Detection of amino thiols from fish samples by stable isotope chemical labelling coupled with ultra-performance liquid chromatography-tandem mass spectrometry

The amino thiols are key antioxidants in organisms, and their detection in food is of significant importance. This study developed a new stable isotope chemical labelling coupled with ultra-performance liquid chromatography-tandem mass spectrometry method to detect six amino thiols from fish samples. By the proposed method, amino thiols were labeled after liquid extraction using the stable isotope labeling reagents of iodoacetamide (IAM) and D 4 -IAM. Desirable recovery and linearity of thiols were achieved in fish samples. The limits of detection (LOD) ranged from 0.2 to 6.5 nmol/g, and the detection sensitivity was improved from 2.6 to 74 folds. The cluster analysis revealed that this method successfully discriminated eight fish species and their sources. Additionally, we found that glutathione and cysteine were significantly correlated with the transportation stress status of golden pompano ( Trachinotus ovatus ). Overall, this study presents a sensitive and efficient method for the detection of amino thiols from fish samples.