Development and Validation of a High-Performance Liquid Chromatography Method for the Determination of Astaxanthin in Fish Samples; Application of the Method in Identification of Fake Salmon Marketed in Iran

Astaxanthin is a carotenoid produced by different microalgae, bacteria, and yeasts in fish samples. Some fishes like salmon contain astaxanthin in their muscles and it can be a proper indicator for the identification of fishes. In this work, a simple and validated ultrasonic-assisted liquid-liquid extraction coupled to high-performance liquid chromatography-ultraviolet detector was developed for the determination of astaxanthin in fish samples in order to identify the trout from colored salmon sold in Iranian fish markets. Under the optimum conditions, analytical features of the method include a limit of detection (1.46 ng g^-1) and quantification (5.46 ng g^-1), linearity (r² = 0.995), precision (RSD < 5.2%), accuracy (RSD < 8%), and recovery (90%) were acceptable. The method was successfully used to determine the target analyte in several fish samples including thirty salmon produced in Iran, five salmon produced in Norway, and five trout samples. The results showed that trout samples were free of astaxanthin, while salmon samples produced in Iran have astaxanthin in the range of 179 ± 9-782 ± 40 ng g^-1. The content of astaxanthin in Norwegian salmons is much higher than in salmon samples produced in Iran.