Dielectric mineral oils are used to impregnate power transformers and large electrical apparatus, acting as both liquid insulation and heat dissipation media. Antioxidants and passivators are frequently added to mineral oils to enhance oxidation stability and reduce the electrostatic charging tendency, respectively. Since existing standard test methods only allow analysis of individual additives, new approaches are needed for the detection of mixtures. For the first time we investigate and discuss the performance of analytical methods, which require or do not require extraction as sample pretreatment, for the simultaneous reversed-phase high-performance liquid chromatography determination of passivators (benzotriazole, Irgamet(®) 39) and antioxidants (N-phenyl-1-naphtylamine, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol), chosen for their presence in marketed oils. Quick easy, cheap, effective, rugged and safe and solid phase extractions were evaluated as sample pretreatments. Direct sample-injection was also studied. Ultraviolet spectrophotometry and direct-current coulometry detection were explored. As less prone to additive concentrations variability, the direct-injection high-performance liquid chromatography with ultraviolet and coulometric detection method was validated through comparison with Standard Method IEC 60666 and through an ASTM interlaboratory proficiency test. Obtained detection limits are (mg kg(-1) ): benzotriazole (2.8), Irgamet(®) 39 (13.8), N-phenyl-1-naphtylamine (11.9), 2,6-di-tert-butylphenol (13.1), 2,6-di-tert-butyl-p-cresol (10.2). Simultaneous determination of selected additives was possible both in unused and used oils, with good precision and accuracy.

Simultaneous determination of five common additives in insulating mineral oils by high-performance liquid chromatography with ultraviolet and coulometric detection

BRUZZONITI, Maria Concetta;SARZANINI, Corrado;RIVOIRA, LUCA;
2016

Abstract

Dielectric mineral oils are used to impregnate power transformers and large electrical apparatus, acting as both liquid insulation and heat dissipation media. Antioxidants and passivators are frequently added to mineral oils to enhance oxidation stability and reduce the electrostatic charging tendency, respectively. Since existing standard test methods only allow analysis of individual additives, new approaches are needed for the detection of mixtures. For the first time we investigate and discuss the performance of analytical methods, which require or do not require extraction as sample pretreatment, for the simultaneous reversed-phase high-performance liquid chromatography determination of passivators (benzotriazole, Irgamet(®) 39) and antioxidants (N-phenyl-1-naphtylamine, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol), chosen for their presence in marketed oils. Quick easy, cheap, effective, rugged and safe and solid phase extractions were evaluated as sample pretreatments. Direct sample-injection was also studied. Ultraviolet spectrophotometry and direct-current coulometry detection were explored. As less prone to additive concentrations variability, the direct-injection high-performance liquid chromatography with ultraviolet and coulometric detection method was validated through comparison with Standard Method IEC 60666 and through an ASTM interlaboratory proficiency test. Obtained detection limits are (mg kg(-1) ): benzotriazole (2.8), Irgamet(®) 39 (13.8), N-phenyl-1-naphtylamine (11.9), 2,6-di-tert-butylphenol (13.1), 2,6-di-tert-butyl-p-cresol (10.2). Simultaneous determination of selected additives was possible both in unused and used oils, with good precision and accuracy.
JOURNAL OF SEPARATION SCIENCE
39
15
2955
2962
Antioxidants; Coulometric detection; Inhibitors; Mineral oil; Monitoring
Bruzzoniti, Maria Concetta; Sarzanini, Corrado; Rivoira, Luca; Tumiatti, Vander; Maina, Riccardo
File in questo prodotto:
File Dimensione Formato  
Bruzzoniti_JSS_per open access_4aperto.pdf

accesso aperto

Descrizione: Articolo per open access
Tipo di file: POSTPRINT (VERSIONE FINALE DELL’AUTORE)
Dimensione 1.34 MB
Formato Adobe PDF
1.34 MB Adobe PDF Visualizza/Apri
Bruzzoniti_et_al-2016-Journal_of_Separation_Science.pdf

non disponibili

Descrizione: Articolo pdf editoriale come pubblicato
Tipo di file: PDF EDITORIALE
Dimensione 431.61 kB
Formato Adobe PDF
431.61 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2318/1589397
Citazioni
  • ???jsp.display-item.citation.pmc??? 1
  • Scopus 3
  • ???jsp.display-item.citation.isi??? 5
social impact