Simultaneous liquid-liquid extraction of dibenzyl disulfide, 2,6-di-tert-butyl-p-cresol, and 1,2,3-benzotriazole from power transformer oil prior to GC and HPLC determination

• Published in: Journal of separation science Vol. 35; no. 5-6; pp. 750 - 757
• Main Authors: Jaber, Abdul Muttaleb Yousef, Mehanna, Nemr Ahmed, Abulkibash, Abdalla Mahmoud
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01-03-2012; Wiley
• Subjects: Analytical chemistry; Applied sciences; BTA / Corrosive sulfur / DBDS / DBPC / Liquid-liquid extraction; Chemistry; Chromatographic methods and physical methods associated with chromatography; Confidence intervals; Corrosion inhibitors; Disulfides; Electrical engineering. Electrical power engineering; Exact sciences and technology; Gas chromatographic methods; Liquid-liquid extraction; Mathematical analysis; Minerals; Other chromatographic methods; Pretreatment; Transformers; Transformers and inductors; Chemical analysis; HPLC chromatography; Flame ionization detector; Solvent extraction; Transformer oil; Corrosion inhibitor; Additive; Organic disulfide; DBDS; Sample preparation; Liquid―liquid extraction; Preservative; Quantitative analysis; Electron capture detector; Liquid liquid extraction; Corrosive sulfur; Antioxidant; BTA; DBPC; Gas chromatography; Reversed phase chromatography; Ultraviolet detector; Butylated hydroxytoluene; Phenols; Benzotriazole
• ISSN: 1615-9306; 1615-9314
• DOI: 10.1002/jssc.201100505

2,6‐Di‐tert‐butyl‐p‐cresol (DBPC), dibenzyl disulfide (DBDS), and 1,2,3‐benzotriazole (BTA) are additives that may be found concomitantly in the oil matrix of power transformer. DBPC and DBDS act as antioxidants while, BTA is a corrosion inhibitor that protects copper conductors inside the transformer unit from corrosion. A powerful analytical method is, therefore, required to determine these additives at trace levels in the transformer oil. This work describes a unique single liquid–liquid extraction pretreatment step prior to the determination of the components by gas chromatography (GC) and high‐performance liquid chromatography (HPLC) techniques. The optimum volume ratio used in the pretreatment step was determined as 5:2:5 for mineral oil/n‐hexane/acetonitrile, respectively. Relatively, the method is simple and quick with a minimal use of solvents. Analytical results indicate that the method is relatively sensitive, accurate, and precise for each of the three components in fresh and used mineral oil. The calibration curves for the three components demonstrate a significant increase in sensitivities. Detection limits found were, 100 mg L−1 (0.01% w/v), 0.80 mg L−1, and 2.04 mg L−1 for DBPC, DBDS, and BTA, respectively. The Student's t values determined at 95% confidence level indicate that there is no significant difference between the experimental means obtained by this method and the standard method for each component.