Determination of Salicylic Acid in Grapefruit Fruits Treated with Carboxymethyl Chitosan and Salicylic Acid by HPLC

In the present study, the grapefruit fruits were used as experimental materials, and the salicylic acid was extracted from the peels by trichloroacetic acid/ether, trichloroacetic acid/chloroform and ethyl acetate/cyclohexane, which was determined through high performance liquid chromatography（HPLC）, aiming to screen the optimal extraction and determination methods for salicylic acid in grapefruit peels. The method was further applied to determine the endogenous salicylic acid contents after single and compound treatments by carboxymethyl chitosan（CMC） of 15 g/L and salicylic acid（SA） of 200 mg/L. Results showed that, the superior separation effect for salicylic acid was trichloroacetic acid/ether extraction, and the optimal chromatographic conditions were determined as follows:column of Eclipse XDB-C18（150 mm ×4.6 mm, 5 μm）, mobile phase of 0.2 mol/L sodium acetate buffer solutionmethanol（40∶60） with p H of 5.5, detection wavelength of 296 nm, flow rate of 0.8 m L/min and injection volume of5 μL. SA concentrations showed a good linear relationship in the range of 3.91～500 μg/mL, the free and combined salicylic acid contents of grapefruit peels ranged from 18 ～47.6 μg/g and 68.05 ～273.85 μg/g, respectively. During28 days storage period, compared with the control, the free and bound SA contents in treated fruits showed an increasing trend, and the free SA content after CMC/SA combined treatments was significantly increased compared with that of single treatment. The trichloroacetic acid/ether extraction for salicylic acid from grapefruit peels showed a higher separation degree, and HPLC method obtained in this experiment was simple and feasible, and could be used for the extraction, separation and determination of endogenous salicylic acid from grapefruit peels.