Determination of total free amino acids in Sipunculus nudus by UV spectrophotometryHongli Ye, Youqiong Cai, Longfei Zhang, Wei Yu, Yongfu Shi and Liangliang TianE3S Web Conf., 189 (2020) 02013DOI: https://doi.org/10.1051/e3sconf/202018902013