Direct Analysis of Metallic Elements in Cell Culture Medium by Atomic Absorption Spectrophotometry (AAS)

Introduction

The active pharmaceutical ingredients (API) of antibody drugs are mainly produced by culturing CHO (Chinese hamster ovary) cells. In recent years, it has been reported the cellular metabolism and the primary structure of the antibodies produced in a culture medium are influenced by the nutrient composition (sugars, amino acids, etc.) and the metallic element concentration of the medium. For example, where metallic elements in the culture medium are concerned, it has been noted that zinc (Zn) acts a cofactor for at least 300 types of enzymes and transcription factors when absorbed into cells (1), and the constituent sugars of glycans attached to IgG antibodies change depending on the Mn/Zn ratio in the culture medium (2). Therefore, monitoring the concentrations of metallic elements in the culture medium is considered critical for maintaining uniform quality in antibody drugs. Until now, the ICP-MS and chelate determination techniques had been used in measurements of the metallic elements in the culture media. However, ICP-MS has high initial/running costs, and the complexity of the chelate determination method is a problem, as chelate determination requires sample pretreatment for each element in order to coordinate chelating agents (chelators) with high specificity for the target elements. Therefore, we measured the metallic elements in the culture media by atomic absorption spectrophotometry (AAS), which enables inexpensive and simple analysis of metallic elements. The content of this experiment is introduced in the following.

October 1, 2020 GMT