Determination of total free amino acids in Sipunculus nudus by UV spectrophotometry

Abstract

Here we developed a new, facile method to detect free amino acids (TFAA) in Sipunculus nudus by UV spectrophotometry. The pretreatment conditions of the approach were optimized, such as chromogenic reaction temperature and time, the measurement time after chromogenic reaction, the extraction agent and its concentration, the extraction time. The established method showed a good linearity in the TFAA range 0.0 ~ 40.0 cg/mL (R2= 0.9958) with the limit of detection (LOD) 1.96 g /mL and the precision of 6.14 % (relative standard deviation, RSD). The addition standard recoveries were 95.1 % ~108.6 %. Finally, the method was successfully applied in detection of TFAA in Sipunculus nudus and other aquatic products. The results showed that the content of TFAA in Sipunculus nudus was higher than that in the other aquatic products collected in our paper, and as high as 138.14 g/kg.