Determination of oxygen heterocyclic compounds in Citrus-flavored food and cosmetic products by means of liquid chromatographic techniques

The crucial function of analytical chemists in guaranteeing product quality and safety cannot be overstated. They are entrusted with the responsibility of safeguarding public health through meticulous analysis of food, cosmetic and pharmaceutical samples for the detection of contaminants and adulterants. Liquid chromatography (LC) and mass spectrometry (MS) represent indispensable techniques in this pursuit, offering unparalleled capabilities for the identification and quantification of diverse analytes. Moreover, in recent years, there has been a growing awareness of environmental issues, which has resulted in the implementation of sustainable practices for the development of analytical methods. Throughout my doctoral research, LC coupled with photo-diode array detector (PDA) and/or mass spectrometer (single quadrupole (Q) and triple quadrupole (QqQ)) were employed to investigate the oxygen heterocyclic composition of various food and cosmetic products. Specifically, an initial work focused on the development of a sustainable HPLC-QqQ/MS analytical method for the determination of thirty-six oxygen heterocyclic compounds (OHCs) in less than 4 minutes using only water and ethanol as mobile phases. The developed and validated method was subsequently applied to a range of matrices, including Citrus essential oils, non-alcoholic beverages and perfumes, which were injected directly into the LC system without any pre-treatment. Subsequently, research activity has been directed to the development of new eco-friendlier methods for the extraction of OHCs from complex matrices. A liquid-liquid extraction (LLE) procedure, employing only 1 mL of sample and 1 mL of ethyl acetate (EtOAc), was developed for extraction of OHCs from alcoholic beverages. A solid-liquid (SLE) technique was also optimized for the extraction of OHCs from a range of foodstuffs, including bakery products, chocolate bars, chew gums, candy and jams. The SLE procedure employed 1 g of sample and 1 mL of ethanol (EtOH) as extraction solvent. In cosmetic field, extraction from hand gels was obtained by developing an LLE procedure. In this case, taking into account the presence of ethanol in the samples, a clear phase separation was obtained only when a specific ratio of EtOH/H2O/EtOAc of 1:1.4:1.7 (v/v/v) was maintained. During the PhD period abroad at Gembloux AgroBioTech, University of Liège (Gembloux, Belgium), a microwave-assisted extraction (MAE) of OHCs from body creams was optimized and validated. To the best of the authors' knowledge, a deep eutectic solvent has been used for the first time for the MAE of OHCs from cosmetic samples. Then, the extracts were underwent solid-phase extraction (SPE) clean-up and were analysed by means of HPLC-PDA detection.