1 3 DOI 10.1007/s10337-017-3315-1 Chromatographia SHORT COMMUNICATION Static Headspace GC/MS Method for Determination of Methanol and Ethanol Contents, as the Degradation Markers of Solid Insulation Systems of Power Transformers Hoda Molavi 1 · Abbas Yousefpour 1 · Akbar Mirmostafa 2 · Ali Sabzi 3 · Sepideh Hamedi 4 · Milad Narimani 1 · Nazanin Abdi 1 Received: 22 November 2016 / Revised: 7 April 2017 / Accepted: 19 April 2017 © Springer-Verlag Berlin Heidelberg 2017 issues for utilities. Therefore, considering an appropriate diagnostic method is essential to prevent unexpected fail- ures and improve the reliability of the equipment. It is more than a century that cellulose, a natural poly- mer containing alpha-D-glucose units, together with min- eral oil is being employed in transformers as the insulating system [1]. Plenitude in the nature, good mechanical and electrical characteristics, along with its ease of use in fabri- cating operation led to cellulose wide application [1]. Due to the fact that the solid insulation system cannot be easily replaced as the insulating oil, the age of a trans- former is evaluated by the health of its solid insulation [2, 3]. Indeed, the extent of insulation paper degradation is determinative of the remaining life of a solid insulation and subsequently a transformer [4]. A factor to evaluate the age and the quality of the cel- lulose insulator is degree of polymerization (DP). This direct technique is one of the most important tools to evaluate the lifetime of the paper. New paper has a DP value of about 1200, which would be reduced to 1000 after applying the drying process, while the water content is about 0.5%. Reaching a DP value of 200 means that the tensile strength of the paper has decreased to 20% of its original value and the transformer life is over [5–7]. Although the measurement of paper’s DP (according to IEC 60450 [8] or ASTM D4243 [9]), as a direct way, pro- vides useful information, but it is impossible to access internal insulation for paper sampling during transformer regular operation [2]. Utilities are interested in indirect and non-destructive diagnostic methods for determination of the residual life of their power transformers, which could be applied easily for an operating transformer. One of the non-destructive diag- nostic techniques is using chemical markers, such as car- bon dioxides and furanic derivations, in the oil. Abstract Methanol in insulating oil has been proposed as a new marker for condition assessment of the solid insu- lation system of power transformers. In the current work, as a first step of using the new marker, an analytical static headspace gas chromatography/mass spectrometry method has been developed, optimized, and validated to measure methanol and ethanol contents in the insulating mineral oil. The analyzing setup consists of a 6890 N gas chroma- tograph equipped with a 5973 network mass spectrometer (MS) in the absence of a costly headspace autosampler, and the chromatography separation was performed on a 60 m × 320 μm × 0.5 μm VF-WAXms GC column. Cali- bration curves have been provided using several concen- trations of the alcohols, and also limit of detection (LOD), limit of quantification (LOQ), and relative standard devia- tion percentage (RSD%) have been determined. Keywords Gas chromatography · Static headspace · Oil analysis · Methanol · Insulating paper · Paper degradation · Power transformer Introduction Power transformers are vital equipment in electrical net- works, and their health and life expectancy are important * Hoda Molavi hmolavi@nri.ac.ir 1 Niroo Research Institute, Tehran, Iran 2 Zangan Industrial Oil Refining Company, Zanjan, Iran 3 Oil and Fuel Laboratory, Niroo Research Institute, Tehran, Iran 4 Shahid Beheshti University, Tehran, Iran