Table 1: Range of different factors investigated with Plackett-Burman design.

FactorsLevel
−11

(ZnSO4)0.4 mg/L1 mg/L
(transferrin)4 mg/L10 mg/L
(putrescine)0.4 mg/L1 mg/L
(BSA)80 mg/L200 mg/L
(ferric citrate)0.3 mmol/L1 mmol/L
(sodium pyruvate)0.3 mmol/L1 mmol/L
(ethanol amine)2 mg/L6 mg/L