Journal of Analytical & Bioanalytical Techniques
Open Access

Analytical chemistry; Crude oils; Petroleum refining; Products

Introduction

Depending on where they come from, crude oils are extremely complex, naturally occurring compounds that have a wide range of molecular compositions. They are made up of a variety of components, mostly hydrocarbons but also other organic and inorganic molecules. Every year, close to 100 billion barrels of crude oil are extracted, distributed, and processed into numerous refined petroleum products. In order to meet the performance requirements of the end products, the refining process (fractional distillation and/or cracking followed by additional processing through solvent extraction, hydrodesulfurization, or hydrogenation) and the type of crude oil from which it was derived both affect the chemical composition of petroleum refining products. Products of petroleum refining are highly produced compounds, thus their potential dangers and hazards to human and environmental health are closely examined. Petroleum substances are the archetypal examples of a [1-5] broad class of substances known as substances of unknown, variable composition, complex reaction products, or biological materials (UVCBs) because of their inherent complexity and variability in composition. These substances pose particular difficulties for regulatory agencies, particularly when it comes to characterising their chemical makeup.

Materials and Methods

It is important to keep in mind that the language used by the various academic, industrial, and regulatory research sectors can vary. Petroleum refining byproducts are frequently referred to as “hydrocarbon mixtures” by analytical researchers, which are in turn a subset of the larger “complex mixtures” family of samples. The term “mixture” is avoided by the industry and decision-makers because they believe that most products made from oil that are sold in commerce are the result of refining rather than mixing. As a result, these products are referred to as petroleum UVCBs to distinguish them from mixtures found in the environment. Over 80 years have passed since studies of the molecular makeup of crude oils and petroleum refining products began. Historically, the physical-chemical characteristics of petroleum compounds, such as flash [2-4] points and vapour pressure, that were relevant to the product’s usefulness were tracked during the analytical characterisation process. With the development of spectroscopy and mass spectrometry techniques, it is now possible to gradually grasp chemical composition in greater depth; nonetheless, there is still a paucity of information on the ingredients in registered petroleum products. Mass spectrometer resolution, ionisation methods to access a larger range of components, separation methods to provide structural insights, and data display through standardised diagrams have all recently been improved. These developments opened up new possibilities for comprehensively characterising these complex chemicals and addressing regulatory requirements for their composition, their quantity of potentially hazardous components, and their level of variability among manufacturing batches. A subfield of analytical chemistry called “petroleomics” aims to identify all of the components of crude oil and petroleum refining products using high resolution mass spectrometry methods. The range and types of mass spectrometry techniques that can be used for the analysis of samples derived from the study of petroleum are quite diverse. With the exception of GC GC-FID-derived data, there has been relatively little use of the data from these new methods and instruments in regulatory submissions, or even their mention in reviews or original research publications, despite significant advancements in the continuously improving analytical resolution of individual molecules and their classes in oils and complex petroleum UVCBs. The fields of regulatory science and analytical chemistry coexist and are both extremely specialised, requiring a great deal of knowledge.

Discussion

As a result, the researchers that create and improve advanced methodologies for petroleomics frequently lack familiarity with the nuances of the legal mandates controlling regulatory decisionmaking. The most recent opportunities that analytical chemistry has to offer might not be known to decision-makers. Collectively, there is a substantial gap in the application of knowledge from analytical laboratories with a petroleomics focus. In order to show how current petroleomics approaches could be used to meet these needs, this paper first summarises the regulatory advice regarding the chemical composition of petroleum UVCBs. Recent developments in petroleomics applications that are poised to address these needs, along with recent additions to the European Union (EU) Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulatory guidance for demonstrating the composition of complex UVCBs (ECHA, 2022), create a special opportunity to bridge the gap. Here, we emphasize the possibilities for applying [6-10] cuttingedge analytical and data analysis/visualization approaches to make significant judgments regarding petroleum UVCBs that are already within reach. We believe that for rules to be appropriately stringent yet feasible in terms of their attainment using the best available knowledge, decision-makers must be aware of the potential and constraints of present analytical methodologies (Figure 1).

Figure 1: Sampling and sample preparation.

What information do the decision-makers seek on petroleum UVCBs?

The United States and the European Union have supplied the most useful recommendations for the industry on petroleum UVCBs.

Conventional methods for characterization of petroleum substance identity and composition

Numerous techniques for characterizing the physical-chemical characteristics and chemical make-up of oil have also been used to characterize petroleum UVCBs. Due to the huge variety of elements with drastically differing compositions, volatilities, and polarities, numerous approaches are employed.

High and ultrahigh resolution mass spectrometry techniques

Over the past 80 years, developments in mass spectrometry have given rise to the use of high-resolution methods for the molecular analysis of petroleum compounds.

Ultrahigh resolution MS data processing and visualizations Exploiting the patterns of different chemical groups can help with complex material analysis because petroleum hydrocarbons include highly comparable series of hydrocarbon molecules. Sorting molecules into homologous series is made easier by the Kendrick mass defect (KMD) analysis technique.

Declaration of competing interest

The authors reaffirm that they are not aware of any personal or financial conflicts that might have appeared to affect the research described in this paper.

Conclusion

Sample preparation is important because it makes the matrix more suitable for analysis in a number of ways: Releasing analyses from the matrix. Removing interfering elements. Concentrating the matrix if analytic levels are too low based on the detection limits of your analytical technique.

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