微波消解-冷原子吸收法测定纸巾纸中的汞含量

采用微波消解技术处理样品,冷原子吸收法测定纸巾纸中的汞含量。对样品前处理中消解体系和消解条件进行讨论,确定了最佳使用条件。结果表明,该方法的回收率达到91.64%~102.66%,适用于纸巾纸中汞含量的检测。     

电感耦合等离子体质谱法测定肥料中21种元素的含量

建立了微波消解-电感耦合等离子体质谱法测定肥料中21种元素含量的方法。称取约0.5 g样品,加入10 mL硝酸和1 mL氢氟酸后于120℃预消解30 min,再加入2 mL过氧化氢加盖放置过夜,按程序升温微波消解,消解液赶酸后用5%硝酸溶液定容至50 mL,以钪、铑、铟和铼作为内标,用电感耦合等离子体质谱法测定。结果表明：各测定元素的线性关系良好,相关系数R≥0.9988,方法检出限为0.001～1mg/kg,定量限为0.01～5mg/kg,不同浓度水平下的平均加标回收率为80.9%～117.5%,相对标准偏差为0.16%～4.58%,该方法具有消解完全、操作简便、专属性强、灵敏度高、准确性好等特点,可满足有机肥、复合肥、化肥等多类型肥料中21种元素含量的快速准确测定需要。     

微波消解-电感耦合等离子体原子发射光谱仪（ICP—OES）测定玩具涂层中的铅元素

采用不同的微波消解温度和不同混合酸消解油漆粉末标准参考物（NISTSRM2582）,用ICP—OES测定铅元素的含量。依据精密度、回收率,比较了消解温度、混合酸对NISTSRM2582的消解效果。结果表明,由60mL浓硝酸和180mL浓盐酸混合后稀释到1000mL后组成的混合酸对玩具涂层具有很好的消解能力,微波加热15min能迅速有效消玩具涂层,铅元素的测定值与标称值非常符合。     

微波消解在茶叶和土壤稀土元素与重金属元素分析中的应用

采用微波消解法对茶叶和土壤样品进行处理,以ICP-MS测定了其中的稀土、重金属元素以及I,Te,Rb等鲜有报道的元素,完善了微波消解技术的应用体系,并与电热板消解法做了准确度、精密度与回收率比较。方法检出限(LOD)为0.4(Se)～0.001(Te)ng·g-1。实验证明,微波消解法能够完全满足土壤和茶叶中重金属与稀土元素消解的要求。     

微波消解样品-电感耦合等离子体质谱仪测定黑枸杞中硒、铜含量

目的：建立微波消解样品ICP—MS测定黑枸杞中的微量元素硒、铜的方法。方法：样品置于聚四氟乙烯罐中,加入硝酸及过氧化氢在微波消解仪中按设定程序加热消解。所得样品溶液定容至25ml后用电感耦合等离子体质谱仪（ICP—MS）测定其中硒、铜元素的含量。结果：采用此法具有灵敏度高、选择性好、样品用量少和多元素同测等优点,适用于食品、保健品中微量与痕量元素的分析。本次试验应用于分析圆白菜标准物质（GBW10014）,所得2种元素的测定结果与证书值一致。方法回收率在95％-102％之间。测定值的相对标准偏差小于5％。可用于测定黑枸杞中的硒、铜元素的含量。     

烟用接装纸中凉味剂的检测及释放行为分析

目的 考察烟用接装纸中凉味剂的释放行为,为明确烟用凉味接装纸的贮存期提供参考。方法 通过对样品前处理条件进行优化,采用气相色谱法测定接装纸中3种凉味剂的含量,基于该方法考察室温存放条件下各凉味剂的释放行为,并选取零级、一级、Higuchi和Korsmeyer–Peppas动力学模型对各凉味剂的释放行为进行拟合。结果 接装纸中凉味剂最佳提取工艺条件为摇床辅助提取,提取溶液为乙醇,溶液体积为25 mL,提取温度为30 ℃,振荡转速为160 r/min,提取时间为25 min。在130 d时接装纸中(–)–薄荷酮和L–薄荷醇释放率达78.04%以上,(–)–乳酸薄荷酯释放率仅为39.74%;3种凉味剂在接装纸中的释放行为均符合Korsmeyer–Peppas动力学模型。结论 文中方法适用于烟用凉味接装纸中(–)–薄荷酮、L–薄荷醇和(–)–乳酸薄荷酯的测定,较好地描述了3种凉味剂在接装纸中的释放过程,可为凉味型卷烟的品质监控和加工技术提供技术支撑。     

微波消解—原子吸收法连续测定天然胶乳中铜和锰

实验采用微波消解法消解样品,用原子吸收法在同一体系溶液中连续测定天然胶乳中铜和锰,传统方法采用干灰法或酸消化法消解样品,分光光度法测定,实验证明本法较传统方法节约时间、提高灵敏度和准确度,对人员及环境污染减少,该方法是一种比较好的测定天然胶乳中铜和锰的方法。通过试验测出铜和锰检出限分别为0.28μg/mL和0.15μg/mL,测定精密度的RSD值分别为1.17%和1.05%,铜加标回收率在94.43%～103.40%,锰加标回收率在91.30%～113.64%。     

微波消解-ICP-MS测定花草茶中金属元素含量

采用微波消解法对花草茶样品进行前处理,利用电感耦合等电子体质谱仪(ICP-MS)同时测定了样品中As、Cd、Cr、Pb、Sr、Mn、Cu、Zn等8种金属元素的含量。结果表明,采用微波消解-ICP-MS法的测得加标回收率为92.6~101.3%,实验结果满足检验要求,适用于花草茶中多种元素的同时快速确证检测。且该前处理方法相比干化法,检测时间更短,结果更准确。     

微波消解-ICP-MS法测定金银花和白芷中5种有害重金属元素

选取了不同产地及不同等级的10批次金银花和白芷进行测定,并建立了微波消解-ICP-MS法测定中药材中5种有害元素含量的分析方法,各元素的线性关系良好,灵敏度(cps/ng/mL)959～18116,相关系数0.999992～1.000000,定量限0.03～0.3ng/mL,线性范围0～100ng/mL.因其低检出限及高灵敏度,该方法能满足中药材样品质量控制中5种有害元素的测定要求.为中药材中该5种有害元素的准确测定提供参考.     

石墨炉原子吸收光谱法测定土壤中铅元素

山西省是我国重要的能源和重化工基地,由于煤矿开采、工矿企业废水的排放,造成周边土壤铅污染较严重,因此,准确检测矿区周边的铅元素很有必要.本文通过优化试验条件,使用石墨炉原子吸收法测定土壤中的铅含量,比较了微波消解和电热板两种消解方法对土壤标准物质的消解效果,测定出吕梁市某矿区周边土壤铅元素的含量.实验表明:石墨炉原子吸收法采用电热板消解,加入混酸(6mL氢氟酸、2mL高氯酸、2mL浓硝酸),该方法操作便捷,时间短,消解完全,结果可靠.在优化条件下,对购买的土壤标准物质的测定结果在标准值范围内,同时检测出3个土壤样品的含铅量分别为67.11,67.11,67.12,加标回收率分别为102.2%,94.93%,92.95%.     

Comparison of various digestion procedures in chemical analysis of spent hydrodesulfurization catalyst

Four digestion procedures have been tested to verify their applicability to the determination of major and trace elements (Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sr, Ti, V, Zn) in a spent catalyst by inductively coupled plasma optical emission spectrometry (ICP-OES). Two digestion procedures have been carried out in a closed microwave system using: (1) HCl+HNO(3)+H(2)O(2); (2) HNO(3)+HF, whereas the remaining two in an open system using: (1) aqua regia+NH(4)F, HNO(3), H(2)SO(4); (2) HF+HClO(4), H(3)BO(3), HCl. Among these four procedures the microwave digestion system (1) gave the best recovery results. The quality of the analytical results has been evaluated by the analysis of the CTA-FFA-1 Fine Fly Ash Certified Reference Material. A good agreement between the measured and reference values was found for almost all elements. The precision was assessed from the replicate analyses of microwave digestion (1) system and was found to be less than 5% of the relative standard deviation (R.S.D.).     

Effect of microwave irradiation on crystal growth of zeolitized coal fly ash with different solid/liquid ratios

In the present work, coal fly ash (CFA) was converted to zeolite (CFAZP) experimentally at atmospheric pressure via a conventional hydrothermal heating for 6 h at low temperature (90 ± 3 °C) followed by microwave irradiation for 30 min. The synthesized products were characterized using XRD, TGA/DTA, SEM, PSD, BET, and cation-exchange capacity (CEC) techniques. The effect of microwave on the crystal growth of nucleated CFAZP at different solid/liquid ratios (suspended CFA mass to NaOH solution volume, g/mL) was studied. A three-variable, three level central composite statistical experimental design was applied to investigate the effect of the independent variables on the response function defined as the ratio of the characteristic peak intensity at 2θ: 28° of a sample to that of the same peak of a sample run for 24 h with conventional heating. The relative peak intensity of CFAZP as high as 97% was achieved under optimum experimental conditions with 1 M of NaOH concentration, 6 h of conventional heating followed by 30 min microwave irradiation with a solid/liquid ratio of 0.40 g/mL. Under constant microwave energy, higher solid/liquid ratios led to higher relative peak intensity of the product.     

Fabrication of hydrothermal ageing resistant of 3 mol % yttria-stabilised tetragonal zirconia polycrystalline via microwave sintering

The influence of microwave sintering on the densification, mechanical performances, microstructure evolution and hydrothermal ageing behaviour of pure 3 mol % yttria-stabilised tetragonal zirconia polycrystalline (3Y-TZP) ceramics was compared with conventional sintered samples. Green bodies were sintered via conventional pressure-less and microwave sintering method between 1200 °C to 1400 °C with dwelling time and firing rate at 120 min, 10 °C/min and 1 min, 20 °C/min. Result showed that reduced processing temperature and holding time is possible with microwave sintering technique for fabricating good resistant zirconia sample with bulk density, Young's modulus, and Vicker's hardness that are comparable to samples sintered with conventional method. However, the microwave sintered samples suffered from hydrothermal ageing where their average grain size is above critical size. The enhancement of hydrothermal ageing resistance of the sintered samples is associated with the decreasing grain size of the sintered samples instead of sintering method.     

Pore pressure and explosive spalling in concrete

Results of an experimental study, which measured thermally-induced pore pressure and corresponding concrete temperatures in high-strength concrete (HSC) and normal strength concrete (NSC), to quantify the effects of factors influencing pore pressure buildup and potential for explosive spalling in HSC and NSC are presented. The specimens are 100 × 200 × 200 mm concrete blocks, heated to a maximum temperature of 600°C (1,112°F) at 5°C/min (41°F/min) and 25°C/min (77°F/min). The complex heat-induced moisture transport process, which varied with specific levels of concrete temperature and significantly influenced the developments of pore pressure and concrete temperature, is explained. Pore pressure developments are shown to be directly related to the moisture transport process and have a significant influence on occurrence of explosive spalling. Effects of water-to-cementitious materials ratios (w/cm), curing conditions, heating rates, and polypropylene (PP) fibers on pore pressure buildup and explosive spalling are quantified and described.     

Microwave-assisted protein solubilization for mass spectrometry-based shotgun proteome analysis

Protein solubilization is a key step in mass spectrometry-based shotgun proteome analysis. We describe a microwave-assisted protein solubilization (MAPS) method to dissolve proteins in reagents, such as NH(4)HCO(3) and urea, with high efficiency and with an added benefit that the solubilized proteins are denatured to become more susceptible to trypsin digestion, compared to other conventional protein solubilization techniques. In this method, a sample vial containing proteins suspended in a solubilization reagent is placed inside a domestic microwave oven and subjected to microwave irradiation for 30 s, followed by cooling the sample on ice to room temperature (~40 s) and then intermittent homogenization by vortex for 2 min. This cycle of microwave irradiation, cooling, and homogenization is repeated six times. In this way, sample overheating can be avoided, and a maximum amount of protein can be dissolved. It was shown that in the case of trypsin digestion of bovine serum albumen (BSA) more peptides and higher sequence coverage could be obtained from the protein dissolved by the MAPS method than the conventional heating, sonication, or vortex method. Compared to the most commonly used vortex-assisted protein solubilization method, MAPS reduces the solubilization time significantly, increases the amount of protein dissolvable in a reagent, and increases the number of proteins and peptides identified from a proteome sample. For example, in the proteome analysis of an Escherichia coli K-12 integral membrane protein extract, the MAPS method in combination with sequential protein solubilization and shotgun two-dimensional liquid chromatography tandem mass spectrometry analysis identified a total of 1291 distinct proteins and 10363 peptides, compared to 1057 proteins and 6261 peptides identified using the vortex method. Because MAPS can be done using an inexpensive microwave oven, this method can be readily adopted.     

Modelling of Migration from Printing Inks on Paper Packaging

The migration model of contaminants from inks on paper packaging to food is developed based on the penetration of ink in paper and Fick's diffusion. The printed paper is divided as ink layer and paper layer. The mass transfer coefficient h_m and partition coefficient K_F,P in the interface between paper and food are considered in the model. The model equation is solved, and the migration expression is obtained by using the method of separation of variables. The fitting method is used between the model and the migration experimental data to obtain the diffusion coefficients and mass transfer coefficients for dibutyl phthalate (DBP) and acetyl tributyl citrate (ATBC). It is found that there exist linear relationships between ln(D_P) and 1/T, and also between ln(h_m) and 1/T for DBP and ATBC. The migrations of DBP in the paper sample 2402 at different temperatures and of ATBC in the paper sample 2401 at 50°C are predicted by using the model, and a good agreement is obtained between the model predictions and the migration experimental data. Copyright © 2014 John Wiley & Sons, Ltd.     

Sintern von TiO2 im Mikrowellenfeld

Sintering of Titania under Microwave-Conditions A microwave sintering device was implemented at the Technical Institute of the Friedrich-Schiller-Universität Jena equipped with an applicator combining conventional high frequency with microwave heating. Additionally a dilatometer was integrated to measure shrinkage or expansion respectively. The device allows a reliable comparison of the materials behaviour treated under conventional and microwave conditions. Titania was used to prove that coupling and sinter behaviour can be assessed reproducible via measuring temperature and shrinkage. Titania samples with a green density of about 60% of theoretical density accept efficiently microwave energy above 940°C, heating rates of more than 300 K/min were measured. At 1360°C final densities of 98% TD were achieved within 40 minutes. Compared to conventional sintered titania (1400°C, 3 hours) microwave heating resulted in a significant smaller grain size.     

Effect of microwave irradiation on carbon fiber/epoxy resin composite fabricated by vacuum assisted resin transfer molding

The effects of microwave irradiation for resin-curing of carbon fiber/epoxy resin composite (CFRTS), which was fabricated by vacuum-assisted resin transfer molding (VARTM) method, were investigated at 2.45 GHz frequency. The mechanical properties of CFRTS cured by microwave irradiation for 20 min at 120 °C were similar as compared to the conventional oven for 300 min at 120 °C. Moreover, the CFRTS irradiated by microwave had better adherence property between fiber and resin as compared to conventional oven at same resin-curing time. From the relation between resin-curing and mechanical property, it was found that the curing rate of microwave-irradiated CFRTS was 15 times faster as compared to conventional heating. Furthermore, the activation energies for resin-curing reaction on conventional- and microwave-cured CFRTS were estimated to be 2.7 and 1.3 × 10⁴ J/mol, respectively. The resin-curing reaction in CFRTS prepared by VARTM method was significantly promoted by microwave irradiation at short time.     

微波消解地质样品方法探讨

该文利用UltraCLAVE微波消解仪对地质样品进行消解,提出消解用酸的种类和用量,以及消解过程中的一些注意事项。方法优化微波消解的实验条件,速度快,污染少,操作简便安全,消解能力强且效果好,能满足地质样品简单、快速、批量分析的要求。