Analyzing Contamination of Heavy Metals - AAS and Fluorescence Spectroscopy

Determination of heavy metals in soil, water, food, pharmaceuticals and environment samples has received great attention due to their serious threat to the ecology and human health. Indeed, technological advancements led to the rapid and real time detection and quantification of heavy metals in various samples. In this chapter, we focused on instrumentation, sample preparation, methodology and analysis of different heavy metals by atomic absorption spectrometry (AAS) and Atomic fluorescence spectroscopy (AFS). The main advantages of AAS and AFS are their high sensitivity, anti-interference ability, lower limit of detection (LOD) and wide range of analysis. AAS consist of following main parts; light source, atomizer, monochromator, detector, and a display device. Analytical samples were first prepared by acid digestion in organic acids such as HClO4, HCl, HNO3, and aqua regia before injection in AAS. A standard calibration curve is used to determine the unknown concentration of a sample. AAS is further classified as flame atomic absorption spectrometry (FAAS), graphite furnace atomic absorption spectrometry (GF-AAS), and hydride generation atomic absorption spectrometry (HG-AAS) which are exclusively used for the detection of various metal ions. Similarly, AFS consists of a light source, sample holder and detector. The sensitivity of AFS is mainly due fluorescent probes, quantum dots (QD) as probes are very specific with high degree of sensitivity and multiplexing property. The QDs made of graphene, carbon and semiconductors are mainly used for the detection of heavy metals via a calibration curve method. Till date, numerous studies were conducted to determine the heavy metal ion concentration in soil, water, and environment samples by using AAS and AFS. However, there are still some problems in these techniques which need to be resolved by additional research efforts.