Carbon Isotope Analysis of Individual Amino Acids in Freshwater and Marine Mammalian Hairs Based on High‐Performance Liquid Chromatography Separation and Purification: Implications for Aquatic Food Consumption in Archaeological Contexts

Compound‐specific stable isotope analysis (CSIA) has been widely applied to modern and archaeological samples of animal and human body tissues to evaluate food habits and/or physiological conditions. However, these techniques have rarely been applied to aquatic mammals, for which further study is required to evaluate their utility. This study conducted compound‐specific carbon isotope analysis of several individual amino acids using high‐performance liquid chromatography for separation and purification. This approach was applied to hair samples from two aquatic mammal species, including an archived stuffed specimen, to infer the nutritional sources in their aquatic environments, demonstrating its potential for use with diverse specimen types.