High-performance liquid chromatography separation of phthalate acid esters with a MIL-53(Al)-packed column

In this study, a MIL-53(Al)-packed column was successfully prepared and firstly applied to separate phthalate acid esters (butyl benzyl phthalate, di-n-butyl phthalate, diethyl phthalate, bis(2-ethylhexyl) phthalate, and dimethyl phthalate). Their baseline separation could be achieved within 12 min with a mobile phase of methanol/H2 O ratio at 92:8, and the temperature and flow rate was 40°C and 0.6 mL/min, respectively. The stacking effect and electrostatic force were the key factors in the separation. Moreover, there was a substantial linear relation between the peak height, peak area, and the analyte mass, and the relative standard deviations of retention time, peak height, peak area, and half peak width for five replicate separations of the analytes were within the ranges 0.31-0.88%, 0.72-1.52%, 1.33-1.53%, and 0.46-0.95%, respectively. The results of the calculation of the thermodynamics parameters showed that the separation of phthalate acid esters was controlled by both enthalpy change (ΔH) and entropy change (ΔS).