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在定性分析中,常用灵敏度来评价某种鉴定反应的灵敏性。灵敏度在数值上表示为检出限量和最低浓度,检出限量和最低浓度不能根据理论推算,而是由实验确定的。但是,在现行的定性分析教科书中,确定溶液中鉴定反应最低浓度的方法不太合理。 例如:在分析化学实验教材中,确定NH_4SCN鉴定Fe~(3+)的反应的灵敏度时,是把Fe~(3+)浓度为10毫克/毫升的酸性试液不断地稀释,配制成一系列浓度的Fe~(3+)试液,然后分别用饱和的NH_4SCN溶液进行鉴定,根据颜色的变化来确定该鉴定反应的灵敏度。当取一滴
In qualitative analysis, sensitivity is often used to evaluate the sensitivity of some type of identification reaction. Sensitivity is numerically expressed as the detection limit and the lowest concentration, the detection limit and the lowest concentration can not be calculated according to theory, but experimentally determined. However, in current textbooks on qualitative analysis, it is not reasonable to determine the lowest concentration in solution for identification of reactions. For example, in the analytical chemistry experiment teaching materials, to determine the sensitivity of NH_4SCN to identify the reaction of Fe ~ (3+), the acidic test solution with Fe ~ (3 +) concentration of 10 mg / mL is continuously diluted to prepare a series of concentrations Of Fe 3+ solution, and then respectively with saturated NH_4SCN solution for identification, according to the color change to determine the sensitivity of the identification reaction. When taking a drop