Gerhardt VAP500C Automated Kjeldahl Nitrogen Determinator with Auto Sampler

Overview

The Gerhardt VAP500C is a fully automated Kjeldahl nitrogen determinator engineered for high-throughput, regulatory-compliant elemental nitrogen analysis in diverse matrices. It implements classical Kjeldahl digestion–distillation–titration methodology in a single integrated platform, combining precise steam distillation with direct potentiometric pH endpoint detection. Unlike conventional colorimetric titration systems reliant on mixed indicators, the VAP500C employs real-time pH monitoring during acid–base neutralization—ensuring unambiguous endpoint identification, elimination of indicator-related drift, and superior robustness across variable sample matrices. Its design adheres to internationally recognized standards including ISO 8968 (milk and dairy), ISO 1871 (cereals), AOAC 981.10 and 984.13 (food and feed), and USP (pharmaceutical nitrogen assay), making it suitable for GLP- and GMP-regulated environments requiring full auditability and traceability.

Key Features

• Fully automated 20-position sample carousel with pneumatic sample tube handling—enabling unattended operation from sample loading to result reporting.
• Programmable steam generator with adjustable pressure (0–1.2 bar) and soft-start steam initiation (SSS function) to prevent bumping or crystallization-induced carryover during distillation of viscous or reactive samples.
• Precise reagent delivery system: independent programmable dosing of NaOH, boric acid, and dilution water—with optional manual alkaline supplementation during active distillation via front-panel alkaline pump override.
• Integrated potentiometric titration module with direct pH endpoint detection—eliminating need for indicator preparation, minimizing operator variability, and delivering enhanced reproducibility (±1% RSD) across heterogeneous sample types.
• Corrosion-resistant, quick-release polymer distillation head (standard); optional high-purity borosilicate glass head available for high-temperature or aggressive chemical applications.
• Active vacuum-assisted waste evacuation for both distillate receiver and titration waste—preventing clogging, leakage, or manual handling of hot/hazardous effluents.
• Wide-range cooling water flow control (up to 7 L/min) with temperature feedback—optimized for ambient conditions exceeding 35°C, ensuring consistent condensation efficiency year-round.
• Illuminated transparent safety enclosure with interlocked access door—providing full visual process monitoring while meeting IEC 61010-1 safety requirements.

Sample Compatibility & Compliance

The VAP500C supports quantitative nitrogen determination—including total nitrogen, crude protein (×6.25), true protein, non-protein nitrogen (NPN), ammonium salts, and volatile basic nitrogen—in over 100 sample categories. Validated applications span food & beverage (grains, dairy, meat, wine, beer, spirits), agricultural products (feed, fertilizer, soil), environmental samples (sludge, wastewater solids), pharmaceuticals (APIs, excipients), polymers (rubber, starch), and industrial materials (coal, biomass, leather, tobacco). All operational parameters—including reagent volumes, steam ramp profiles, distillation duration, and titration thresholds—are configurable and stored with timestamped audit trails compliant with FDA 21 CFR Part 11 requirements. The system meets CE marking directives (2014/30/EU EMC, 2014/35/EU LVD) and conforms to ISO/IEC 17025 method validation principles when used with certified reference materials (CRMs) such as BCR-68, NIST SRM 8414, or AOAC 990.11.

Software & Data Management

Gerhardt’s proprietary KjelMaster™ software provides intuitive workflow management, method library storage, user-level access control (admin/operator/auditor roles), and electronic signature support. All analytical events—including sample ID assignment, reagent lot tracking, calibration logs, maintenance records, and raw titration curves—are archived in an encrypted SQLite database with automatic daily backup. Export options include CSV, PDF, and XML formats compatible with LIMS integration (via ASTM E1384 or HL7 interfaces). Full 21 CFR Part 11 compliance is enabled through configurable audit trail retention (≥12 months), immutable event logging, and dual-control password protection for critical parameter changes.

Applications

Beyond routine Kjeldahl nitrogen, the VAP500C is routinely deployed for standardized steam distillation assays including: volatile basic nitrogen (VBN) in fish and meat; ammoniacal nitrogen in wastewater; alkali-hydrolyzable nitrogen in soils; nitrate/nitrite after reduction; formaldehyde content via Nash reaction; sulfur dioxide in wines and dried fruits; cyanide and sulfide in environmental extracts; volatile phenols in coal tar; and residual hydrazine in pharmaceutical intermediates. Its modular architecture allows seamless adaptation to AOAC, ISO, DIN, and GB methods—particularly where high recovery (>99.5%), low detection limits (0.1 mg N), and minimal analyst intervention are mandatory.

FAQ

What sample throughput can be achieved with the VAP500C?
With average distillation time of 3 minutes per sample and 20-position auto-sampler, up to 360 analyses can be completed in an 18-hour unattended run.
Is method validation support provided by Gerhardt?
Yes—Gerhardt supplies IQ/OQ documentation templates, performance qualification protocols, and on-site IQ/OQ execution services aligned with ISO/IEC 17025 and GxP expectations.
Can the VAP500C be integrated into an existing LIMS environment?
Yes—via configurable ASCII/CSV export, OPC UA server option, or custom API development upon request.
What maintenance intervals are recommended for routine operation?
Daily: cleaning of condenser and drip tray; weekly: inspection of reagent lines and pump tubing; quarterly: calibration of pH electrode and steam pressure sensor; annually: full preventive maintenance by certified Gerhardt service engineer.
Does the system support dual-wavelength UV detection for post-distillation derivatization?
No—the VAP500C is a dedicated Kjeldahl platform; however, Gerhardt offers complementary UV-Vis spectrophotometers (e.g., SpectroDirect series) for colorimetric post-analysis workflows.