4. Analytical methods for arsenic quantification

The "total arsenic" determined in a sample most often do not represent a valuable information, because of the different properties and different toxicity of its species [19, 20]. The main problem is the easy conversion of the arsenic species to another caused by the pH changes, the presence of reducing agents, oxidizers, and certain bacterial strains able to produce a lot of organic As-species [21, 22]. That is why the As speciation is the only important way to characterize the origin of the As-related problems such as its toxicity and biogeochemical cycling and to find the best procedure for drinking water treatment. Unfortunately, As speciation remains challenging, because of the interference between the arsenic species possessing different toxicity [23], which is typical for the organic As-species [24, 25].

The best analytical methods for As speciation are considered those, including chromatographic separations [26, 27] such as IC [28] and HPLC [29], coupled with a sensitive detection system, such as ICP–MS, AFS–HG, and AAS–HG [30]. Specific sorbents and exchange resins have been developed and applied recently for this purpose [31–35]. Apart from the chromatographic and non-chromatographic methods for the arsenic species separation, simple and cost-effective electrochemical methods were developed recently based on the distinct As-species electrochemical properties [36, 37].
