Metal ions (Zn2+ and Fe3+) are transferred from water into vegetable and marine oils when these oils contain phospholipids. Ions present in the oil may be exchanged with the same or with other kinds of cations in a water phase in contact with the oils. Radioactive isotopes of zinc and iron were used for measuring the exchange rate. The sequestering action by the oil strongly depends on the contents of phospholipids and reaches a maximum (ions v/s phospholipids) in the concentration range between 3 and 60 ppm of phospholipids (0.1–2 ppm of phosphorus) in the oil. The same sequestering effect is demonstrated when purified phospholipids (phosphoethanolamine and acetone‐refined soybean lecithin) are added to edible oils from which the natural content of phospholipids has been removed. Free fatty acids do not appear to sequester multivalent ions nor to influence the sequestering action by the phospholipids when added to the oil.
A new technique is reported in which components in complex samples are separated on thin-layer chromatography plates and their mutagenic effect is registered directly on the plates by means of the Salmonella assay. The method is quick and simple and particularly useful for screening large numbers of environmental samples. Qualitative comparisons of mutagens in different samples can easily be made. REgistered mutagens can be identified by the chemical analysis of extracts from duplicate plates.
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