Stability of excise duty components

Project title: Studying the stability of selected azo and diazo compounds used as excise duty components under the influence of controlled factors

Project no.: 2014/13/B/ST4/05007

Funding source: National Science Center, Poland

Received funding: 768,174 PLN

Project duration: February, 2015 - April, 2018 (36 months)

Project members and their role in the project:

• Michał Daszykowski, Dr.Sc., Assoc. Prof. (principal investigator); University of Silesia in Katowice, Institute of Chemistry, Katowice, Poland

• Piotr Młynarz, Dr.Sc. Assoc. Prof. (key investigator); Wrocław University of Technology, Faculty of Chemistry

• Ivana Stanimirova-Daszykowska, PhD, (key investigator); University of Silesia in Katowice, Institute of Chemistry, Katowice, Poland

• Joanna Orzeł, PhD, Postdoc, University of Silesia in Katowice, Institute of Chemistry, Katowice, Poland (full time position, 33 months)

• PhD student (scholarship support, 12 months)

Research project objectives/research hypothesis: The EU countries apply different tax levels for diesel oil due to economic reasons. That is why diesel oil is deliberately spiked with excise duty components (usually compounds with azo or diazo grup) in order to indicate possible usage. To avoid illegal profit encouraged by the differences in tax levels, concentrations of these duty components are strictly controlled and regulated by the EU and local legal authorities. Even though these duty components are believed to be stable under expected conditions and are difficult to remove, there is an illegal practice of removing these components and rebated excise tax diesel oil is distributed on market. Removing the excise duty components is a violation of law, and their decreased levels can be regarded as an attempt of an illegal practice. In the course of our earlier research, we have observed that certain factors seem to influence the concentration of excise duty components. To the best of our knowledge, there are no systematic and statistically validated studies described in the literature that deal with the stability issue. This is the reason to focus our research activities on designing and conducting a comprehensive experiment in order to come to statistically sound conclusions about the stability of selected excise duty components used in Poland. We intend to investigate the influence of a few controlled factors, e.g. temperature, storage conditions and storage time and to examine the products obtained from excise duty components under the influential factors using spectroscopic sample characterization by UV-VIS, fluorescence spectroscopy, mass spectrometry and proton nuclear magnetic resonance spectroscopy. In addition, chemical changes due to fotochemical reactions will be considered for model and real fuel samples.

Research project methodology: We intend to design a comprehensive two-part experiment using principles of experimental design and chemometric multivariate analysis. Model samples are going to be spiked with excise duty components and investigated under controlled experimental factors. The concentration changes of these components will be determined using a reference method adopted in accreditated laboratories (DIN 51426-2b and 3b). Spectroscopic techniques, such as UV-VIS, fluorescence, proton magnetic resonance spectroscopy and mass spectrometry will be adopted to describe possible chemical changes undergoing in the model samples. The first part of the research work is related to screening and determining the factors that have a significant influence on the concentrations of excise duty components. Four factors will be considered in this experiment, e.g. temperature, storage conditions, influence of light and storage time that will require the use of full factorial design on two levels (2³). Once the significant factors are identified (in statistical sense), if any exist, a time-course experiment is going to be carried out in the second part of this research work. The aim of this experiment is to study the trajectory of possible changes in the model samples in detail by exploring and interpreting different spectroscopic information (different spectra) collected at each time point. Conduction of such a comprehensive time-course experiment will require the use of advanced chemometric methods to analyze the multivariate data and to identify characteristic spectral patterns. Parallel factor analysis (PARAFAC), multivariate curve resolution-alternating least squares (MCR-ALS) and its weighted version (MCR-WALS) including measurement uncertainty information in the model construction are highly valued for this purpose. The latter two methods help in exploring the process and in obtaining spectral profiles characteristic for the key steps of chemical changes observed over time. MS and NMR signals are going to be interpreted by external experts.

Expected impact of the research project on the development of science, civilization and society: The experimental work and the analysis of the collected data will help in better understanding the stability nature of excise duty components. The results of this project can point out possible directions of new research focused on the design of new potential excise duty components and provide a better protection of a product by certain authorities. In our opinion, the knowledge about the influence of the selected three factors on the stability of excise duty components is a sufficient motivation to improve protocols of sample collection and laboratory treatment. One can eventually expect that the modifications will decrease uncertainty and reduce the probability of taking a false decision (based on imprecise laboratory results due to the stability issue) by legal authorities. Moreover, we pursue the chemometric approach to explore and model complex analytical data obtained in the time-course experiment in a hope that it will gain popularity.

Available resources and planned instrumentation to carry out experiments withing the project scope:

• fluorescence spectrophotometer (Varian, Cary Eclipse) extended with multicell microplate reader, external fluorescence probe and multicuvette temperature controlled accessory with electromagnetic stirring

• multi-cuvette spectrophotometer (190-1100 nm) extended with temperature controlled accessory, smart sipper and flow cell, specular reflectance accessory, integrating sphere and integrated fiber optics module

• two climatic chambers enabling temperature and UV-light exposure control

• mass spectrometer (Varian, MS-500)

• proton magnetic resonance spectroscopy (Bruker Avance 400 MHz)