An earlier investigation has presented a novel procedure in the chromatographic reactor, capable of efficiently determining the enantioselectivity of the enzyme for a biocatalyzed process. In this work, a mathematical model including the effect of axial dispersion is formulated to describe the transient behavior of the fixed-bed used to evaluate the enantiomeric ratio. A valuable relationship among the enantioselectivity, Peclet number, and transient responses at the exit of reactor is also established through the theoretical analysis, In addition, a relation is proposed to evaluate the significance of axial dispersion in the fixed-bed, allowing us to apply this criterion to assess the necessity of further studying the Peclet number.