SpeedDigester models

Applications:

• Kjeldahl digestion for protein and nitrogen determination in food and feed

• Sample preparation for environmental TKN analysis in water and soil

• Digestion of fertilizers and agrochemicals

• Safe handling of acid fumes without a dedicated fume hood

• Chemical and pharmaceutical sample preparation

The BUCHI KjelDigester K-446 and K-449 are block digestion systems built for fast, safe and reproducible sample preparation prior to Kjeldahl nitrogen determination. Up to 20 samples are digested in parallel, delivering throughput of up to 120 samples per working day. Improved thermal homogeneity, an accelerated heating and cooling cycle and an enhanced sealing system reduce total analysis time by up to two hours while keeping fume management safe and clean. Both units integrate seamlessly with KjelSampler K-376/K-377 autosamplers for fully automated Kjeldahl workflows.

Key specifications:

• Sample positions: 20

• Temperature control range: 30 - 450 °C

• Maximum temperature: 450 °C

• Throughput: up to 120 samples per working day

• Accelerated heating and cooling – up to 2 hours saved per run

• Enhanced sealing system for safe fume management

• Compatible with KjelSampler K-376/K-377 for full automation

Available models:

• KjelDigester K-446 – manual model with manual rack handling; optional condensate trap

• KjelDigester K-449 – automated model with automatic lift, programmable temperature/time profiles, integrated scrubber control and delayed start for unattended runs

Applications:

• Total Kjeldahl Nitrogen (TKN) and protein determination in food and beverages

• Feed and forage nitrogen analysis

• TKN determination in wastewater and environmental samples

• Fertilizer and chemical industry nitrogen assays

• Compliant with AOAC, ISO and EN reference methods

The BUCHI SpeedDigester K-425, K-436 and K-439 are entry-level infrared digestion systems that use individually controlled heating chambers for rapid, homogeneous sample digestion. Continuous temperature adjustment and IR-based heating enable fast ramp-up while minimizing foaming of sensitive matrices. The series spans 6- and 12-position formats, from a purely manual configuration up to a fully programmable model with digital display, scrubber control and IQ/OQ qualification – so laboratories can match throughput and automation to their workload.

Key specifications:

• Maximum temperature: 580 °C

• Temperature range: 70 - 580 °C (K-425/K-436); 50 - 580 °C (K-439)

• Sample positions: 6 (K-425), 12 (K-436 and K-439)

• Individually controlled heating chambers for rapid, homogeneous heating

• Compatible sample tubes: 100 mL, 300 mL and 500 mL

• Sealed suction module for safe fume management

• Continuous H₂O₂ addition via capillary funnels

Available models:

• SpeedDigester K-425 – 6 positions, manual continuous temperature control, no display

• SpeedDigester K-436 – 12 positions, manual continuous temperature control, no display

• SpeedDigester K-439 – 12 positions, digital display, pre-programmable temperature programs, integrated scrubber control, IQ/OQ qualification capability

Applications:

• Kjeldahl nitrogen and protein determination

• Chemical Oxygen Demand (COD) analysis

• Aqua regia digestion and heavy metal analysis

• Phosphate and hydroxyproline determination

• Applications across food, feed, environmental, chemical and fertilizer industries

The BUCHI Wet Digester B-440 is an ecological pre-incineration unit dedicated to ash determination in pharmaceutical raw materials, foodstuffs and other sample types. It enables parallel ashing of differently sized crucibles at minimal heat loss and supports programmable incineration protocols for reproducible results. A glass hood captures acid fumes, and with the optional Scrubber K-415 accessory harmful vapors are neutralized in four stages before release – dramatically reducing fume hood corrosion and environmental impact.

Key specifications:

• Temperature range: 10 - 600 °C

• Time range: 0 - 240 minutes

• Crucible capacity: 4 or 6 crucibles

• Accommodates differently sized crucibles simultaneously

• Programmable incineration profiles for reproducible digestion

• Integrated glass hood for acid fume capture

• Optional Scrubber K-415 – four-stage fume neutralization controlled via the digester interface

• Compliant with U.S. Pharmacopeia standards <281> and <733>

Applications:

• Ash determination in pharmaceuticals and raw materials

• Sulfated ash testing per USP 281, European and Japanese Pharmacopoeias

• Loss on ignition (LOI) determination

• Environmental sample pre-treatment

• Pre-incineration prior to trace metal analysis