Installation instruction: MVA-25 – 884 Professional VA fully automated for the determination of antioxidants with auto-matic sample preparation

Význam tématu

Ensuring the stability of lubricants through monitoring antioxidant content is critical for machinery longevity, preventing oxidation-related failures and optimizing maintenance intervals. Automated voltammetric methods deliver fast, reliable data for industrial QA/QC and field laboratories.

Cíle a přehled studie / článku

This bulletin describes the installation and configuration of the MVA-25 system, combining a 884 Professional VA analyzer with an 858 Professional Sample Processor and 807 Dosino units to fully automate sample preparation and voltammetric determination of aromatic amine and hindered phenol antioxidants according to ASTM D6971 and D6810 protocols.

Použitá metodika a instrumentace

Methodology employs linear sweep voltammetry with automatic steps:

• Addition of neutral and alkaline electrolytes to lubricant samples mixed with quartz sand.
• Mechanical agitation by integrated magnetic stirrer.
• Extraction of antioxidants into the electrolyte phase.
• Automated transfer of aliquots to the voltammetric cell via peristaltic pump.
• Electrode cleaning and rinsing cycles of the glassy carbon working and platinum reference/auxiliary electrodes.

Key components:

• 884 Professional VA with RDE head and 807 Dosino units
• 858 Professional Sample Processor with built-in peristaltic pump
• 843 Membrane Pump Station for cell rinsing and draining
• Electrodes: glassy carbon, platinum reference and auxiliary rods
• Sensors and dosing solutions for neutral (acetate/perchlorate) and alkaline (NaOH/ethanol) electrolytes

Hlavní výsledky a diskuse

Electrochemical cleaning restores electrode performance, achieving relative standard deviations below 3% after 10 cleaning cycles. Calibration curves for aromatic amines and phenols show linear response over typical concentration ranges. Tests on in-service oils demonstrate accurate quantification of remaining antioxidants, with remaining amine and phenol levels reported around 70–85% depending on service conditions.

Přínosy a praktické využití metody

The fully automated workflow reduces manual handling to vial loading, improves reproducibility and safety, and increases sample throughput. Combined determination of both antioxidant classes in a single preparation saves time and resources.

Budoucí trendy a možnosti využití

Emerging developments include integration with laboratory information management systems (LIMS), remote monitoring and diagnostics, AI-driven method optimization, and new electrode materials for enhanced sensitivity. Miniaturized flow-through cells and eco-friendly electrolytes may further streamline operations.

Závěr

The MVA-25 automated voltammetric system offers a robust, reliable analysis of lubricant antioxidants, aligned with ASTM standards, ensuring efficient maintenance decisions and improved equipment reliability.

Reference

ASTM International. ASTM D6971-09(2014). Standard Test Method for Measurement of Hindered Phenolic and Aromatic Amine Antioxidant Content in Non-zinc Turbine Oils by Linear Sweep Voltammetry.
ASTM International. ASTM D6810-21. Standard Test Method for Measurement of Hindered Phenolic Antioxidant Content in Non-Zinc Turbine Oils by Linear Sweep Voltammetry.
Metrohm AG. Application Bulletin 445/1: Installation instruction: MVA-25 – 884 Professional VA fully automated for antioxidants, Version 09/2024.