闪蒸对昌黎产区‘马瑟兰’葡萄酒单体酚类物质的影响

以欧亚种酿酒葡萄‘马瑟兰’为试材,研究闪蒸处理对葡萄酒发酵及陈酿过程中单体酚类物质和CIELab色泽参数的影响。结果表明,与传统浸渍发酵（对照组）相比,闪蒸有利于提高发酵过程中多数单体花色苷的质量浓度,但不利于保持陈酿过程中各单体花色苷质量浓度。闪蒸增加了葡萄酒发酵及陈酿过程中槲皮素-3-O-葡萄糖苷、儿茶素、反式白藜芦醇及白藜芦醇葡萄糖苷等非花色苷单体酚类物质的质量浓度,但降低了槲皮素、杨梅酮、酚酸类单体酚、顺式白藜芦醇及白皮杉醇等酚类物质的质量浓度。闪蒸处理可降低葡萄酒亮度L*、黄蓝度b*值和色调角hab,显著增加红绿度a*、色度Cab*值,使葡萄酒颜色更红、更深、更耐陈酿,两组葡萄酒间颜色差异明显。结论：闪蒸有利于增加‘马瑟兰’葡萄酒单体酚总质量浓度及葡萄酒颜色的稳定性。     

RT-FQPCR法快速检测葡萄酒中醋酸菌群

建立一种快速、灵敏的检测葡萄酒中醋酸菌群的检测技术。通过改进葡萄酒中脱氧核糖核酸（DNA）提取方法,设计醋酸菌通用引物,优化实时荧光定量聚合酶链式反应（RT-FQPCR）条件,确定葡萄酒中醋酸菌的快速检测方法,同时利用7种醋酸菌对该方法的通用性、特异性以及灵敏度进行了验证。结果表明,7种醋酸菌均具有明显扩增曲线;非目的菌在该种条件下未见扩增,综合检测灵敏度为124 CFU/mL。以10种市售葡萄酒为基质,在其中添加醋酸菌均可检测出目标添加菌株。该方法通用性强,可用于葡萄酒中醋酸菌群的检测。     

稳定同位素技术在禽类及其制品溯源领域的研究进展

本文基于国内外禽类及其制品溯源的研究成果,针对市场上出现的禽类及其制品的产地和饲养方式造假(如普通鸡蛋冒充地理标志鸡蛋、自由散养鸡蛋、有机鸡蛋等)、禽类饲料成分掺假(如非法添加动物副产品、色素等)等问题,梳理了稳定同位素技术在禽类及其制品可追溯性的应用进展,在此基础上提出禽类及其制品溯源的现存问题和发展方向,以期为稳定...     

自动QuEChERS结合气相色谱-串联质谱法测定花生油中172种农药残留

目的：基于自动QuEChERS方法建立了花生油中172种农药残留的气相色谱-串联质谱(gas chromatography-tandem mass spectrometry,GC-MS/MS)快速检测技术。方法：花生油样品加水后,加入15 mL乙腈提取,放入自动QuEChERS前处理设备,以N-丙基乙二胺(primary secondary amine,PSA)和十八烷基硅烷键合硅胶(C18)为填料进行净化。净化后,取2 mL上清液,在氮气气流下吹至近干,用1 mL乙酸乙酯复溶后,过0.22 μm有机微孔滤膜,应用气相色谱－串联质谱(GC-MS/MS)检测,HP-5MS UI气相色谱柱分离,程序升温,在多重反应监测(MRM)模式进行测定,采用基质匹配外标法进行定量。结果：方法所检测的172种农药的线性决定系数(R_²)均大于0.995,检出限范围为1～5 μg/kg,定量限范围为2～10 μg/kg;在10 μg/kg、50 μg/kg和100 μg/kg 3个添加水平下,平均回收率在70.1%～112.8%、72.6%～114.3%、71.8%～114.9%范围内,相对标准偏差(RSDs)均小于15.0%(n=6)。结论：该方法操作简单,灵敏高效,能够满足花生油中多农药残留检测的需求,也可以为复杂基质的自动化前处理提供参考。     

Study on the determination of rare earth elements in coal ash by ICP-MS

Abstract

In this paper, an analytical method for the determination of rare earth elements in coal ash by mixed acid decomposition-inductively coupled plasma mass spectrometry was established. Using this method, the content of 15 rare earth elements in coal ash can be detected accurately, with the detection limit being 0.007–0.033?μg·g^?1, and the precision (RSD, n?=?6) less than 5.0%. This method was used to test the coal ash of different commercial coals. The results show that the light rare earth elements in coal ash account for 75.66%–82.61% of the total rare earth elements, among which, the total amount of rare earth elements in Yitai coal after being ashed is significantly lower than that of other coals.     

自动QuEChERS结合液相色谱-串联质谱法测定香叶中的212种农药残留

目的 建立自动QuEChERS结合液相色谱-三重四极杆串联质谱法测定香叶中212种农药残留.方法 香叶样品用乙腈提取,使用300 mg十八烷基硅烷键合硅胶(C18)+75 mg Nano-Carb、4.0 g无水硫酸镁和1.0 g氯化钠进行净化,经自动样品制备系统进行制备后,应用液相色谱-三重四极杆串联质谱法进行检测,...     

云南3种特色蜂蜜的挥发性成分测定与比较

为探究云南三种特色蜂蜜挥发性物质组成和差异,采用顶空固相微萃取-气相色谱-质谱法对云南三种特色蜂蜜(苕子蜜、澳洲坚果蜜、橡胶蜜)挥发性成分进行测定,结合主成分分析(PCA)和偏最小二乘法判别分析(PLS-DA)模型进行分析。结果表明:三种蜂蜜共检测出105种挥发性物质,苕子蜜检出61种,澳洲坚果蜜检出55种,橡胶蜜检出62种。苕子蜜主要挥发性成分为醛类、酸类和醇类,含量较高的物质为正壬醛和乙酸。澳洲坚果蜜主要挥发性成分为醇类、萜烯类和醛类,含量较高的物质为顺式-氧化芳樟醇和呋喃甲酸芳樟醇氧化物,特征挥发性物质为反式芳樟醇3,7-氧化物。橡胶蜜主要挥发性成分为醛类、醇类和酸类,含量较高的物质为壬醛和反式呋喃芳樟醇氧化物。PCA和PLS-DA分析结果表明,澳洲坚果蜜、苕子蜜和橡胶蜜挥发性成分之间存在显著差异,三种蜂蜜被100%准确分类。本研究表明,苕子蜜、橡胶蜜和澳洲坚果蜜有各自独特的挥发性成分,据此构建的PCA和PLS-DA模型可以实现云南这三种特色蜂蜜的有效分类鉴别。     

Degradation of Wax in Soil and Its Effect on the Nitrogen Release Behavior of Polyurethane Coated Urea

Abstract

The polyurethane coated urea (PCU) was prepared by coating granular urea with the coating material, which was composed of castor oil, chain extender, polymeric MDI and wax. The wax as the sealant of the porous polyurethane coating was used to regulate the nitrogen (N) release rate of PCU. The test of N release behavior showed that the controlled-release effect of PCU in soil was inferior to that in water. Compare the analysis results of the PCUs in water, in alkaline water and in soil respectively, it showed that the structure of PU coatings was almost unchanged after immersion in water, and alkaline water, but after being buried in soil, the wax was degraded by microorganisms in the soil. The degradation of the wax changed the roughness and hydrophilicity of the coating. Calculation from IR demonstrated a loss trend of wax similar to the N release trends within 30?days, and the wax in the PU coating with 8?wt% wax degradated about 38?wt% after the coating was buried in soil for 40?days. The work shows that the stability of coating materials in water cannot prove his stability in soil. In order to make the PCU supply N slowly for a longer time in soil, wax or sealants with higher stability in soil should be selected and applied to the polyurethane coating.     

Ultrafine cobalt–molybdenum–boron nanocatalyst for enhanced hydrogen generation property from the hydrolysis of ammonia borane

The hydrolysis of ammonia borane (NH₃BH₃) is recognized as an efficient way of hydrogen generation if it can be effectively catalyzed. In this work, a series of cobalt–molybdenum–boron (Co–Mo–B) nanoparticles (NPs) on copper (Cu) foil are introduced as catalysts for NH₃BH₃ hydrolysis by electroless deposition method. The influence of the depositing pH value on the catalytic property is investigated by adjusting the pH value ranged from 10.5 to 12.0. By optimizing the value to 11, the ultrafine Co–Mo–B NPs with the grain size around 4.3 nm show the best catalytic property for NH₃BH₃ hydrolysis. The hydrogen generation rate reaches 5818.0 mL·min⁻¹·g⁻¹ when the hydrolysis temperature is 298 K. The thermodynamic tests show that the lower activation energy (E_a) is estimated to be 59.3 kJ·mol⁻¹. It can be found that the catalytic property in this work overtakes that of partial non-precious metal NPs, and is even better than some precious metal NPs previously reported. The hydrolysis reaction of NH₃BH₃ catalyzed by ultrafine Co–Mo–B NPs is a non-spontaneous process. In addition, the cycling ability of the ultrafine Co–Mo–B NPs is also studied and the results demonstrate that the catalyst is a recyclable one toward the hydrolysis of NH₃BH₃ under mild reaction conditions.     

Fluorescent detection of clenbuterol using fluorophore functionalized gold nanoparticles based on fluorescence resonance energy transfer

A new fluorescence method for detecting clenbuterol based on gold nanoparticles (AuNPs) and rhodamine B (RB) has been developed. It has been observed that the quenching of fluorescence of RB occurs in the present of AuNPs through the fluorescence resonance energy transfer (FRET). In the presence of clenbuterol, the FRET-based fluorescence of RB and AuNPs would be gradually recovered for the reason that clenbuterol could congregate the AuNPs and inhibit the FRET process. An assay for the determination of clenbuterol has been proposed based on the modulation in FRET efficiency between RB and AuNPs. Under the optimum conditions, the fluorescence recovery efficiency of the assay is proportional to the concentration of clenbuterol. The detection limit in swine feed was calculated to be 0.008 mg/g and the recoveries were in the range of 97%–102%. In short, the proposed method provides advantages such as rapidity, simplicity, low cost and high sensitivity, making it promising for the rapid screening of clenbuterol residues.