https://www.selleckchem.com/products/pri-724.html Guanosine tetraphosphate (G4P) and guanosine pentaphosphate (G5P) are signalling nucleotides found in bacteria and photosynthetic eukaryotes that are implicated in a wide-range of processes including stress acclimation, developmental transitions and growth control. Measurements of G4P/G5P levels are essential for studying the diverse roles of these nucleotides. However, G4P/G5P quantification is particularly challenging in plants and algae due to lower cellular concentrations, compartmentalization and high metabolic complexity. Despite recent advances the speed and accuracy of G4P quantification in plants and algae can still be improved. Here, we report a new approach for rapid and accurate G4P quantification which relies on the use of synthesized stable isotope-labelled as internal standards. We anticipate that this approach will accelerate research into the function of G4P signaling in plants, algae and other organisms.Currently, extra virgin olive oil, virgin olive oil and lampante olive oil are classified using physical-chemical analyses and a sensory analysis of fruitiness and defects, which is carried out by expert panels. This manual analysis is nowadays considered to be controversial and therefore analytical methodologies, which may be automated to classify these samples, are needed. In this work, we propose using an analytical platform based on two orthogonal techniques to determine the flavour components perceived in the mouth and the components contributing to the olive oils (OOs) aroma, respectively. For the former, capillary electrophoresis with ultraviolet detector (CE-UV) and high-performance liquid chromatography with UV or fluorescence detection were explored. The CE-UV analysis provided better results with the developed chemometric models (principal component analysis, linear discriminant analysis and k-nearest neighbors method). While for the latter, headspace (HS) - gas chromatography coupling wit