基于多孔碳固载离子液体修饰电极的叔丁基对苯二酚的检测研究

制备了多孔碳固载离子液体纳米材料修饰玻碳电极(GCE),用于抗氧化剂叔丁基对苯二酚(TBHQ)的检测研究。不同电极上的交流阻抗结果表明,经过多孔碳固载离子液体修饰后的玻碳电极阻抗显著减小。多孔碳固载离子液体修饰后电极的氧化峰电流为41.93μA,比修饰前增大约5.5倍,说明多孔碳固载离子液体可显著提高电极的导电性,促进电极表面的电子转移,提高检测灵敏度。用时间~电流曲线测得TBHQ的线性范围为1.00~120.00μg/mL,检出限为0.16μg/mL。     

Direct amperometric determination of tert-butylhydroquinone in biodiesel

The direct amperometric determination of tert-butylhydroquinone (TBHQ) in biodiesel at an unmodified glassy carbon electrode is reported. A biodiesel aliquot was added into an electrochemical cell containing a 75% (v/v) ethanol-water solution under stirring (with final concentration of 50 mmol L⁻¹ HClO₄). The amperometric method involved the continuous application of three sequential potential pulses to the working electrode (700 mV for 300 ms, 0 mV for 100 ms and −50 mV for 1 s). TBHQ was continuously monitored at the first (direct oxidation) and optionally at the second (reduction) potential pulse while the third potential pulse was applied for cleaning of the electrode surface. For comparison, the samples were also analyzed by high-performance liquid-chromatography and a good agreement between the results was verified. Recovery values for spiked samples were between 90% and 95% and the reproducibility of the proposed method was around 5% (n = 5). The proposed method can be easily adapted for on-site analysis.     

高效液相色谱法测定叔丁基对苯二酚的含量

建立了HPLC测定叔丁基对苯二酚含量的方法:色谱柱:Shim-pack VpODS(150 mmt×4.6 mm,5μm)接C18保护柱(20 mm×4.6 mm,5μm);以V(乙腈):V(水)=32:68(含1%乙酸)作为流动相;流速:0.8 mL/min;检测波长:290 mm;柱温:25℃.结果表明TBHQ质量浓度在2×10-4～1.0 mg/mL范围内与峰面积线性关系良好r≥0.9999,最低检测限为4 ng,并建立了回收率及日内和日见精密度实验.     

Chemical composition and antioxidant activity of Borago officinalis L. leaf extract growing in Algeria

The aqueous and hydroalcoholic extracts of borage (Borago officinalis) leaves from Annaba region (Algeria) were preliminary analyzed for their phenolic profile (total phenolics, total flavonoids, total flavonols, total tannins and total anthocyanins). These extracts were evaluated for their antioxidant properties by different methods such as DPPH radical scavenging, test NBT and total antioxidant activity. The two extracts have exhibited a high antiradical capacity. Indeed, the ethanolic extract showed the lower IC50 values and the highest amount of phenolics (94.09 ± 1.72 mg gallic acid/g dry extract). Using LC-MS/MS analysis, it was possible to identify phenolic acids, flavonoids, sterol and for the first time oleuropein was identified in the aqueous extract of the plant. The obtained results have demonstrated that phenolic compounds are the major contributor to the antioxidant activity of plants.     

两种常用合成抗氧化剂的拉曼光谱研究

随着社会的不断进步,食品工业得到快速发展,随之食品安全问题也层出不穷。由于合成抗氧化剂价格较低且对食品有较好的防腐保鲜作用,常被一些食品生产商过量添加在食品中,严重危及人们身心健康。因而,对于食品中合成抗氧化剂的检测研究是十分必要的。丁基羟基茴香醚(BHA)和叔丁基对苯二酚(TBHQ)是两种常见的合成抗氧化剂。实验上, 利用共聚焦显微拉曼光谱仪分别对BHA和TBHQ进行拉曼光谱检测,获得样品的拉曼散射谱。理论上,应用密度泛函理论DFT(B3LYP)的三参数混合方法及6-31G(d, p)基组对其进行空间结构优化并计算其拉曼光谱,给出了光谱强度图。将理论结果与实验结果进行对比发现,在50～4 000 cm-1范围内BHA及TBHQ分子拉曼特征明显且拉曼活性较强,其振动频率在实验上和理论上显示出较好的一致性。另外,给出了BHA和TBHQ分子的红外活性、拉曼活性以及各频率谱线对应的振动模式归属。结果表明,BHA和TBHQ分子的拉曼频移表征物质的特征结构,可以作为鉴定和识别的检测依据。该研究报道了抗氧化剂BHA和TBHQ的拉曼光谱,并对其理论机制进行分析,为拉曼光谱技术应用于食品添加剂研究领域提供了理论和实验依据。     

高效液相色谱法测定食品中特丁基对苯二酚

用高效液相色谱法测定食品中的抗氧化剂特丁基对苯二酚。样品经甲醇提取过滤后测定,检测波长为280nm,流动相为乙腈-1%乙酸(体积比为45∶55),回收率大于85%,测定结果的相对标准偏差小于2%。     

高效液相色谱法测定油脂中抗氧化剂BHA、TBHQ

采用乙腈浸提油脂中抗氧化剂叔丁基羟基茴香醚(BHA)和特丁基对苯二酚(TBHQ)，用以乙腈-水淋洗的反相高效液相色谱法测定提取液中BHA，TBHQ，回收率为92.42％～96．69％，变异系数为2．26％～2．88％，方法简便、快速、准确，已用于油脂中抗氧化剂BHA、TBHQ的测定。     

高效液相色谱法同时测定食用油脂和膨化食品中的3种抗氧化剂

建立同时测定食用油脂和膨化食品中3种抗氧化剂丁基羟基茴香醚(BHA)、二丁基羟基甲苯(BHT)、特丁基对苯二酚(TBHQ)的高效液相色谱法.样品经甲醇提取后,以甲醇-0.1%甲酸溶液为流动相梯度洗脱,C18色谱柱分离,采用高效液相色谱法(HPLC)-二极管阵列检测器(DAD),在检测波长280 nm,参比波长360 n...