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Title: [Determination of eight organic residues in ion exchange resins by headspace gas chromatography].
Author: Zhu H, Zang Y, Zhang G, Lu L, Xia H.
Journal: Se Pu; 2021 Jul 08; 39(7):764-770. PubMed ID: 34227375.
Abstract:
An analytical method based on headspace gas chromatography was developed for the determination of eight organic residues in ion exchange resins, methyl isopropyl ketone, methyl butyrate, 3-pentanone, 1,3-diethyl benzene, 1,4-diethyl benzene, dichloroethane, 1,3-dichlorobenzene, and methyl methacrylate. The organic residues in different types of resins were studied to provide a basis for the safe use of ion-exchange resins in food and medicine. The main factors (chromatographic column, equilibrium temperature, equilibrium time, flow rate, etc.) that affect the accuracy and sensitivity of the eight organic residues were investigated during instrument analysis. The extraction solvent and chromatographic conditions for the samples were optimized. According to the extraction efficiencies of methyl benzene, methyl alcohol and dimethyl sulfoxide, 2.0 g of the sample was extracted with dimethyl sulfoxide under ultrasonic conditions at 20 ℃. A DB-23 chromatographic column (60 m×0.32 mm×0.25 μm) and hydrogen flame ionization detector (FID) were selected for the GC method, and good separation and quantitative results were obtained for the eight organic residues. The process and conditions are summarized as follows. The equilibration time of the headspace sampler was 30 min, and the equilibrium temperature was 80 ℃. The temperature of the sampler was 240 ℃, while that of the FID detector was 300 ℃, with nitrogen being used as the carrier gas. The programmed temperature of the column was maintained at 60 ℃ for 16 min, then increased to 200 ℃ at a heating rate of 20 ℃/min, and maintained at this level for 2 min. The flow rate was 1.2 mL/min for detection. The external standard method was utilized for quantitative analysis. Good linear relationships were observed for the eight organic residues, and the correlation coefficients (R²) were all above 0.999 in the mass concentration range of 0.02-200 mg/L. The limits of detection (LODs) were 0.0050-0.0375 ng/g. The average recoveries for the eight organic residues were in the range of 82.3% to 109.2% at three spiked levels, and the relative standard deviation (RSD, n=6) was 1.06% to 4.16%. Eleven types of resin samples were detected by this method, and a certain amount of organic compounds were observed in the resin samples. The methyl methacrylate content in the methacrylate resin XAD761 was 414.4 μg/g, while that in the styrene resin LX-69B was as high as 470.8 μg/g. As opposed to traditional analytical methods, the present method has high sensitivity, good accuracy, and precision, with simple operation without derivatization or the need for acid-base treatment of the sample to reduce contamination. This method can be used to simultaneously detect a variety of organic residues in ion-exchange resins, so that the detection efficiency is significantly improved. 建立了功能食品加工用离子交换树脂中甲基异丙基甲酮、丁酸甲酯、3-戊酮、1,3-二乙基苯、1,4-二乙基苯、1,2-二氯乙烷、间二氯苯、甲基丙烯酸甲酯8种有机残留物的顶空气相色谱检测方法,研究了不同类型树脂中的有机残留物种类及含量,为食品和药品中安全使用离子交换树脂提供依据。优化了样品的提取溶剂和顶空气相色谱条件,样品经二甲亚砜超声萃取,应用DB-23色谱柱(60 m×0.32 mm×0.25 μm)分离,氢火焰离子化检测器(FID)检测,在顶空进样器平衡时间为30 min、平衡温度为80 ℃时有机残留物的分离和定量分析效果较好。色谱条件如下:柱温采用程序升温,初始温度60 ℃,保持16 min,再以20 ℃/min的升温速率升至200 ℃,保持2 min;进样口温度240 ℃, FID温度为300 ℃ ;载气为氮气,流速为1.2 mL/min;外标法定量。结果表明,在所考察的浓度范围0.02~200 mg/L内,8种有机物的线性关系良好,相关系数(R²)均在0.999以上,检出限为0.0050~0.0375 ng/g, 3个添加水平下的平均回收率为82.3%~109.2%,相对标准偏差为1.06%~4.16%(RSD, n=6)。用所建立的方法检测11种树脂样品,结果表明,树脂样品中均存在一定量的有机物,个别产品的残留量较高,其中苯乙烯类树脂Seplite LX-69B中甲基丙烯酸甲酯残留量达到470.8 μg/g。该方法不需要衍生,简化了样品前处理过程,操作简单,准确度和精密度良好,可同时检测离子交换树脂中多种有机残留物,能显著提高离子交换树脂中有机物的检测速率,该方法的建立对我国进出口离子交换树脂中有机残留物检验工作的开展具有重要意义。

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