近红外光谱对市售黄芩饮片中黄芩苷含量的快速测定

应用近红外光谱技术(NIR)和OPUS数据分析软件,对市售黄芩饮片中黄芩苷的含量进行了快速测定.采用偏最小二乘法(PLS)对黄芩饮片的结果与NIR建立校正模型,最小最大归一化法为黄芩苷的最优预处理建模方法,优化校正模型中真实值与预测值之间的相关系数(R2)为0.896 1,内部验证均方差(RMSECV)为0.836,最佳主因子数为9,预测平均偏差为0.92%.NIR具有非破坏性、无污染、重现性好等优点,可以用于市售黄芩饮片中黄芩苷含量的快速测定.     

A new form of vanadium oxide for use as a cathode material in lithium batteries

A new form of vanadium oxide, (Na₂O)_0.23V₂O₅, is synthesised by precipitation of sol and removing water. Its performance as a cathode material is studied by chronopotentiometry and cyclic voltammetry. A capacity of more than 220 mA h g⁻¹ can be obtained in 12 cycles when the voltage is from 3.8 to 1.8 V. Its capacity and cyclability are satisfactory in comparison with other forms of vanadium oxide and synthesis is relatively easy. X-ray diffraction (XRD) studies show that (Na₂O)_0.23V₂O₅ is quasi-tetragonal crystal after heating at a temperature below 250°C. The crystallites of (Na₂O)_0.23V₂O₅ are in platelet form, and their dimensions are less than 2 μm. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) studies found that the sol-precipitate, (Na₂O)_0.23V₂O₅·xH2O, can lose water at 200°C.     

Vinylation of phenol by acetaldehyde: A new reaction for the synthesis of o-vinylphenol

A new catalytic reaction for the single-step synthesis of o-vinylphenol from phenol and acetaldehyde in the gas phase is investigated in this work. A search for an efficient catalyst was made. The best results were obtained with a modified Cr₂O₃ catalyst supported on γ-Al₂O₃. The effect of content of Cr₂O₃ and potassium as a modifying additive was studied. It was shown that the catalyst containing 13% Cr₂O₃ and 1% K makes it possible to obtain o-vinylphenol with a selectivity of 100% referred to phenol and up to 87% referred to acetaldehyde. The influence of reaction conditions on the activity, selectivity and stability of catalyst operation was elucidated.     

肉制品中生物胺形成与控制研究进展

生物胺是一类含氮的脂肪族胺、芳香族胺或杂环类低分子有机化合物,主要通过微生物分泌的氨基酸脱羧酶作用于氨基酸产生。肉制品中生物胺降低产品质量、缩短货架期,同时,过量的生物胺对人体健康存在潜在威胁。本文综述原料肉、工艺条件、微生物等主要影响肉制品生物胺形成的因素,归纳肉制品中生物胺的相关控制措施,提出采用多种技术相结合、优势互补的方式,有助于形成肉制品中整个产业链的防控体系,切实解决肉制品行业的质量安全问题。     

2017年食品检验实验室能力验证结果分析

目的 了解在陕西省内从事食品检验活动的实验室检验能力的整体水平, 评价各食品实验室的检测能力与质量保证水平, 为实验室监管部门提供技术支撑。方法 通过设计与实施能力验证计划, 获得各参加实验室8个能力验证项目的测定结果, 对结果进行稳健统计分析, 通过Ｚ比分数评价实验室检测能力, 并对结果进行分析。结果 全省共有42家实验室参加了本次能力验证项目, 累计提交了220个结果, 其中结果满意为29家, 总体满意率为69%, 8个项目满意率分别为氨基酸态氮89.5%、糖精钠88.2%、二氧化硫84.4%、三氯杀螨醇80.0%、镉90.0%、可待因61.5%、西布曲明85.7%、沙门氏菌100%。结论 参加本次能力验证活动的实验室, 多数的检测能力评价为满意, 表明各实验室检测水平总体良好, 具有相应项目的检验能力。但仍有少数实验室评价结果不满意, 应进一步加强实验室的检测能力水平。     

Influence of noodle processing (industrial protocol) on deoxynivalenol

The effects of processing for two types of Asian noodles production (yellow alkaline and instant) on DON levels were investigated. Deoxynivalenol (DON) level at each step of processing was determined using high performance liquid chromatography (HPLC) with a PDA (photodiode array) detector at 218 nm. An acetonitrile: water (17:83 v/v) mixture was used as mobile phase and a MycosepTM #225 column as clean-up method. Significant reductions of the initial DON levels were found, 43.2% and 66.6% in yellow alkaline and instant noodles, respectively. The presence of alkaline salt as an ingredient appeared to be the primary factor influencing the extent of reduction in the two types of noodles. The data indicated that significant reduction of DON have occurred during cooking and frying of both yellow alkaline and instant noodles, respectively. The mechanism of reduction due to cooking is probably a leaching of DON out of the noodle into the cooking medium.     

Deoxynivalenol reduction during the frying process of turnover pie covers

The effect of the frying process on deoxynivalenol contamination was evaluated. Deoxynivalenol naturally contaminated flour (1200 μg/kg) and fortified flour artificially contaminated (260 μg/kg) were used to prepare turnover pie dough covers. Frying was performed at three temperatures (169 °C, 205 °C and 243 °C) for different times. The final time for cooking at every temperature was established by measuring the colour during the frying process. Deoxynivalenol reduction was greater in the artificially contaminated samples (>66% at 169 °C, 43% at 205 °C and 38% at 243 °C). For the level of 1200 μg/kg, the average percentage of deoxynivalenol reduction, based on medians, was 28% when the dough covers were fried at 169 °C, 21% at 205 °C and 20% at 243 °C.     

气相色谱法测定粮食中有机氯农药残留的操作改进探讨

通过实验对GB/T 5009.19-2008《食品中有机氯农药多组分残留量的测定》中的第二法做了改进,方法是浓缩提取液时,水浴温度应设定为50℃;水分过高的样品,应通过无水硫酸钠过滤其提取液。同时,将色谱条件中要求的填充柱改进为DB-35石英毛细管柱,应用程序升温对样品进行分离,改进后8种有机氯的回收率在80.17%~100.2%之间,相对标准偏差为1.13%~3.56%,方法的灵敏度、回收率、重复性和分离效果都得到很大改善。     

QuEChERS-超高效液相色谱-串联质谱法测定桑叶中64种农药残留

目的 建立QuEChERS结合超高效液相色谱-串联质谱法测定桑叶中64种农药残留的方法.方法 样品经乙腈提取,应用QuEChERS方法进行净化处理.使用Cortecs T3(2.1 mm×100 mm,2.7μm)色谱柱,用含0.1％(V/V)甲酸溶液(A)和甲醇(B)为流动相进行梯度洗脱,采用电喷雾电离(electr...