Magnetic extractant with an Fe3O4@SiO2 core and aqueous ammonia coating for microextraction of petroleum acids

Selective Profiling of Carboxylic Acid in Crude Oil by Halogen Labeling Combined with Liquid Chromatography and High-Resolution Mass Spectrometry

Carboxylic acids are a small but essential compound class within petroleum chemistry, influencing crude oil behaviors in production and processing and causing environmental impacts. Detailed structural information is fundamental to understanding their influence on petroleum characteristics. However, characterizing acids in crude oil remains challenging due to matrix effects, structural diversity, and low abundance. In this work, we present a new methodology for profiling carboxylic acids by liquid-liquid extraction and selective derivatization using 4-bromo-N-methylbenzylamine (4-BNMA) followed by liquid chromatography and electrospray ionization Orbitrap mass spectrometry (LC-ESI-Orbitrap MS). The fragmentation of 4-BNMA derivatives produces a unique product ion pair, m/z 169/171, enabling the identification of chromatographic fractions containing carboxylic acids. The mass spectra of the corresponding fractions are extracted, and the acids are further computationally isolated based on the isotopic pattern. The method was optimized and validated using acid standards and systematic experimental designs, assuring robustness and sensitivity for nontarget screening purposes. This method detected up to 380 carboxylic acids in six Danish North Sea crude oils, with up to two carboxyl and other heteroatom functionalities (NSO). The results indicated that the most populated species are fatty acids (double bond equivalent (DBE) = 1) and small aromatic acids (DBE = 2-6). The predominance and diversities of compound classes in different samples are consistent with their corresponding bulk properties. Polyfunctional acids (Ox, NxOx, and SxOx) were observed due to exposure to oxidation and biodegradation. Also, the approach's applicability benefits high-resolution MS analysis by simplifying data processing for crude oil and potentially other high-organic and aqueous samples.

Annulated carbamates are precursors for the ring contraction of the adamantane framework

We report a protocol for the one-pot two-step synthesis of noradamantane methylene amines. The first step is the triflic acid-promoted decarboxylation of adamantane carbamates, which causes rearrangement of the adamantane framework to form noradamantane iminium salts, which are reduced to amines in the second separate step.

Microextraction and its application for petroleum and crude oil samples

Petroleum is an extremely heterogeneous material. It consists of a wide range of aliphatic, aromatic, and compounds containing heteroatoms such as metals, sulfur, and nitrogen. The American Society for Testing and Materials (ASTM) methods are used globally as accepted analytical methods for petroleum, petrochemicals, and fuels. A major drawback of ASTM methods is that they require multistep sample preparation that consumes substantial volumes of samples. Thus, the challenge in the petrochemical analysis is to develop rapid and simpler sample preparation procedures that can be automated. An assessment based on the current literature, specifically on the sample preparation of petroleum samples, leads to the authors' conclusion that microextraction provides an excellent complement to current methods. In this review, solvent and sorbent-based microextraction techniques in the context of the consideration of petroleum and crude oil, and samples related to the petrochemical industry, are discussed.