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Emulsified systems are characterized by an immiscible liquid dispersed in another liquid in the form of droplets. These systems can be classified according to the size of the dispersed droplets obtained in coarse emulsions (0.5–50 µm) or microemulsions (0.01–0.10 µm). These systems have several properties that make them interesting in several fields of technology, and the emulsion formed by oil droplets dispersed in an aqueous phase (O/A) is the most used in analytical determinations due to its low viscosity and organic load. This paper discusses the characteristics of emulsified systems, their obtention, stabilization, properties and use in the development of analytical methods for elemental analysis in matrices with high organic content such as oils, fatty foods and fuel matrices.

This paper reports the determination of the mineral composition of watercress (Nasturtium officinale Cruciferae, Brassicaceae), grown in soils from three cities in the Bahia State of Brazil, and in a fourth city where plants were grown in a hydroponic system. The sampling was carried out during the summer and winter. Analyses were performed with inductively coupled plasma optical emission spectrometry (ICP OES), and the accuracy was confirmed with a certified reference material of apple leaves. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) revealed different mineral compositions of the samples collected in the summer and winter. Samples collected in the summer had a higher concentration of the nutrients iron, calcium, and magnesium, and the samples collected in the winter had a higher concentration of manganese and copper. The average contents of the samples (expressed as wet weight) were 2.50 and 3.03 mg g−1 for calcium, 0.37 and 0.86 mg g−1 for magnesium, 8.68 and 10.84 µg g...