The current study investigated and determined the major compounds of six essential oils derived from different plant species cultivated in Greece (Lavandula angustifolia, Origanum vulgare, Pistacia lentiscus var. chia, Citrus reticulata, Citrus limon and Crithmum maritimum). The results proved that all these essential oils have a high potential for use as food preservatives, since among the compounds determined were sabinene, b-myrcene, a-pinene, carvacrol and limonene, all of which were responsible for the strong antimicrobial activity against Staphylococcus aureus. However, the amounts of some compounds, such as linalool and citral, were at high levels, and this can be a danger for some sensitive population groups due to allergic reactions. The essential oil compounds which were identified using GC-MS and quantified through GC-FID represented more than 95% of the total essential oils of the investigated plant species. Finally, all essential oils provided high phenolic content.

A collision/reaction cell ICP-MS was used to develop a method for the multi-element determination of Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Nb, Mo, Ag, Cd, Sb, Cs, Ba, Hg and Pb in mastic gum. Evaluation of helium and hydrogen as cell gases took place and their ability to reduce several types of interference arising from a Si, S, P, C, Cl and F based matrix was investigated. Likewise, much polyatomic interference was attenuated efficiently by the effect of kinetic energy discrimination. Moreover, a study of stopping curve measurements was performed. Thus, measurements of the ion loss caused by collisions, reaction cross-sections given by the Langevin–Gioumousis–Stevenson model and collision cross-sections were carried out. The method was validated and the calculated recoveries for all elements (at three concentration levels) were ranged between 92.6% (Ti) and 105% (Ag) and the relative standard deviation (%RSD) of reproducibility was ranged between 1.6% (Co) and 9.9% (Ca). The limits of detection ranged between 0.11 ng g⁻¹ (Cs) and 1.12 μg g⁻¹ (Ca). The trueness of the method was also checked by the analysis of a standard reference material (SRM, 1573a tomato leaves).

A rapid, precise and accurate method for the determination of vitamin E (α-tocopherol) in cereal products and biscuits has been developed. The uncertainty was calculated for the first time, and the methods were performed for different cereal products and biscuits, characterized as “superfoods”. The limits of detection and quantification were calculated. The accuracy and precision were estimated using the certified reference material FAPAS T10112QC, and the determined values were in good accordance with the certified values. The health claims according to the daily reference values for vitamin E were calculated, and the results proved that the majority of the samples examined showed a percentage daily value higher than 15%.

A simple method for the determination of caffeine in coffee grains by GC-FID (Gas Chromatography-Flame Ionisation Detector) is presented in the current work. The method was fully validated according to ISO (International Organization for Standardization) 17025 requirements and European Commission regulations. The accuracy, as provided by recovery experiments, was higher than 93%, and the precision, as provided by the (%) relative standard deviation under reproducibility conditions, was lower than 5%. A vast number of independent parameters that lead in the increase of uncertainty of methods were investigated. The analysis was performed without use of an internal standard, which was proven to be reliable according to several validation methods. The method was applied in real samples, and possible health claims were investigated.