Analysis of Benzotriazole, Tolutriazole Derivatives and Furanic Compounds: Passivators in Insulating Oil

Significance of the Topic

This method addresses the need to quantify benzotriazole-based passivators and furanic compounds in insulating oils, crucial to monitor degradation, assess oil quality, and comply with internationally recognized standards such as BS148:2009 and ASTM D5837-15.

Aims and Overview of the Study

The study aims to establish a rapid, sensitive, and reliable reversed-phase liquid chromatography method using Shim-pack VP-ODS column for the simultaneous determination of 1,2,3-benzotriazole, N-bis[2-ethylhexyl]-aminomethyltolutriazol, and five furanic compounds at microgram-per-liter levels.

Methodology and Instrumentation

• Instrument: Shimadzu Prominence-i LC system
• Column: Shim-pack VP-ODS (250 × 4.6 mm, 5 μm)
• Mobile Phase: Gradient elution with water (A) and acetonitrile (B); 15–45 % B (0–10 min), 100 % B (10.01–20 min), 15 % B (20.01–30 min)
• Flow Rate: 1.0 mL/min; Column Temperature: 40 °C; Injection Volume: 15 μL
• Detector: Photodiode array at 220, 260, and 280 nm

Main Results and Discussion

The method achieved baseline separation of all analytes within a 30-minute run time. Calibration levels ranged from 1,000 µg/L (furanic compounds) to 20,000 µg/L (benzotriazoles), demonstrating linearity and sensitivity compatible with standard requirements. Detector wavelengths were selected to optimize sensitivity for different compound classes.

Benefits and Practical Applications of the Method

• Simultaneous quantification of multiple passivators and degradation markers in insulating oils
• Compliance with BS148:2009 and ASTM D5837-15 for quality control
• Robust gradient program ensuring reproducibility and minimal carryover
• Adaptable to routine laboratory and field analyses for preventive maintenance

Future Trends and Potential Applications

The method can be further refined by coupling with mass spectrometric detection for enhanced selectivity, employing sub-2 µm particles in UHPLC format to reduce analysis time, and integrating online monitoring for real-time assessment of oil degradation in power transformers.

Conclusion

The developed LC-PDA method provides a streamlined approach for the accurate determination of benzotriazole passivators and furanic degradation products, supporting oil quality assessment and compliance with industry standards.

References

• Shimadzu Application News L576, First Edition Dec. 2021