超声辅助分散液液微萃取-柱切换离子色谱法测定食用油中胆碱的含量

Determination of Choline in Edible Oil by Column-Switching Ion Chromatography Couped with Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction

移取食用油样品5.00mL,加入3mol·L^(-1) HCl溶液100μL,在60℃下进行水解反应100min,将水解后的样品溶液在80℃水浴中进行超声辅助分散液液微萃取6min,乳浊液形成后以10 000转·min^(-1)转速离心10min,弃去上层油相,吸取下层水相,用0.45μm滤膜过滤,然后进行柱切换离子色谱分析,以Dionex IonPac CS12A阳离子交换色谱柱(250mm×4mm)及Dionex IonPac CG12A阳离子保护柱(50mm×4mm)为分离柱,以12mmol·L^(-1)甲烷磺酸溶液作为淋洗液,抑制型电导检测器检测。大豆油、花生油和亚麻籽油中胆碱的质量浓度均在0.02～2.50mg·L^(-1)内与对应的峰面积呈线性关系,检出限(3S/N)在1.58～1.99μg·L^(-1)之间。方法用于测定大豆油、花生油和亚麻籽油中的胆碱,测定值的日内和日间相对标准偏差(n=5)均小于7.0%,加标回收率在72.0%～98.0%之间。

100 μL of 3 mol·L^-1 HCl solution was added into 5.00 mL of edible oil sample for hydrolysis at 60 ℃ for 100 min, and ultrasound-assisted dispersive liquid-liquid microextraction was performed on the hydrolyzed sample for 6 min at 80 ℃ in a water bath. The emulsion was centrifuged at 10 000 r·min-1 for 10 min, the upper oil phase was discarded, the lower aqueous phase was filtered through a 0.45 μm filter membrane, and then analyzed by column-switching ion chromatography. Dionex IonPac CS12A cation exchange chromatographic column (250 mm×4 mm) and Dionex IonPac CG12A cation protection column (50 mm×4 mm) were used as separation columns, with 12 mmol·L-1 methanesulfonic acid solution as eluent, and inhibition conductivity detector was used for detection. The mass concentration of choline in soybean oil, peanut oil and linseed oil was linearly related to the corresponding peak area in the range of 0.02-2.50 mg·L-1. The detection limits (3S/N) were between 1.58-1.99 μg·L-1. The method was applied to determination of choline in soybean oil, peanut oil and linseed oil, giving relative standard deviations (n=5) of the measured values of intra-day and inter-day less than 7.0%, and values of recovery obtained by standard addition method were in the range of 72.0%-98.0%.