Solid-phase Extraction of Valproic Acid Using a Surfaced Imprinted Silica Gel Adsorbent

Using a solid-phase extraction for the determination of VPA, this study aimed to prepare a valproic acid (VPA) imprinted silica gel adsorbent by surface molecular imprinting technique. VPA-imprinted silica adsorbent was characterized by FTIR spectroscopy. The VPA adsorption from solutions was studied in SPE mode. All influenced parameters on adsorption efficiency, including the elution concentration, MIP amount, VPA concentration, pH and salting effect, sample flow rate, column performance repeatability (relative standard deviation) were optimized independently. The prepared adsorbent showed significant adsorption capacity and selectivity for VPA. In the condition of sodium hydroxide solution (0.1 M), MIP polymer (250 mg), VPA (10-4M), sample flow rate (1 ml min-1), pH around 2-6 in the presence of 4 % NaCl, total VPA retention showed better reproducibility than 5%. Recovery of VPA was about 94.6 to 98.1% and the relative standard deviation was less than 5.69%.  These results demonstrated that the prepared adsorbent can be used to measure VPA in biological samples.