# Atomic Spectroscopy-Based Analysis of Heavy Metals in Seaweed Species
## 2 Atomic Spectroscopy-Based Heavy Metal Analysis Methods for Seaweed
### Atomic Mass Spectrometry  
Mass spectrometry, where separation and quantification of metals are achieved on the basis of different trajectories of moving ions with different mass/charge (\(m/z\)) ratios in electrical and/or magnetic fields, is an important tool for heavy metal analysis in the food industry. The removal of spectral interference provided by the newly emerged triple quadrupole mass spectrometers has enabled researchers to develop methods to measure some of the elements/metals that used to be challenging [89; 90]. Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)  
Although ICP-OES is an excellent and powerful tool for the analysis of metals in food samples, ICP-MS can offer even lower detection limits and a higher dynamic range (6-7 orders of magnitude) in trace metal analysis in one run. The ICP-MS technique, which involves the use of an atomic mass spectrometer, benefits from the high temperature of plasma as a highly efficient ionization source to separate and measure atoms or elements. The instrument is equipped with a quadrupole mass spectrometer that provides high sensitivity, simple spectra, and fast scanning capability. ICP-MS combines the rapid, simultaneous, multi-element capability of ICP-OES and the sensitivity of GFAAS. Since in ICP-MS, only the generated ions are measured, the plasma is optimized and focused for more efficient ionization which results in higher sensitivity. Analysis at levels below the 10 ppb to ppt range can be performed using ICP-MS. However, when comparing ICP-OES and ICP-MS, if all the target elements are consistently at concentrations above 10 ppb, then ICP-OES is the better option, since ICP-MS is affected by different types of interferences. While selection of the most appropriate combination of reactive gas and scan settings can help with removing the interferences, this demands a more sophisticated level of operational skills from most users of ICP-MS instrumentation [71]. The most common disadvantages of ICP-MS include relatively low tolerance to total dissolved solids and susceptibility to matrix effects. Despite the simplicity of mass spectra in comparison with emission spectra, spectral interferences, such as isobaric overlap, overlap from polyatomics, and doubly charged species, need to be addressed. Furthermore, the possible nonspectral interferences are transport effects, ionization interferences, and ion sampling effects [91]. The effects of nonspectral interferences can be alleviated by the addition of suitable internal standards that are similar in terms of mass, ionization potential, and concentration to the target analytes. Recently, sector field high resolution instruments provide better sensitivity and partial solutions for spectral interferences. Moreover, newer ICP/MS techniques using collision cell and dynamic reaction cells help in reducing polyatomic interferences. These advancements in ICP-MS instrumentation have made the quantification of P and S at low levels or isotope measurements of essential elements, such as Fe and Se, possible. Examples of heavy metal analysis in seaweeds at different geographical locations using ICP-MS are given in the following sections, and the detected concentrations are presented in Table 4.