Application of cationic dye pyronin G (Y) for quantitative extraction-photometric determination of higher carboxylic acids in fish

The relevance of this study is due to the need to develop methods for the extraction and quantitative determination of higher carboxylic acids in fish. In this work, we propose a simple, inexpensive, and highly sensitive extraction-photometric technique for the selective determination of the total content of fatty acids. This technique is selective and is based on the quantitative extraction into the organic phase of ionic associates of the cationic dye pyronin G (Y) with highly hydrophobic carboxylic acids and seems promising for the quantitative determination of the fatty carboxylic acids in fish. Considerable attention is paid to the sample preparation, which is the most important stage of analysis, since the work is carried out with a natural sample that has a complex composition. The technique has been tested on real objects, also using this technique, a directly proportional dependence of the concentration of higher carboxylic acids in fish on the storage time has been obtained. It has been established that the heptane/iso-propanol system is the most effective for the extraction of higher carboxylic acids. The limit of detection of higher carboxylic acids by the extraction-photometric method using the cationic dye pyronin G(Y) in fish is 4,4 10-7 M. The results obtained allow us to state that the developed method can be used to determine the freshness of fish.