Improved method for detecting methanol in transformer oil based on colorimetry with a chemometric method

The concentration of methanol in transformer oil has proved to be an effective indicator in the aging of paper/oil insulation. Traditional methods for detecting the concentration of methanol in transformer oil use gas chromatography (GC) and gas chromatography-mass spectrometer (GC-MS). Because these traditional methods are time consuming and are high skill operations, an improved method for detecting the concentration of methanol, which is rapid and is a lower skill operation, is proposed in this paper. This method detects the concentration of methanol using spectroscopy. Potassium permanganate is added to oxidize methanol into formaldehyde, which reats with chromotropic acid producing a mauve complex. From processing the spectrum of the complex using partial least squares, the linear correlation coefficient is increased to 0.999 and the minimum detected concentration is down to 10 parts per billion.