# Effects of Pulsed Electric Field on Oil Extraction Rate and
## Appendix A. Tocopherol Detection in Peony Seed Oil  
1. Preparation of mixed standard solution. The \(\alpha\)-tocopherol control product, \(\beta/\gamma\)-tocopherol control product and \(\delta\)-tocopherol control product were accurately weighed and placed in 25 mL brown volumetric bottle, respectively, dissolved with methanol, and fixed to the scale line. The concentration of \(\alpha\)-tocopherol control solution was 0.425 mg\(\cdot\)mL\({}^{-1}\), the concentration of \(\beta/\gamma\)-tocopherol control solution was 0.1 mg\(\cdot\)mL\({}^{-1}\), and the concentration of \(\delta\)-tocopherol control solution was 0.1 mg\(\cdot\)mL\({}^{-1}\). We precisely absorbed 0.1 mL, 0.2 mL, 0.5 mL, 1.0 mL, 2 mL and 3 mL of each reference solution into a 25 mL volumetric bottle, filled it with methanol to the scale line, and shook well as a mixed reference solution with different concentrations. 2. Preparation of test samples. The appropriate amount of peny seed oil extracted from different samples was taken, and 0.1 g was taken from each sample. As for the graduated centrifuge tube, methanol was used as the extraction agent, the ratio of solid to liquid was 1:1.2 (g/mL), ultrasonic extraction (power 250 W, frequency 40 kHz) was carried out for 30 min, and the methanol extract was extracted twice. After concentration by nitrogen blowing instrument, the volume of peny seed oil was fixed with methanol to 0.15 mL. The sample was filtrated, then the further filtrated liquid was taken, and then obtain the sample liquid to be measured. 3. Determination of samples. High performance liquid chromatography (HPLC) was performed by Agilent1260, including high pressure four-element pump (G1311A), column temperature chamber (AT-950) and diode array detector (G1315D), and Agilent ZORBAX Eclipse Plus C18 column (4.6 mm\(\times\) 250 mm, 5 \(\upmu\)m) was selected. The volume ratio of mobile phase methanol to water was 98:2, the volume flow rate was 1.0 mL\(\cdot\)min\({}^{-1}\), the column temperature was 35 \({}^{\circ}\)C, the detection wavelength of DAD detector was 295 nm, and the sample size was 20 \(\upmu\)L. All components could be separated well under the chromatographic conditions. We precisely absorbed the mixed reference solution in step (1) and the sample solution to be measured in step (2), and, respectively, injected the samples for determination according to the chromatographic conditions in step (3). The liquid chromatographic spectra of several tocopherools in the mixed reference product and the sample to be measured are shown in Figure 11.
4. Investigation of linear relationship, determination of detection limit and quantitative limit. The mixed reference solution (20 \(\upmu\)L each) prepared in step (1) was precision absorbed and injected into the liquid chromatograph. The peak areas of \(\alpha\)-tocopherol, \(\beta\)-tocopherol, \(\gamma\)-tocopherol and \(\delta\)-tocopherol were measured according to the chromatographic conditions in (3). The peak areas were repeated 3 times, and the average values were taken. The standard curve was calculated with injection concentration X as the horizontal coordinate and peak area and Y as the vertical coordinate. When the signal-to-noise ratio (S/N) is 3, the concentration of the measured substance is the limit of detection, and when the signal-to-noise ratio (S/N) is 10, the concentration of the measured substance is the limit of quantification. The results are listed in Table 11. From Table 11, it can be seen that each component has a good linear relationship within its own range. * [5] Precision test. A total of 20 \(\mu\)L of \(\alpha\)-tocopherol, \(\beta\)-tocopherol, delta-tocopherol mixed reference solution was accurately absorbed, and the samples were continuously injected for 6 times according to the chromatographic conditions in step (3). The peak area was recorded, and the RSD value of the peak area of each compound was calculated. The results are shown in Table A2. * [6] Stability test.