Abstract:

A method for the simultaneous determination of squalene, four tocopherols and four steradienes in vegetable oils
by high-performance liquid chromatography (HPLC) coupled with UV detector and fluorescence detector was developed. The
sample was dissolved in n-hexane and cleaned up on a silica gel column. Nine analytes were first separated on a C30 column
(250 mm × 4.6 mm i.d., 5 μm) by gradient elution, at 25 ℃, with a mobile phase consisting of acetonitrile/methyl-tert-butyl
ether (70:30, V/V) and water at a flow rate of 1.0 mL/min. The wavelength of UV detection was set at 210 nm for squalene and
235 nm for steradienes, respectively. The excitation and emission wavelengths of fluorescence detection were set at 290 nm
and 340 nm for tocopherols. The method showed linear response for concentrations in the range of 0.05–100.0 mg/L
for tocopherols, 5–500 mg/L for squalene, and 0.02–1.0 mg/L for steradienes, and the correlation coefficients (γ) were
greater than 0.999. The average recovery rates of nine analytes in vegetable oils ranged from 85.5% to 103.8% at
three spiked levels of 1, 100 and 500 mg/kg for tocopherols, 10, 100 and 500 mg/kg for squalene, and 0.075, 0.15 and
0.50 mg/kg for steradienes, and the relative standard deviations (RSDs) were less than 10%. The limits of detection (LOD)
were 0.03 mg/kg for tocopherols, 3 mg/kg for squalene, and 0.012 mg/kg for steradienes. The limits of quantification (LOQ)
were 0.1 mg/kg for tocopherols, 10 mg/kg for squalene, and 0.04 mg/kg for steradienes. The proposed method is sensitive,
accurate and reliable, and has been successfully applied to real sample analysis.

Key words: squalene, tocopherols, steradienes, high-performance liquid chromatography (HPLC), vegetable oils