Qp 2010 series

Analyses of the fatty acid composition of C. elegans were done as described previously (Watts and Browse, 2002 (link)). Briefly, 200 adult C. elegans were collected with M9 buffer and washed three times. After centrifugation, M9 buffer was removed with a pipette and replaced with 1 mL 2.5% H₂SO₄ in methanol to extract fatty acids from tissues and then to carry out their transmethylation. Samples were capped and incubated for 1 h at 80°C. After the addition of 0.2 mL hexane and 1.5 mL water, fatty acid methyl esters were extracted into the hexane layer by shaking and centrifugation of the tubes at low speed. Aliquots (1 μL) of the organic phase were analyzed by GC using a gas chromatograph (QP2010 series; Shimadzu, Kyoto, Japan) equipped with a RTX-5MS column (30 × 0.25 mm). Mass conditions: EI source (70 ev), dual-filament, scanning range (50–500 m/z), scan interval 1.0 s. Helium was the carrier gas (injected at 1.4 mL/min), and a flame ionization detector was employed. The gas chromatograph was programmed at an initial temperature of 120°C for 1 min, followed by an increase of 10°C/min to 190°C, followed by an increase of 2°C/min to 200°C. The mass spectra of the peaks identified as palmitic acid, palmitoleic acid, oleic acid, and stearic acid matched the spectra presented by W. W. Christie on the lipid library website¹.

The gas chromatography–mass spectrometry (GC–MS) analysis of the methanolic plant extract of Citrus aurantifolia fruit peel was carried out using GC–MS (QP 2010 series, Shimadzu, Tokyo, Japan). For GC–MS analysis of the plant extract, an electron ionization system with ionization energy of 70 eV was used. Helium gas is used as a carrier gas at a constant flow rate of 1.51 mL/min. The injector and mass transfer line were set at a temperature of 200–240 °C. The temperature of the oven was also set between 70 and 220 °C at 10 °C/min. About 50 μL prepared sample with methanol (HPLC grade) was introduced into the injector in the split-less mode with a split ratio of 1:40 and with mass scan of 50–600 amu. The GC–MS analysis running time was set at 35 min. The relative percentage of the plant extract constituents was presented as a percentage with peak area normalization. Percentage of the extract constituents was expressed as a percentage with peak area normalization. The identification of the chemical compounds was conducted by comparing the spectrum of unknown chemical compounds with the known spectrum of the chemical compounds in the NIST structural library to identify the names, molecular weight, molecular formula, and structure.