元素分析作业

化学与环境科学学院分析化学 20144015016 骆洪伟元素分析的原理及仪器介绍一、元素分析的基本原理1.有机元素定义有机元素通常是指在有机化合物中分布较广和较为常见的元素，如碳(C)、氢(H)、氧(O)、氮(N)、硫(S)等元素。

2.元素分析仪测定的原理待测样品在高温条件下，经氧气的氧化与复合催化剂的共同作用，使待测样品发生氧化燃烧与还原反应，被测样品组份转化为气态物质(CO2, H2O,N2与SO2)，并在载气的推动下，进入分离检测单元。

分离单元采用色谱法原理，利用气相色谱柱，将被测样品的混合组份CO2, H2O, N2与SO2载入到色谱柱中。

由于这些组份在色谱柱中流出的时间不同（即不同的保留时间），从而使混合组份按照N,C H,S的顺序被分离，被分离出的单组份气体，通过热导检测器分析测量，不同组份的气体在热导检测器中的导热系数不同，从而使仪器针对不同组份产生出不同的读取数值，并通过与标准样品比对分析达到定量分析的目的。

3.有机元素分析仪上常用检测方法主要有：示差热导法、反应气相色谱法、电量法和电导法。

二、Vario ELⅢ型元素分析仪介绍1.Function of the vario EL 仪器的功能The elementary analyzer vario EL is a fully automatic instrument for a speedy and quantitative determination of CHNOS. Depending on the purchased equipment , the instrument can-in different operation modes-determine the following elements simultaneously from one sample weigh-in: CHNS, CNS, CHN, CN, N, and S.元素分析仪vario EL是一个快速的，用于C、H、N、O、S定量测定的全自动仪器。

根据购买的设备，仪器能有不同的操作模式，从同一个样品称量中同时测定一些元素：CHNS,CNS,CHN,CN,N,和S。

The suitability of the vario EL analyzer for the element analysisdepends on the controllable combustibility of the samples or sample quantities.对元素分析来说，vario EL分析仪的适应性根据样品可控制的燃烧性和样品的量。

2.General Measuring Principle 通用测量原理The elementary analyzer vario EL works according to the principle of catalytic tube combustion in an oxygenated CO2 atmosphere and high temperatures. The combustion gases are freed from foreign gases (for instance volatile halogen). The desired measuring components are separated from each other with the help of specific adsorption columns and determined in succession with a thermal conductivity detector (TCD). Helium (He) serves as flushing and carrier gas.元素分析仪vario EL工作原理是根据在氧化的CO2气氛中和高温下接触反应的试管燃烧原理工作的。

燃烧气不含杂质气体（例如挥发性的卤素）。

需测量部分在特殊吸附柱和热导仪（TCD）连续测定的帮助下彼此分离。

氦（He）用于冲洗和载气。

3.Analysis 分析The automatic control of the analysis procedure is accomplished through the software and the sample specific nitrogen dosing is allocated through index numbers (O2-Index 1-5) to the appropriate sample matrix. The oxygen dosing can be regulated by the operator .分析程序的自动控制是通过软件完成的，样品特殊氮的是通过指数（O2指数1－5）分配到适合的样品矩阵。

加氧量能由操作者控制。

We will now explain the timely and functional course of an analysis. With the help of illustrations 4.1 and the figures/letters in brackets, it is possible to follow the location of the described process. Illustration 4.1 shows the simplified flow diagram of the CHNS mode, since all three possible adsorption columns (SO2, H2O, CO2) are built in. Depending on the mode of operation, only the adsorption columns of the elements to be determined are built into the gas line. To makeit clear, the adsorption columns should not be seen as bridged.我们将说明一个分析的适时的和功能的过程。

在图示4.1和括弧中的数字或字母的帮助下，能理解所描述过程的位置。

由于所有3个吸附管都是内置的（SO2, H2O, CO2），图示4.1显示了CHNS模式的简化的流程图。

根据操作模式，只有要被测定的元素吸附柱才能列入气体路线里面。

为了使它更清楚，吸附柱不应被看作为过渡。

图4.1 : vario EL （CHNS模式）的流程图LegendV2 valves for 6 ash crucible 灰坩埚7 reduction tube 还原管V3 desorption path SO2用于解吸附SO2通道的阀V4 O2-input valve O2输入阀8 drying tubes 干燥管V7 He-input valve He输入阀9 gas control insert 气体控制插入V8 valves for 10 flow controller, measuring side流量控制器，测量方面V9 desorption path H2O 11 detector (TCD) 热导仪用于解吸附H2O通道的阀A SO2-adsorption columnSO2吸附柱12 throttle, reference side 节流阀，参考方面B H2O-adsorption columnH2O吸附柱13 drying tube, reference gas 干燥管，参考气体C CO2-adsorption columnCO2吸附柱14 gauge, gas inlet pressure 量表，气体入口压力1 Carousel旋转式进样盘15 flowmeter for O2 and He 用于O2和He的流量表2 ball valve 球阀16 gas cleaning tube 气体清洁试管3 combustion tube 燃烧试管17 pressure sensor 压力传感器4 3-tube furnace可容3个试管的加热炉18 drying tube, oxygen 干燥管，氧5 O2-lance O2输入口19 needle valve for O2-dosing用于O2加入的针形阀4.Sample loading 样品装填The homogenized sample is packed in tin foil, weighed and placed into the carousel of the automatic sample feeder (1). The sample weight is entered into the PC either from an on-line balance via an interface or manually with the keyboard. The sample name and the matrix specific oxygen dosing (O2-Index 1-5) is allocated to the sample weight . Now the analysis can be started.均匀分布的微粒样品包裹在锡箔中，称重之后放入自动样品进样器的旋转式进样盘中（1）。

样品重量输入PC中，既可通过界面的在线天平也可用键盘手动输入。

样品名称和矩阵特殊的加氧量（O2-指数1-5）被分配到样品重量中。

现在分析能开始了。

At the start of an analysis, the Auto-Zero Adjust of the measuring signal is carried out through the detector (9). Thereafter the ball valve (2) opens through a 180° turn of the blind hole ball. The carousel (1) moves up one position and the sample drops into the blind hole of the ball valve (2). The ball valve (2) turns 90°into flushing position and seals the apparatus. The atmospheric nitrogen that had entered is now flushed out and after flushing is completed, the sample drops into the ash finger (6) of the combustion tube (3)through another 90° turn of the ball valve (2).在分析开始时，测量信号的自动调零通过检测器（9）执行。