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    气相色谱-四极杆飞行时间质谱法快速测定甘油二酯油中氯丙醇酯和缩水甘油酯的含量

    Rapid Determination of Chloropropanol Ester and Glycidyl Ester in Diacylglycerol Oil by Gas Chromatography-Quadrupole Time-of-Flight Mass Spectrometry

    • 摘要: 取0.1 g甘油二酯油样品置于2.5 mL离心管中,加入100 μL 2.0 mg·L−1混合内标溶液,涡旋混匀。加入100 μL甲苯和200 μL甲基叔丁基醚,混匀后于10 ℃冷却5 min,加入200 μL含0.35 mol·L−1氢氧化钠的甲醇溶液,涡旋30 s,于10 ℃静置12 min,加入700 μL酸化溴化钠溶液,涡旋30 s,于室温静置5 min。加入600 μL异辛烷,涡旋2 min,离心5 min,弃去异辛烷层,重复净化1次,收集下层水相。加入100 μL 120 g·L−1苯基硼酸溶液,涡旋2 min,加入100 μL 1%(体积分数)乙二醇溶液和1 mL异辛烷,涡旋1 min,离心5 min,取上清液经无水硫酸钠脱水,过0.22 μm有机相滤膜,采用气相色谱-四极杆飞行时间质谱法测定滤液中2种氯丙醇酯3-氯-1,2-丙二醇酯(3-MCPDE)、2-氯-1,3-丙二醇酯和缩水甘油酯(GE)的含量。3种目标物在DB-5ms石英毛细管色谱柱上按照柱升温程序分离,采用电子轰击离子源检测,同位素内标法定量。结果表明,3种目标物的质量浓度均在0.100~2.00 mg·L−1内与其内标质量浓度的比值和对应的峰面积与内标峰面积的比值呈线性关系,检出限(3S/N)均为0.06 mg·kg−1。按照标准加入法进行回收试验,回收率为80.8%~97.6%,测定值的相对标准偏差(n=6)均小于10%。方法用于分析20份甘油二酯油样品,在1份油菜籽甘油二酯油中检出3-MCPDE和GE,检出量分别为0.335,0.408 mg·kg−1

       

      Abstract: The diacylglycerol oil sample (0.1 g) was taken and placed in a 2.5 mL-centrifuge tube, and 100 μL of 2.0 mg·L−1 mixed internal standard solution was added. The mixture was vortexed to homogeneity, and 100 μL of toluene and 200 μL of methyl tert-butyl ether were added. After mixing, the mixture was cooled at 10 ℃ for 5 min, and 200 μL of methanol solution containing 0.35 mol·L−1 sodium hydroxide was added. The mixture was vortexed for 30 s, and then settled at 10 ℃ for 12 min. 700 μL of acidified sodium bromide solution was added, and the mixture was vortexed for 30 s and settled at room temperature for 5 min. 600 μL of isooctane was added, and the mixture was vortexed for 2 min and centrifuged for 5 min. The isooctane layer was discarded, and the purification process was repeated once, and the lower aqueous phase was collected. 100 μL of 120 g·L−1 phenylboronic acid solution was added, and the mixture was vortexed for 2 min, followed by the addition of 100 μL of 1% (volume fraction) ethylene glycol solution and 1 mL of isooctane. The mixture was vortexed for 1 min and centrifuged for 5 min, and the upper solution was taken, dehydrated with anhydrous sodium sulfate, and then filtered through a 0.22 μm organic phase filter membrane. The 2 chloropropanol esters, including 3-chloro-1,2-propanediol ester (3-MCPDE) and 2-chloro-1,3-propanediol ester, and glycidyl ester (GE) in the filtrate were determined by gas chromatography-quadrupole time-of-flight mass spectrometry. The 3 targets were separated on DB-5ms quartz capillary chromatographic column by programmed column temperature, ionized by electron impact ion source, and quantified by isotope internal standard method. As shown by the results, linear relationships between the ratios of the corresponding peak area to the internal standard peak area and the ratios of mass concentrations of 3 targets to their internal standards were found in the range of 0.100‒2.00 mg·L−1, with the same detection limits (3S/N) of 0.06 mg·kg−1. Test for recovery was made by the standard addition method, giving results in the range of 80.8%‒97.6%, with RSDs (n=6) of the determined values less than 10%. This method was applied to the analysis of 20 diacylglycerol oil samples, and 3-MCPDE and GE were detected in one rapeseed diacylglycerol oil sample, with the detection amounts of 0.335, 0.408 mg·kg−1, respectively.

       

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