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1 Chapter 12 The Analysis of Real Sample (31-34)
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2 Quantitative analysis steps 1.Selecting a method 方法选择 2.Sampling 取样 3.Preparing a laboratory 实验室样品制备 4.defining replicate samples 确定重复测定 次数 5.preparing solutions of the samples 溶样 6.eliminating interferences 排除干扰 7.completing the analysis 分析 8.computing the results and estimating their reliability 结果计算及数据评价
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3 Real samples are far more complex than those that you encounter in the instructional laboratory. 实际样品测定复杂性 31A Choice of method for the analysis of real samples The choice of a method for the analysis of a complex substance requires good judgment and a sound knowledge of the advantages and limitations of the various analytical available. 为复杂物质选择分析方法需要很 多相关知识。
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4 31A-1 Definition of the problem 确定需要解决的问题 Concentration of species 形态浓度 Accuracy 准确性 Other components 共存组成 Properties of sample 样品性质 The number of samples 样品数量
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5 31A-2 Investigation of the literature 文献调研 The technology for computer-based scientific information retrieval provides an efficient means for surveying the analytical literature. 计算机查询文献。 The various analytical journals may be consulted. Monographs on methods for completing the analysis are valuable in deciding among several possible techniques. 各种分析杂志及专著可提供技术指导。
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6 31A-3 Choosing or devising a method 选择或设计方法 decide upon the route to be followed in the laboratory. Simple or complex 简单还是复杂 The number of samples 样品数量 Error and interferences 误差与干扰 It is to be hoped that one or more tentative methods worth testing will have been located. 最好试验几种方案
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7 31A-4 Testing the procedure 方法检验 The analysis of standard sample 标准样分析 Analysis by other method 其它分析方法比较 Standard addition to the sample 标准加入法 31B The accuracy obtained in the analysis of complex materials Table 31-1---31-5
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8 Preparing Samples for Analysis 样品制备 32A Sample 取样 32A -1The effects of sampling uncertainties s 2 =s s 2 +s m 2 s s sampling process error s m method error
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9 Decomposing and dissolving the sample 样品分解 33A sources of errors in decomposition and dissolution 样品分解中误差 Incomplete dissolution of the analyte 溶解 不完全 Losses of the analyte by volatilization 蒸发损失 Introduction of analyte as a solvent contaminant 溶剂影响 Introduction of contaminants from reaction of solvent with vessel walls. 器皿污染
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10 33B Decomposing samples by inorganic acid in open vessels HCl,HNO 3,H 2 SO 4,HClO 4,HF Oxidizing mixture 33C Microwave decompositions
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