The aim of this work was to examine the potential of ATR-FTIR and Raman spectroscopies to evaluate changes happening during the development and maturation of olive fruit. To do this, the spectra of the different parts of the olive (skin, flesh and stone) have been measured at different stages of development. The evolution of different spectral bands has been related to the content of olive constituents like triglycerides, water, carotenoids and phenolic compounds. Oil accumulation can be followed using both FTIR and Raman spectroscopy. The increase in bands at 1746 cm(-1) (ATR-FTIR) and 1440 cm(-1) (Raman) correlates well with the oil content in the fruit determined using the standard Soxhlet extraction method. In the case of overripe olives ATR-FTIR does not provide a representative spectrum of the olive flesh due to the accumulation of water on the surface of the ATR crystal. The increase of the content in carotenoids and phenolic compounds during olive growing and their decrease during the ripening phase can be successfully monitored by means of the Raman bands at 1525 and 1605 cm(-1), respectively.
A flow-through sensor system with Fourier transform (FT) Raman spectroscopy as detection technique is described. The molecular and structural information contained in Raman spectra together with the selective retention of the species of interest on the sorbent make the proposed methodology highly selective. The flow-through sensor allowed the direct quantitative determination of sulfathiazole and sulfamethoxazole in the presence of other species that are normally encountered with these analytes. The system used Sephadex QAE A-25 resin as packing material of a flow-through cell on which sulfonamides were temporarily retained. Samples were transported by a carrier solution of NaOH 10(-2) mol l(-1) (pH = 12), and 2 ml of a [NaCl (0.10 mol l(-1))/NaOH (10(-2) mol l(-1))] solution was employed as eluent. Using a sample volume of 1 ml, the analytical signal was linear in the range 0.5-7 g l(-1) and 0.5-10 g l(-1), for sulfathiazole and sulfamethoxazole, respectively. RSDs (%) lower than 4% were obtained for both analytes. The sensor was satisfactorily applied to several commercial pharmaceutical preparations for human and animals in different physical presentations, including capsules, syrup, tablets, powders, injectables and suspensions.
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