ABSTRACT
To establish an ultra high performance liquid chromatography coupled with pre-column derivatization method for simultaneous determination of 17 kinds of free amino acid concentrations in CHO cell which expressed high levels of programmed death protein-1 (PD-1) antibody, and its amino acid metabolism was analyzed by this method. Using 6-aminoquinoline-N-hydroxysuccinimidyl carbamate (AQC) as a derivatization reagent, the free amino acids in different concentrations of amino acid standards or cell lines were transformed into stable UV-absorbent compounds, which were separated by gradient elution through ACQUITY UPLC BEH C18 (2.1 mm × 100 mm, 1.7 μm) column. The flow rate was set at 0.7 mL·min-1, the column temperature at 55 ℃, the loading amount of sample at 1 µL, the UV detection wavelength at 260 nm, and then the free amino acid concentration in cell lines which expressed PD-1 antibody was determined by external standard method. According to the changes of amino acids concentration during the process of cell culture, the amino acid metabolism was analyzed. The results showed that pre-column derivatization high performance liquid chromatography could completely separate 17 kinds of amino acids within 11 minutes, has good linear relationship (R2 ≥ 0.999 3) in the range of 0.75-500 μmol·L-1, the limits of detection was 0.1-0.3 μmol·L-1, the limits of quantitative was 0.5-1 μmol·L-1. The established method is quickly and reproducibility. Amino acid metabolism revealed that methionine, isoleucine and leucine may be the restrictive factors of expression for cell line. This method can be used for detection changes of free amino acid concentration in cell line.