共沉淀—火焰原子吸收法测定食品和废弃物中痕量铅、镉、铬、铟

发布时间：2019-03-03 20:36

【摘要】：社会的发展与进步必然会导致人们对于环境、食品中安全意识的不断增强,因此也会不断催生出越来越多的检测方法和检测仪器。在实际分析检测过程中会碰到各种各样的现实问题与尴尬境地亟待我们解决：比如火焰原子吸收法的操作方便、仪器价格便宜、灵敏度高,但是检测限不够低,达不到要求；再比如电感耦合等离子体发射光谱法的灵敏度高、检测限可以达到ppb级别,但是仪器价格高昂,普通实验室或检测机构根本无力承担。那么既可以使用成本低、操作快捷的火焰原子吸收法又可以使检测方法的检出限降低成为我们的研究目标。共沉淀方法是应用范围较广的一种分离富集预处理方法,它简单、快速而且富集倍数高,与火焰原子吸收法联用可以检测痕量的重金属。本论文创新性地将以Bi(Ⅲ)、Al(Ⅲ)、Ba(Ⅱ)作为载体离子,以常见、便宜易得的1-(2-吡啶偶氮)-2-萘酚(PAN)作为共沉淀剂,共沉淀分离富集食物(如市售皮蛋、生花生及果酱)中的铅、镉、铬和废弃物(如废旧无汞碱性电池)中的铟,并采用火焰原子吸收法对上述四种痕量重金属的含量进行测定。通过讨论共沉淀剂1g/L PAN的加入量、一定浓度载体离子Bi3+、Al3+、Ba2+的加入体积、溶液pH值、共沉淀时间、样品体积等因素选择最优共沉淀体系,通过分析共存离子的干扰、灵敏度、精密度、检出限等论证了方法的优越性。本论文还对相应的共沉淀机理类型进行了研究,不仅有利于对分析分离的理解而且可能对其它方面的研究有一定的指导意义。本文研究了如下四个体系来分离富集特定的痕量重金属：一、Bi(Ⅲ)-PAN共沉淀体系检测皮蛋样品中的Pb。该方法的灵敏度为0.0143(mg/L)-1,精密度为1.31%,对铅的检出限为16.3μg/L。按正常程序进行共沉淀(以下均称先加)和先形成Bi(Ⅲ)-PAN再加入含铅样品(以下均称后加),以上二者共沉淀形式均为表面吸附共沉淀。二、Bi(Ⅲ)-PAN共沉淀体系检测生花生中的Cd。该方法灵敏度为0.1528(mg/L)-1,检出限为3.40μg/L,精密度为0.16%。先加时Cd与Bi(Ⅲ)-PAN部分形成混晶与固溶体部分形成表面吸附,而后加时主要形成表面吸附。三、Al(Ⅲ)-PAN共沉淀体系检测果酱中的Cr(总)。灵敏度为0.0461(mg/L)-1,检出限为8.98 μg/L。先加和后加含铬(总)试样时,Al(Ⅲ)-PAN与Cr的的共沉淀形式均为表面吸附。四、Ba(Ⅱ)-PAN共沉淀体系检测废旧电池中的In3+。该方法检测痕量重金属铟的灵敏度为0.0147(mg/L)-1,检出限为20.4μg/L,方法精密度为0.79%。无论是先加样品还是后加样品Ba(Ⅱ)-PAN与痕量In3+的共沉淀形式均为表面吸附共沉淀类型。
[Abstract]:The development and progress of society will inevitably lead to the continuous enhancement of people's awareness of environment and safety in food. Therefore, more and more testing methods and instruments will be produced. In the process of practical analysis and detection, various practical problems and awkward situations need to be solved. For example, the operation of flame atomic absorption spectrometry is convenient, the instrument is cheap, the sensitivity is high, but the detection limit is not low enough to meet the requirements. For example, Inductively coupled Plasma Emission Spectrometry (ICP-AES) has high sensitivity, and the detection limit can reach the ppb level. However, the instrument is expensive and can not be borne by ordinary laboratories or testing institutions at all. Therefore, flame atomic absorption spectrometry (FAS), which can be used with low cost and fast operation, can reduce the detection limit of the detection method to become our research goal. Coprecipitation is a widely used pretreatment method for separation and preconcentration. It is simple, rapid and has high enrichment ratio. It can be used in combination with flame atomic absorption spectrometry for the determination of trace heavy metals. In this paper, Bi (鈪，

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