Chemical Speciation of Calcium and Sodium Naphthenate Deposits by Electrospray Ionization FT-ICR Mass Spectrometry

Abstract

Calcium and sodium naphthenates are solid deposits and emulsions formed by the interaction of naphthenic acids with divalent (Ca2+, Mg2+) or monovalent (Na+, K+) ions in produced waters. Calcium naphthenate formation, an interfacial phenomenon, is thought to depend largely on tetraprotic naphthenic acids known as “ARN” acids (∼C80) in the crude oil, whereas sodium naphthenates originate from lower molecular weight (C15 to C35) monoprotic naphthenic acids. Here we present detailed chemical heteroatom class composition analyses of calcium and sodium naphthenates from the field based on high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). In all cases, calcium naphthenate deposits consist predominately of tetraprotic acids with a C80 hydrocarbon skeleton whereas sodium naphthenate emulsions consist mainly of specific monoprotic saturated carboxylic acids. Furthermore, low molecular weight tetraprotic (ARN) acids with C60−77 hydrocarbon skeletons were identified in the calcium naphthenate deposit. The high resolution and mass accuracy of FT-ICR MS provide detailed acidic speciation for the analyzed deposits and emulsions.

Transmission Geometry Laser Desorption Atmospheric Pressure Photochemical Ionization Mass Spectrometry for Analysis of Complex Organic Mixtures

“…26 Other low-abundance ions of m/z 900−1200 derive from carboxylic acids with eight oxygen atoms with C 60 −C 79 backbone and DBE 8−10 ( Figure 5, left inset) consistent with prior ESI results for the same sample. 26 In contrast to ESI, only singly charged ions are observed by LD/APPCI, providing a simpler mass spectrum. Singly charged analytes up to m/z 1900 are produced by LD/APPCI.…”

“…The most abundant class is O 2 , dominated by species of DBE = 1 ( Figure 6, bottom inset), namely, saturated straight-chain carboxylic acids with general formula C n H 2n+1 COOH, n = 15−36, spanning a wider range than observed by ESI. 26 Lower-abundance carboxylic acids up to DBE 14 are also observed for that class by LD/APPCI, most of which are not observed by ESI (DBE > 5), 26 probably due to ionization suppression or loss during sample extraction steps prior to ESI analysis. The higher abundance of the saturated acyclic carboxylic acids in the emulsion is due to their surfactant-like character, which increases their ability to bind monovalent cations in oil/salt water media.…”

“…26 The prominent peak at m/z 1230.0632 corresponds to the deprotonated species of elemental composition, C 80 H 142 O 8 , assigned as the tetraprotic naphthenic acid of DBE 10, depicted in Figure 5 (top right, inset). 26 Other low-abundance ions of m/z 900−1200 derive from carboxylic acids with eight oxygen atoms with C 60 −C 79 backbone and DBE 8−10 ( Figure 5, left inset) consistent with prior ESI results for the same sample. 26 In contrast to ESI, only singly charged ions are observed by LD/APPCI, providing a simpler mass spectrum.…”

Sunlight creates oxygenated species in water-soluble fractions of Deepwater horizon oil

“…The most acidic compounds in petroleum correspond to the naphthenic (non-aromatic) acids (carboxylic acids) [46], which correspond to O 2 species with DBE 1-3. For O 2 and O 3 classes, compounds with DBE 5-15 and C 10 -C 30 were detected from dark Macondo-derived water-soluble acids, which were previously attributed to aromatic acids by Stanford et al [24].…”

Going Beyond the Analysis of Common Contaminants: Target, Suspect, and Non-Target Analysis of Complex Environmental Matrices by High-Resolution Mass Spectrometry

“…FT-MS, on the other hand, provides the possibility to extend this range up to C 100 , and to analyze nonvolatile and/or highly polar compounds (Mapolelo et al, 2009;Qian et al, 2001a;Qian et al, 2001b).…”