Ultra-trace analysis of furanic compounds in transformer/rectifier oils with water extraction and high-performance liquid chromatography

Abstract

A novel approach for the determination of parts-per-billion level of 5-hydroxymethyl-2-furaldehyde, furfuryl alcohol, furfural, 2-furyl methyl ketone, and 5-methylfurfural in transformer or rectifier oils has been successfully innovated and implemented. Various extraction methods including solid-phase extraction, liquid-liquid extraction using methanol, acetonitrile, and water were studied. Water was by far the most efficient solvent for use as an extraction medium. Separation of the analytes was conducted using a 4.6 mm × 250 mm × 3.5 μm Agilent Zorbax column while detection and quantitation were conducted with a variable wavelength UV detector. Detection limits of all furans were at 1 ppb v/v with linear ranges range from 5 to 1000 ppb v/v with correlation coefficients of 0.997 or better. A relative standard deviation of at most 2.4% at 1000 ppb v/v and 7.3% at 5 ppb v/v and a recovery from 43% to 90% depending on the analyte monitored were obtained. The method was purposely designed to be environmental friendly with water as an extraction medium. Also, the method uses 80% water and 20% acetonitrile with a mere 0.2 mL/min of acetonitrile in an acetonitrile/water mixture as mobile phase. The analytical technique has been demonstrated to be highly reliable with low cost of ownership, suitable for deployment in quality control labs or in regions where available analytical resources and solvents are difficult to procure.

Selective Aqueous Extraction and Green Spectral Analysis of Furfural as an Aging Indicator in Power Transformer Insulating Fluid

“…The resulting concentrations of the three samples obtained by selective aqueous extraction coupled with a UV-Vis spectral analysis can be compared to validate the accuracy and applicability with other conventional methods such as the ASTM D5387 method, HPLC, and aniline-acetate colorimetric analysis [23,24] (Figures 5 and 6).…”

“…Although these methods have provided accurate and reproducible results, they have several drawbacks, such as a time-consuming sample preparation protocol and the use of expensive instrumentation, that limit their application [21]. The detection of furanic compounds from the UV-visible region up to the mid-infrared region [22][23][24] has highlighted the advantages and provided good correlations with the conventional methods, but the detection at the UV-visible region can be affected by the color intensity of the insulation oil [25] and the conducting materials in the insulation oil [26].…”

Concentration of 5‐hydroxymethylfurfural produced by insulating paper in an oil–paper insulation system

“…These advantages give it a broad research prospect. Studies have now been conducted on the concentration of 5‐hydroxymethylfurfural and its detection methods , but its concentration change during the aging of insulating paper has not been regularly detected. Currently, the reported methods for measuring 5‐hydroxymethylfurfural are chromatography and spectrophotometry .…”

Separation of six xanthones from Swertia franchetiana by high‐speed countercurrent chromatography

“…Other technology such as silica gel and macroporous resin column chromatography was commonly used with LLE to efficiently enrich the target compounds . Interestingly, good extraction results were obtained in preliminary study by an innovative LLE method with extraction solvent system composed of water, ethyl acetate, and petroleum ether . Based on this, we developed an efficient extraction solvent system composed of water, methanol, and petroleum ether to enrich the above‐mentioned xanthones from S. franchetiana .…”