3.5 Adsorption Selectivity of the Molecularly Impr...
In order to evaluate the adsorption selectivity of the cordycepin molecularly imprinted polymer，selective adsorption experiments performed in methanol that containing 20μg/mL cordycepin or its structural analogs(adenosine and adenine).The adsorption capacity of these compounds on the cordycepin molecularly imprinted polymer or nonimprinted polymer was investigated by the equilibrium adsorption measurements.The selectivity of the cordycepin molecularly imprinted polymer was evaluated using the static distribution coefficient KD.
where CP is the concentration of substrate combined by polymer(mg/g)，Cs is the equilibrium concentration of the substrate(mg/L)，a is the imprinting efficiency，b is the selective factor，and i and j represent cordycepin and the analogs，respectively.The results are shown in Table 1.
Table 1 Adsorption of substrates on molecularly imprinted and nonimprinted polymers
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a NMIP：nonimprinted polymer.
The adsorption of cordycepin，adenosine，and adenine on the molecularly imprinted polymer was larger than on the nonimprinted polymer(Figure 7).Cordycepin was adsorbed to the greatest extent，whereas adenosine was adsorbed the least，demonstrating the selectivity for the analyte.The dimensions of adenine are smaller than adenosine.Consequently，adenine can enter into the cavity，and，therefore，the adsorption of adenine was higher than that of adenosine.These results indicated that the molecularly imprinted polymer possessed excellent selectivity and adsorption capacity.
Figure 7 Adsorption of cordycepin，adenosine and adenine