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The application research of solid‐phase extraction and headspace gas chromatography in the detection of methanol in transformer oil

Methanol in transformer oil has been recently proposed as new marker of the aging of solid insulation in power transformers. Because the concentration of methanol in transformer oil is usually less than 500 µg/l and even less than 50 µg/l that cannot be detected by common methods. This paper combined static headspace sampling and solid‐phase extraction (SPE) as pretreatment, used SPE to adsorb and concentrate sample, headspace sampling to desorb and inject methanol in to the gas chromatography. The experiments show that it will achieve the optimal performance when headspace conditions were the equilibrium temperature of 90°C and the equilibrium time of 25 min. The linear relation between the concentration of methanol and the peak area was satisfying in the concentration range from 10 to 600 µg/l with goodness of fit of 0.997. In addition, this method can be applied in practical work. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.