High-Performance Liquid Chromatography (HPLC) is a reliable method to perform furan analysis on transformer oil. The standards are IEC 61198 and ASTM D5837.

IEC 61198: Method for the determination of 2-furfural and related compounds in mineral insulating oils.

This International Standard specifies test methods for the analysis of 2-furfural and related furan compounds resulting from the degradation of cellulosic insulation and found in mineral insulating oil samples taken from electrical equipment.

2-furfural and related furan compounds dissolved in mineral oil are analysed by high performance liquid chromatography (HPLC). Prior to HPLC analysis, furan derivatives are extracted from the oil by use of a suitable extraction method such as liquid-liquid extraction (method A) or solid-phase separation on a silica cartridge (method B).

ASTM D5837: Standard test method for furanic compounds in electrical insulating liquids by High-Performance Liquid Chromatography (HPLC).