Investigation of isomeric structures in a commercial mixture of naphthenic acids using ultrahigh pressure liquid chromatography coupled to hybrid traveling wave ion mobility-time of flight mass spectrometry

Analytical chemistry solutions to hazard evaluation of petroleum refining products

Products of petroleum refining are substances that are both complex and variable. These substances are produced and distributed in high volumes; therefore, they are heavily scrutinized in terms of their potential hazards and risks. Because of inherent compositional complexity and variability, unique challenges exist in terms of their registration and evaluation. Continued dialogue between the industry and the decision-makers has revolved around the most appropriate approach to fill data gaps and ensure safe use of these substances. One of the challenging topics has been the extent of chemical compositional characterization of products of petroleum refining that may be necessary for substance identification and hazard evaluation. There are several novel analytical methods that can be used for comprehensive characterization of petroleum substances and identification of most abundant constituents. However, translation of the advances in analytical chemistry to regulatory decision-making has not been as evident. Therefore, the goal of this review is to bridge the divide between the science of chemical characterization of petroleum and the needs and expectations of the decision-makers. Collectively, mutual appreciation of the regulatory guidance and the realities of what information these new methods can deliver should facilitate the path forward in ensuring safety of the products of petroleum refining.

Ion mobility-mass spectrometry for the separation and analysis of procyanidins

Procyanidins are polymeric flavan-3-ones occurring in many plants with antioxidant and other beneficial bioactivities. They are composed of catechin and epicatechin monomeric units connected by single carbon-carbon B-type linkages or A-type linkages containing both carbon-carbon and carbon-oxygen-carbon bonds. Their polymeric structure makes analysis of procyanidin mixtures always difficult. Evaluation of procyanidins according to degree of polymerization (DP) using high-performance liquid chromatography (HPLC) is time-consuming and at best has resolved polymeric families up to DP-17. To expedite studies of procyanidins, the utility of positive ion electrospray ion mobility-mass spectrometry (IM-MS) was investigated for the rapid separation and characterization of procyanidins in mixtures. Applying IM-MS to analyse structurally defined standards containing up to five subunits, procyanidins could be resolved in less than 6 ms not only by degree of polymerization but also by linkage type. A-type procyanidins could be resolved from B-type and both could be at least partially resolved from mixed-type procyanidins of the same DP. IM-MS separated higher order procyanidins with DP of at least 24 from extracts of cranberry. As DP increased, the abundances of multiply-charged procyanidins also increased. During IM-MS of ions of similar m/z, the ion drift times decreased inversely with increasing charge state. Therefore, IM-MS was shown to separate mixtures of procyanidins containing at least 24 interconnected subunits in less than 16 ms, not only according to DP, but also according to linkage type between subunits and charge state.