Calorimetric Study of Mesoporous SBA-15 Modified for Controlled Valproic Acid Delivery

Table 2

Adsoption of valproic acid on SBA-15 material modified with with APTES.

Sample	Amount aminopropyl group in the carrier (mol/g)^a	Valproic adsorption (wt%)^b		Elemental analysis
			Amount of 𝐶 before drug adsorption (wt%)	Amount of 𝐶 after drug adsorption (wt%)	Amount of valproic (wt%)
SBA-15-AP (1 : 25)-VA	6.37×10^−3	10.34	5.43	14.77	14.23
SBA-15-AP (1 : 15)-VA	1.74×−10^−3	17.89	7.98	21.87	20.12
SBA-15-AP (1 : 5)-VA	2.01×10^−3	21.78	9.34	24.67	23.87
SBA-15-AP (1 : 2)-VA	2.09×10^−3	24.56	9.55	26.45	24.45
SBA-15-VA	—	6.45	0.00	7.56	9.12

^aCalculated from elemental analysis, before drug adsorption.
^bCalculated from spectrometric analysis (in the state of adsorption equilibrium). The amount of valproic acid was calculated from the formula %_VA={[(𝐶₀−𝐶₁)×𝑉]/[𝑊+(𝐶₀−𝐶₁)×𝑉]}×100%, where: %_VA is amount of valproic acid; 𝐶₀ is initial concentration of valproic acid; 𝐶₁ is concentration of drug after adsorption process; 𝑉 is volume of drug solution; 𝑊 is weight of the carrier. The concentration of valproic acid was estimated spectrophotometrically.