Preparation process of low-impurity compound amino acid injection

The invention provides a preparation process of a low-impurity compound amino acid injection, and belongs to the technical field of liquid medicine preparation. The preparation process provided by the invention comprises the following steps: (1) carrying out nitrogen purging treatment; (2) adding water for injection at 45-50 DEG C, and filling nitrogen; (3) adding sodium hydrogen sulfite, sequentially adding isoleucine, leucine, lysine acetate, methionine, phenylalanine and tryptophan accounting for 1/3 of the prescription dosage, and adjusting the pH value to 5.5-6.0; (4) adding sodium metabiphosphate, sequentially adding threonine, valine, alanine, arginine, aspartic acid, histidine, proline, serine, tyrosine, glycine, L-cysteine and tryptophan accounting for 2/3 of the prescription dosage, and adjusting the pH value to 6.2-6.6; (5) fixing the volume by using water for injection at 40-45 DEG C; (6) vacuumizing, filling nitrogen, filtering and filling; and (7) vacuumizing, packaging and sterilizing. The amin