Quantitative Analysis of Furanic Compounds in Transformer oil by HPLC Method

Importance of the Topic

Monitoring transformer oil for furanic compounds such as 2-furaldehyde is crucial for assessing the degradation of paper insulation and ensuring the reliable operation of power transformers.

Objectives and Overview

This study follows the ASTM D 5837 method to develop a quantitative HPLC approach for five furanic compounds in transformer oil, enabling early detection of paper insulation ageing.

Methodology

Transformer oil samples were spiked and extracted by liquid–liquid extraction using acetonitrile. The extracts were injected (5 µL) into an HPLC system employing gradient elution of water/acetonitrile (85:15 to 0:100) at 1.0 mL/min and 40 °C. Calibration curves were prepared from 50 to 9000 µg/L, and performance was evaluated for linearity, sensitivity, precision, and extraction efficiency.

Instrumentation Used

• Shimadzu Prominence HPLC system with SPD-M20A diode array detector
• Shim-pack GISS column (250 mm × 4.6 mm, 5 µm)
• HPLC-grade acetonitrile and Milli-Q water

Main Results and Discussion

All calibration curves showed excellent linearity (R2 = 0.999). LODs ranged from 2.0 to 6.7 µg/L and LOQs from 6.0 to 20.2 µg/L. Repeatability (RSD) was below 5.7% at all levels. Extraction efficiencies were between 80% and 120%. In real samples, 2-furaldehyde was the predominant compound at 1170.5 µg/L and 826.7 µg/L in two transformer oils; other furanics were below 50 µg/L or not detected.

Benefits and Practical Applications

This method offers sensitive and precise quantitation of furanic markers for transformer diagnostics, supporting preventive maintenance and quality control in electrical utilities and analytical laboratories.

Future Trends and Possibilities

Emerging trends include coupling with mass spectrometry for improved specificity, online monitoring of transformer fluids, method miniaturization, and automated high-throughput workflows for real-time condition assessment.

Conclusion

A robust HPLC protocol compliant with ASTM D 5837 has been established, providing reliable detection and quantification of key furanic compounds to monitor paper insulation health in transformers.

References

1. ASTM D 5837-99 Standard Test Method for Furanic Compounds in Electrical Insulating Liquids by High Performance Liquid Chromatography