微波技术在分析化学中的应用

对微波技术在现代分析化学中的应用作了综述，主要涉及在试样干燥，试样消解，微波萃取，微波雾化等方面的应用，微波技术的优点反映在高效、快速，操作控制较简单，及无化学污染等。对该技术的未来应用的展望也作了简述（引用文献46篇）。     

微波炉消解法测定环境水样中化学耗氧量

采用微波炉密封加热消解,硫酸-重铬酸钾消解体系测定环境水样中COD,试样经微波加热后过量的重铬酸钾以试亚铁灵为指标,用硫酸亚铁铵进行滴定。与回流消解法相比,具有省时、省试剂等优点。而且还能提高方法的精密度。     

微波脱磺-气相色谱法测定直链烷基苯磺酸钠的平均相对分子质量

在气相色谱法测定直链烷基苯磺酸钠的平均相对分子质量中,采用微波加热脱磺预处理方法,试样置于盛有磷酸的密闭聚四氟乙烯(PTFE)消解罐中,在微波消解系统中先在150℃加热10 min,随后在180℃加热5 min,微波消解系统的输出功率为300 W.试验证明,与GB/T5178-1985中所述的热裂解脱磺法相比较,微波脱磺法在操作简单,处理耗时少及保证结果的准确可靠等方面显示其突出优点.在气相色谱测定中采用了HP-5石英毛细管色谱柱(25 m×0.32 mm,0.25 μm)及氢火焰离子检测器.     

微波加热快速测定腐植酸总量

利用微波加热技术，在密闭容器内通过压力浸提、消解试样、能大大加快分析速度，本实验测定了不同煤样中的腐植酸总量，讨论了功率、时间、酸度等因素对分析结果的影响，并与标准方法相对照，用ｔ－检验法及Ｆ－检验法检验，没有明显差异，结果令人满意，该法具有省时、省力、经济、不污染环境，宜于批量分析，便于普及推广等优点。     

微波消解法测定高锰酸盐指数

高锰酸盐指数是以高锰酸钾为氧化剂 ,测得化学需氧量 ,一般仅限于地表水、饮用水、生活污水的测定[1] 。常规的高锰酸盐指数测定法需在常压下用沸水浴加热 30ｍｉｎ(从水浴重新沸腾起计时 ) [2 ] ,所需时间较长。用微波消解法测定ＣＯＤｃｒ方法已有报道[3,4 ] ,但对高锰酸盐指数测定方法未见报道。本文采用微波消解的方法对高锰酸盐指数测定方法进行改进 ,在常压下 ,用理论ＣＯＤ 5 0 0ｍｇ·Ｌ-1的葡萄糖溶液作为分析试样。通过对火力调节、微波时间、酸度等条件试验 ,建立了微波消解测定高锰酸盐指数方法。结果表明 ,微波消解具有高效、…     

微波消解法测定饲料骨粉中磷

利用微波加热技术,在密封增压罐内消解饲料试样,优选出酸消解体系、消解时间、酸用量等最佳条件,比色法测磷。该法快速、经济、准确。     

微波消解试样-原子荧光光谱法测定土壤中硒碲

应用HG-AFS法及微波加热试样消解法测定了土壤中硒和碲的含量,对试样消解参数、仪器工作条件及氢化物发生反应条件等作了试验并讨论.该方法测定硒及碲的检出限均为0.01μg·g-1,荧光强度与硒及碲的质量浓度在5～100μg·L-1及0.5～10μg·L-1范围内呈线性关系.应用此方法分析了3个土壤试样,测定值的相对标准偏差(n=6)均小于5%.用标准加入法作了回收试验,硒的回收率在92.0%～102.6%之间,碲的回收率在90.1%～98.8%之间.     

微波消解-分光光度法测定石油焦中的钒

研究了用微波消解分光光度法测定石油焦中的钒。在石油焦样品处理中采用了常规溶样及微波消解两种方法。重点研究了微波消解石油焦样品的方法，详细考察了微波消解时样品的最佳用量、消解压力、功率、时间，建立了最佳微波消解程序。结果表明两种方法测定结果基本吻合。样品测定的RSD小于4、02％，加标回收率均在98．6％～102．7％之间，但微波消解法的溶样速度是常规法的10倍。钒的线性范围为0～8．0g／L。结果表明，微波消解分光光度法测定石油焦中的钒是一种快速、准确且无环境污染的方法。     

微波消解-火焰原子吸收光谱法测定污泥中铅

研究了微波消解-火焰原子吸收光谱法测定污泥中铅。应用正交试验设计法确定了微波消解试样的最佳条件。该法与传统敞口消解法测定结果吻合。样品测定结果的相对标准偏差（n=6）为1.5％～4．7％，加标回收率为93．0%-106．2％。该方法省时省酸，减少环境污染，改善了工作环境。     

微波在分析化学及有机合成中的应用

综述了近10年来微波技术在分析化学和有机合成中的应用，着重介绍了微波消解在分析化学和微波辐射在有机合成反应中的应用进展。     

微波辐射对TiO2制备及其光催化氧化乙醛性能的影响

采用微波辐射与常规加热法由TiO₂溶胶制备出TiO₂催化剂，采用高频低功率微波-光催化装置考察了微波对两种催化剂上CH₃CHO光催化氧化转化率和产物分布的影响。结果表明，微波干燥制备的TiO₂晶体比普通加热制备的TiO₂晶体对乙醛有更高的光催化活性和更强的氧化能力，且它们对乙醛光催化氧化的途径不同，前者的初始中间体为甲醛和甲酸，后者的初始中间体却为乙酸。还发现，微波辐射对两种样品上乙醛的光催化转化率有不同的影响，对微波辐射法所制样品的影响比对常规加热法所制样品的影响显著。微波辐射通过场效应可加速光催化初始中间体的转化，但它不改变光催化反应的途径，反应途径取决于光催化剂的特性。     

A microwave digestion-based determination of low molecular weight organic acids in Bayer process liquor

A new technique for the determination of low molecular weight organic acids in Bayer process liquors is reported. The acids are partitioned from acidified liquor into butanol, followed by butylation using microwave heating. This method is both rapid (sample preparation time < 15 min) and capable of detecting acids larger than previously reported in the low molecular weight fraction (up to RMM 176). A standard solution containing 15 acids was used to calibrate the technique and 13 of these acids were detected and quantified in a Bayer liquor sample.     

微波技术在催化剂制备中的应用

微波作为一种独特的加热手段在化学领域已得到广泛应用。本文综述了微波技术在催化剂的合成、活性组分的负载等方面的研究应用，重点探讨了在分子筛催化剂的合成中微波技术所表现出的优越性，对微波合成催化剂的作用机理及影响因素作了评述，并展望了微波技术在催化领域的发展前景。     

Synthesis of LaCoO<Subscript>3</Subscript> from lanthanum trisoxalatocobaltate(III) (LTC) precursor employing microwave heating technique

Lanthanum cobaltite LaCoO₃, an important catalyst and an electronic material used as cathode in solid oxide fuel cells was prepared from lanthanum trisoxalatocobaltate(III) hydrate [LaCo(C₂O₄)₃]·9H₂O (LTC) employing microwave heating technique. It was observed that LTC heated in microwave heating system gives a pure product of LaCoO₃ at 400°C within one hour. Thermogravimetry, differential thermal analysis and X-ray diffraction techniques were used to optimize conditions for microwave processing of the precursor.Authors are thankful to Mr. N. A. Kulkarni and Mr. V. M. Chopade from TIFR, Mumbai for recording the XRD patterns of the sample.     

Analytical-scale microwave-assisted extraction

Microwave-assisted extraction (MAE) is a process of using microwave energy to heat solvents in contact with a sample in order to partition analytes from the sample matrix into the solvent. The ability to rapidly heat the sample solvent mixture is inherent to MAE and the main advantage of this technique. By using closed vessels the extraction can be performed at elevated temperatures accelerating the mass transfer of target compounds from the sample matrix. A typical extraction procedure takes 15-30 min and uses small solvent volumes in the range of 10-30 ml. These volumes are about 10 times smaller than volumes used by conventional extraction techniques. In addition, sample throughput is increased as several samples can be extracted simultaneously. In most cases recoveries of analytes and reproducibility are improved compared to conventional techniques, as shown in several applications. This review gives a brief theoretical background of microwave heating and the basic principles of using microwave energy for extraction. It also attempts to summarize all studies performed on closed-vessel MAE until now. The influences of parameters such as solvent choice, solvent volume, temperature, time and matrix characteristics (including water content) are discussed.     

微波在样品消解中的应用

介绍微波消解样品的基本原理、特点、应用及注意事项。用微波消解样品，效率高、速度快、易于控制、对环境无污染，应用于矿石、金属、食品、化工产品、医药及环境样品等样品化学分析的预处理，是传统加热消解样品的理想替代方法。     

Silicon carbide passive heating elements in microwave-assisted organic synthesis

Microwave-assisted organic synthesis in nonpolar solvents is investigated utilizing cylinders of sintered silicon carbide (SiC)--a chemically inert and strongly microwave absorbing material--as passive heating elements (PHEs). These heating inserts absorb microwave energy and subsequently transfer the generated thermal energy via conduction phenomena to the reaction mixture. The use of passive heating elements allows otherwise microwave transparent or poorly absorbing solvents such as hexane, carbon tetrachloride, tetrahydrofuran, dioxane, or toluene to be effectively heated to temperatures far above their boiling points (200-250 degrees C) under sealed vessel microwave conditions. This opens up the possibility to perform microwave synthesis in unpolar solvent environments as demonstrated successfully for several organic transformations, such as Claisen rearrangements, Diels-Alder reactions, Michael additions, N-alkylations, and Dimroth rearrangements. This noninvasive technique is a particularly valuable tool in cases where other options to increase the microwave absorbance of the reaction medium, such as the addition of ionic liquids as heating aids, are not feasible due to an incompatibility of the ionic liquid with a particular substrate. The SiC heating elements are thermally and chemically resistant to 1500 degrees C and compatible with any solvent or reagent.