Fractionation of oil sands-process affected water using pH-dependent extractions: A study of dissociation constants for naphthenic acids species

Trace analysis of total naphthenic acids in aqueous environmental matrices by liquid chromatography/mass spectrometry-quadrupole time of flight mass spectrometry direct injection

“…Additionally, while the interdependence of pH, concentration, and chemical characteristics of NAs is complex, it is well known that acid pH can lead to precipitation. In support of the current use of pH >10, a recent publication indicates that the vast majority of all oxy-NAs are extracted at this pH [22]. Merichem naphthenic acid technical mixture was found to be poorly soluble in water, while the presence of acetic acid (0.1% v/v, pH ∼3) decreased the isomer response factors and the stability in prepared samples significantly ( Fig.…”

“…A comparable LC/MS-QToF method published by Hindle et al [24], using a 5 L injection volume of samples at 10× dilution with 50% acetonitrile and 0.1% acetic acid, was able to achieve a method detection limit of 1 g mL −1 using a Sigma-Aldrich technical NA mixture. A recently published work by Huang et al [22] focused on aspects of OSPW fractionation at various pH ranges and employed a UPLC/QToF method, although method performance and standard details were not provided. While the pH results complimented our methodology, the use of solvent based samples was not applicable to the direct routine analysis of environmental waters.…”

“…Similarly, Martin et al [28] prepared OSPW solutions in 50% acetonitrile containing 0.1% ammonium hydroxide and OSPW samples were diluted to 60% methanol. Huang et al [22] also prepared sample extracts in acetonitrile/methanol. Our use of alkali rather than organic solvent allowed for less sample dilution.…”

“…A further consideration with respect to NA analysis is the observation that the clean-up procedure (including solvents, acidification, ion exchange) employed can be selective with respect to the compounds extracted [18][19][20][21][22]. It is therefore apparent that not only will the observed NA profile vary depending upon both the source and age of the sample, but also upon sample preparation and instrument conditions used.…”

Solubilized Chitosan Biopolymers for Sequestration of Organic Acids in Aquatic Environments after Biodegradation in a Constructed Wetland Treatment System

“…Thus, the use of conditions in aqueous media that lie below pH 6 led to protonation of the glucosamine groups of chitosan. In contrast, the pKa for naphthenate components (O2, O3, and O4 species) in OSPW resides across a range of pKa value between 3.5-7 (Armstrong et al, 2009;Huang et al, 2015). In typical OSPW environments, the media are somewhat alkaline (ca.…”