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Silver nano-bulks surface-enhanced Raman spectroscopy used as rapid in-situ method for detection of furfural concentration in transformer oil

Furfural concentration is an important indicator for the aging diagnosis of internal paper insulation in power transformers. Surface-enhanced Raman scattering (SERS) could directly perform rapid in-situ detection without complex preprocessing steps, which makes SERS suitable for online monitoring. The application of SERS in the detection of furfural concentration in transformer oil was investigated. First, sliver nano-bulks (AgNBs) were synthesized successfully on the copper foil surface by the galvanic displacement. The electric field distributions of AgNBs were analyzed theoretically using the COMSOL software, which indicated that the AgNBs were suitable for SERS application. Then, AgNBs were used as the SERS substrate to detect standard transformer oil samples with different furfural concentrations. As a result, the Raman spectral peak at 1571 cm−1 was selected as the characteristic SERS spectral peak of furfural dissolved in transformer oil for qualitative and quantitative analyses. Subsequently, the Raman spectral peak ratio I1571/I1597 was used as the furfural function in oil to construct the quantitative analysis model using the least squares method. Results showed that SERS method could be used to analyze the furfural dissolved in transformer oil quantitatively and effectively. With further improvements of the detection limit, the SERS method will provide a useful approach to achieving rapid in-situ analysis for furfural dissolved in transformer oil.