2.2.1. Extraction and GC-MS Analysis of Lemon Essential Oil (LEO)

The method of extracting essential oil referred to Guo et al. [4]. LEO was extracted from a mixture of lemon peel and water by steam distillation. Sodium chloride was added in the extraction process, and anhydrous sodium sulfate was added to dry the essential oil after extraction. The determination of LEO components was determined according to procedures reported earlier [19]. LEO was analyzed by GC–MS using an Agilent 7890A GC with a Gerstel MPS autosampler and an Agilent 5975C MSD detector. The carrier gas was helium with a flow rate of 1 mL/min. The temperature was programmed as follows: the initial temperature of 40 ◦C was maintained for 1 min; the temperature was increased to 220 ◦C at a rate of 3 ◦C/min for 25 min; the final temperature of 250 ◦C was reached at a rate of 5 ◦C/min for 10 min. MS conditions were 70 eV EI and an ion source temperature of 230 ◦C. The mass-to-charge (*m*/*z*) range was set to 35–350 atomic units. The National Institute of Standards and Technology (NIST 08) was used to compare the data of the LEO components.
