Profiling naphthenic acids in produced water using hollow fiber liquid-phase microextraction combined with gas chromatography coupled to Fourier transform Orbitrap mass spectrometry

Author(s)

Porto, Nathalia de Aguiar ^[1] ; Crucello, Juliana ^[1] ; Facanali, Roselaine ^[1] ; Medeiros Junior, Iris ^[2] ; Carvalho, Rogerio Mesquita ^[2] ; Hantao, Leandro Wang ^[1]

Affiliation

^[1] Univ Estadual Campinas, Inst Chem, 270 Monteiro Lobato, Campinas, SP - Brazil

^[2] Leopoldo Americo Miguez Mello Res & Dev Ctr, BR-20031912 Petrobras, RJ - Brazil

• Document type: Journal article
• Source: Journal of Chromatography A; v. 1655, OCT 11 2021.
• Web of Science Citations: 0

Abstract

In this study, we describe the development of an analytical method to profile naphthenic acids (NAs) from produced water (PW). The NAs were isolated by hollow fiber liquid-phase microextraction (HF-LPME). A microwave-assisted methylation method was used to convert the free acids into its corresponding naphthenic methyl esters (NAMEs). The best reaction conditions were ascertained using central composite design. The optimized sample preparation method exhibited an improved analytical eco-scale value (80 vs. 61) compared to conventional liquid-liquid extraction. Although the primary goal was qualitative analysis of NAMEs (e.g., group-type separation) in produced water, the quantitative performance was also evaluated for future investigations. The instrumental detection and quantification limits were 0.10 ng mL(-1) and 0.16 ng mL(-1), respectively, using full spectrum data acquisition. The accuracy and precision of the proposed method ranged from 90.4 to 96.6 % and 3.3 to 13.1 %, respectively, using matrix-matched working solutions (0.1, 0.5, and 1.0 mu g mL(-1)). The monoisotopic masses of the adduct ions ({[}M + H](+)) and its corresponding fine isotopic patterns were used to determine the elemental composition of the NAMEs in the PW samples. Qualitative analysis indicated the O-2 class as the predominant class in all samples with carbon numbers ranging from C-5 to C-19 and double bond equivalent (DBE) values of 1 to 8. Additional classes of polar compounds, i.e., O-3, O-4 and nitrogen-containing classes, are reported for the first time by gas chromatography coupled to Fourier transform Orbitrap mass spectrometry and chemical ionization. (C) 2021 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 14/50867-3 - INCT 2014: National Institute of Science and Technology in Bioanalysis
• Grantee: Marco Aurelio Zezzi Arruda
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 20/01064-6 - Analytical developments to study real samples from oil spill in Pernambuco coast: simulations, chemical characterization and ecotoxicity bioassays
• Grantee: Leandro Wang Hantao
• Support Opportunities: Regular Research Grants