\(\text{Yield\ }\left(\%\right)=\ 61.66+0.63*Po-0.61*Po^{2}+3.17*\frac{B}{O}-0.55*\left(B/O\right)^{2}+10.68*\frac{C}{S}-3.75*\ \left(\frac{C}{S}\right)^{2}+0.55*Po*\frac{B}{O}-0.20*Po*\frac{C}{S}-2.75*\frac{B}{O}*C/S\) (5)