Amperometric simultaneous sensing system for d-glucose and l-lactate based on enzyme-modified bilayer electrodes

An amperometric biosensor system which uses screen-printed electrodes to simultaneously detect d-glucose and l-lactate has been developed and applied for simple and rapid determination of d-glucose and l-lactate levels in lactic fermenting beverages. The system was constructed from three-dimensionally layered electrodes. Taking into consideration the effects of easily oxidized substances contained in the samples, ferricyanide ions, which are electrochemically oxidized at a lower voltage, were chosen as a mediator. A linear relationship between steady-state current and concentration was found over a range of 1-100 mM (d-glucose) and 1-50 mM (l-lactate); the variation coefficients were 1.43% (n = 10) and 3.50% (n = 10) for the d-glucose and l-lactate sensors, respectively. When applied to lactic fermenting beverages, there was good agreement between the results obtained by the proposed sensing system and those obtained by the HPLC method. Using the proposed method, assays were completed within 5 min.     

Monascin and Ankaflavin of Monascus purpureus Prevent Alcoholic Liver Disease through Regulating AMPK-Mediated Lipid Metabolism and Enhancing Both Anti-Inflammatory and Anti-Oxidative Systems

Alcohol metabolism causes an excessive accumulation of liver lipids and inflammation, resulting in liver damage. The yellow pigments monascin (MS) and ankaflavin (AK) of Monascus purpureus-fermented rice were proven to regulate ethanol-induced damage in HepG2 cells, but the complete anti-inflammatory and anti-fatty liver mechanisms in the animal model are still unclear. This study explored the roles of MS and AK in improving alcoholic liver injury. MS and AK were simultaneously fed to evaluate their effects and mechanisms in C57BL/6J mice fed the Lieber–DeCarli liquid alcohol diet for 6 weeks. The results indicated that MS and AK significantly reduced the serum aspartate aminotransferase and alanine aminotransferase activity, as well as the total liver cholesterol and triglyceride levels. The histopathological results indicated that MS and AK prevented lipid accumulation in the liver. MS and AK effectively enhanced the activity of antioxidant enzymes and reduced the degree of lipid peroxidation; AK was particularly effective and exhibited a superior preventive effect against alcoholic liver injury and fatty liver. In addition to inhibiting the phosphorylation of the MAPK family, MS and AK directly reduced TNF-α, IL-6, and IL-1β levels, thereby reducing NF-κB and its downstream iNOS and COX-2 expressions, as well as increasing PPAR-γ, Nrf-2, and HO-1 expressions to prevent liver damage. MS and AK also directly reduced TNF-α, IL-6, and IL-1β expression, thereby reducing the production of NF-κB and its downstream iNOS and COX-2, and increasing PPAR-γ, Nrf-2, and HO-1 expressions, preventing alcohol damage to the liver.     

高效液相色谱法测定果汁饮料中的维生素C含量

建立饮料中维生素C含量的高效液相色谱检测方法。采用ODS C18(4.6mm×250mm,5μm)反相色谱柱,以0.1%草酸溶液为流动相,光电二级管阵列检测器,检测波长为267nm。线性范围为20～160μg/mL,相关系数为0.9983,方法的回收率为96.4%～100.2%,相对标准偏差为0.61%。该方法简便、分析速度快,能够满足果汁饮料中维生素C的检测要求。     

联苯类对映体在直链淀粉类手性固定相上的高效液相色谱法直接拆分

 涂敷直链淀粉 三 (3,5 二甲基苯基氨基甲酸酯 )于自制的球形氨丙基硅胶上 ,制备了手性固定相。用该固定相直接拆分了一系列外消旋联苯类保肝药物 ,考察了一系列伯醇 (乙醇、正丙醇、正丁醇 )和异丙醇等流动相改性剂对保留和立体选择性的影响 ,讨论了固定相对样品的作用机理。     

毛细管色谱／质谱选择离子监测法测定酒精饮料中氨基甲酸乙酯

氨基甲酸乙酯是一种致癌物质,已在多种葡萄酒中被检测到。测定时,一般取样40mL,用二氯甲烷萃取,然后蒸发至近干。残留物用乙酸乙酯溶解,定容至5.0mL。取1μL进气相色谱-质谱仪（GC-MS）分析,用选择离子监测m/z62定量。CV为4.1％,其平均回收率高于80％。对8种样品的分析结果表明,氨基甲酸乙酯含量为1.01～1.78μmmol/L,与有关文献报道相近。     

高效液相色谱法同时测定功能饮料中烟酰胺、咖啡因、维生素B_6、柠檬黄、胭脂红和苯甲酸的含量

建立了一种同时快速检测功能饮料中烟酰胺、咖啡因、维生素B_6、柠檬黄、胭脂红和苯甲酸6种食品添加剂的高效液相色谱方法。6种食品添加剂的检出限分别为烟酰胺0.1 mg/L,咖啡因0.1 mg/L,维生素B6 0.2 mg/L,柠檬黄0.2 mg/L,胭脂红0.1 mg/L,苯甲酸0.1 mg/L,测定结果的相对标准偏差不大于4.57%(n=6),加标回收率在95.80%~113.68%之间。该方法满足GB/T 5009.197–2003,GB/T 23495–2009和SN/T 2105–2008对于上述6种食品添加剂检出限的要求。     

功能食品与饮品中牛磺酸的柱前衍生-高效毛细管电泳法快速测定

建立了功能食品和饮品中牛磺酸的高效毛细管电泳快速分析方法。以邻苯二甲醛(OPA)为衍生剂进行柱前衍生,采用45 mmol/L(pH9.5)的硼砂缓冲溶液为运行缓冲溶液,熔融石英毛细管(50 cm×50μm,有效长度41 cm,未涂层)为分离柱;柱上紫外检测波长:335 nm,分离电压19 kV,电泳温度20℃,重力进样,进样时间10 s。牛磺酸的质量浓度在5.0~100.0 mg/L范围内呈良好线性关系(r0.999),检出限(S/N=3)为1.6 mg/L,迁移时间和峰面积的相对标准偏差(n=7)分别为2.4%和3.8%。用该法测定了功能食品、乳制饮品和饮料等样品中的牛磺酸,相对标准偏差为0.7%~3.7%,加标回收率为93%~111%。     

基于改进标准加入法的碳酸饮料中防腐剂和甜味剂高通量筛查分析

利用正交设计分别配制含有三种防腐剂、四种甜味剂的模拟水样,采用核独立成分分析（KICA）处理模拟水样与加入不同含量标准品的饮料样品的紫外光谱(UV)数据,得到其中待测添加剂或背景成分的UV轮廓的独立组分(IC)信息,以IC的系数矩阵进行支持向量回归（SVR）分析,建立模拟样品中防腐剂与甜味剂的UV-KICA-SVR预测模型。添加不同含量水平添加剂的碳酸饮料样品,采用KICA处理其测试得到的UV光谱数据,得到与添加剂对应的IC信息及量,加入量与预测量线性回归方程截距即为饮料中添加剂含量。利用化学计量学“盲源信号分离”方法提取饮料样品中的待测添加剂IC信息与样品基质信息,利用SVR对解析得到的IC信号回归分析建模,改进传统单一组分测定的标准加入法,建立了碳酸饮料样品中防腐剂和甜味剂高通量筛查分析的新方法。方法用于测定碳酸饮料中山梨酸钾,苯甲酸钠、对羟基苯甲酸甲酯钠三种防腐剂与糖精钠、安赛蜜,阿斯巴甜和甘草酸铵四种甜味剂含量,检测限(LOD)为0.2～1.0 mg·L-1,测定结果与传统的色谱方法相当。     

Silicon-29 NMR Study of Alkaline Aqueous and Alcoholic Tri-butylmethyl Ammonium (TBMA) Silicate Solutions

Silicon-29 NMR spectroscopy was used to characterize aqueous and alcoholic alkaline solutions of tri-butylmethyl ammonium (TBMA) silicates. The effect of TBMA cation on the equilibrium of silicate oligomers in aqueous alkaline silicate solutions was investigated using ²⁹Si NMR spectra. It was found that TBMA cation has a structure directing role and directs the silicate species to form minor amounts of silicate anion in the presence of high concentration of silicon. Silicon-29 NMR spectra of TBMA silicate solutions indicate that considerable changes occurred by changing the Si/TBMA ratio. The distribution of silicate species was affected by the presence of the alcohols, specifically methanol.