2.2.5. High-performance liquid chromatography assay
For the assay, 1.0 g of each ointment was weighed accurately and placed in a stoppered centrifuge tube. Then 40 mL of chloroform / water (1:1) was added and the solution was shaken and then cen- trifuged (4000 rpm for 30 min, at 25 ◦C).
The portion of the lower layer was filtered with a 0.45 μm filter, and the filtrate served as the sample solution.
A calibration curve was prepared using TA that had separately been dried for 24 h at 105 ◦C.
TA was assayed using high-performance liquid chromatography (HPLC: e2695, Wa- ters). TA assay conditions were a column of Inertsil ODS-3 (4.6 mm ×250 mm, Ø5 μm), column temperature of 35 ◦C, mobile phase of water / acetonitrile = 2 / 1, and detection wavelength of 240 nm; con- ditions were tailored for TA to produce a peak at 9 min.
Fig. 1. Sensory test of TA ointments and PJ. *** p < 0.001, * p < 0.01, Tukey test ( n = 34 Mean ±SD).
Fig. 2. Light microscopy of TA ointments. (a) TA-A, (b) TA-B, and (c) TA-C.