Wax deposit is of a great concern in the petroleum industry and causes partial or total blockage of the pipelines. In this work, four Brazilian crude oils (P1-P4) and five inhibitors solutions (I1-I5) were used associating rheology results to understand, at a molecular level, the characteristics of the saturated fractions by high-resolution mass spectrometry (Orbitrap coupled to atmospheric pressure chemical ionization (APCI) source) and two-dimensional gas chromatography coupled to mass spectrometry (GC × GC-MS). The effectiveness of wax inhibitors can be demonstrated by the viscosity decrement. The characterization of the saturated fractions by GC × GC-MS and high resolution mass spectrometry showed that is possible to conclude that inhibitor I1 favored the inhibition process of paraffins when oils have a smaller and monocyclic saturated chain hydrocarbon (HC) profiles, whereas for oils with larger amounts of polycyclic chain HCs, the inhibitor I4 appeared to be the alternative.

Hydrocarbons present in saturated fractions of crude oils can be assessed by atmospheric pressure chemical ionization (APCI) using small hydrocarbons as ionizing reagents in a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). In this work, five paraffin standards of different average molar mass distributions (Mw) were easily ionized by APCI(+)FT-ICR MS using isooctane as the reagent gas. Data of Mw, carbon number and double bond equivalent (DBE) distributions corresponding to linear and cyclic hydrocarbons (HCs) were compared to results obtained from analysis of high temperature gas chromatography with a flame ionization detector (HTGC-FID), comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC×GC-MS) and 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. APCI(+)FT-ICR MS data showed good agreement with those of analytical techniques. Furthermore, the ability of APCI(+) to assess n-paraffin, even in blends with polyaromatic hydrocarbon molecules such as coronene (Mw = 301 Da) at concentrations from 2.5 to 25 µg mL-1, was demonstrated. The typical MS paraffin profile (containing repeating mass units of 14 Da) was clearly confirmed, being totally suppressed when a concentration of 25 µg mL-1 of coronene was used. This phenomenon was also evidenced in one of two saturated fractions produced using saturates, aromatics and polar (SAP) compound fractionation methodology.

The Cannabis sativa L. plant has a complex chemical composition, containing various chemical compounds such as terpenes, sugars, hydrocarbons, steroids, flavonoids, and amino acids. Few works have attempted to identify the constitutional isomers of cannabinoids that are found in the plant. The present study reported the analysis of seven cannabinoid standards: five neutral and two acidic, as well as Cannabis products (hashish and marijuana) and parts of the Cannabis plant (flower and leaf) using mono-dimensional gas chromatography coupled with mass spectrometry (GC-MS) and two-dimensional gas chromatography coupled with quadrupole MS (GC × GC-QMS), ultra performance liquid chromatography coupled with electrospray ionization-quadrupole-time of flight (UPLC-ESI-QTOF)-MS and UPLC-ESI-travelling wave ion mobility (TWIM)-MS. The results of GC-MS demonstrated close retention times (∆tR = 1.303 min) in separation of the five cannabinoid standards, whereas GC × GC-QMS provided a substantially better identification and distinction of constitutional isomers of cannabinoids, where a total of 11 cannabinoids were identified in the hashish sample. UPLC-QTOF-MS and UPLC-TWIM-MS data obtained complete chemical information, in which ESI(+) revealed the presence of seven constitutional isomers of ∆9-tetrahydrocannabinol (∆9-THC), whereas ESI(-) proved the presence of four isomers of ∆9-tetrahydrocannabinolic acid A (∆9-THCA A).