Question

Assume you work as an engineer at a pharmaceutical plant which produces therapeutic monoclonal antibodies (mAbs) from Chinese Hamster Ovary (CHO) cells. You are tasked with inoculating a 2,000 liter CHO cell reactor for mAb production. The final CHO cell concentration must reach 10 g/L before harvesting and downstream processing. Assume that the empirical chemical formula of Chinese Hamster Ovary (CHO) cells is CN0.25O0.51H2.02S0.007P0.016.
Calculate:
(a) the weight percent of phosphorus in CHO cells
(b) the amount of KH2PO4 you must add to the medium to achieve a cell density of 10 g/L

Answer 1

a) we have empirical chemical formula

= CN0.25O0.51H2.02S0.007P0.016

calculate mass of empirical formula = 12 x 1 (C) + 14 x 0.25(N) + 16 x 0.5 (O) + 1 x 2.02(H) + 32 x 0.007(S) + 31 x 0.016(P) = 26.24g

mass of P in it =  31 x 0.016 = 0.496g

% = 0.496g/26.24g x 100 = 1.89%

b) we need total 2000L

and concentration = 10 g/L

total mass of CHO = 10 g/L x 2000 L = 20000g

1.89 % is P in it

= 20000g x 1.89/100 = 378.0 g

this P mass should come from KH₂PO₄

molar mass = 136.086 g/mol

31g in 136.086 g molecule

we need 378g P KH₂PO₄ = 136.086/31 x 378 = 1659.37g

Ans = 1659.37 g KH₂PO₄ needed