A simple method for monitoring of removal of arsenic species from drinking water applying on-site separation with solid phase extraction and detection by atomic absorption and X-ray fluorescence based techniques

Total arsenic (As) as well as As(III) and As(V) species were monitored in drinking water with elevated As content sampled at waterworks of four settlements located in Hungary by means of on-site, solid phase extraction with a strong anion exchanger followed by As determination by either high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS) or total-reflection X-ray fluorescence spectrometry (TXRF). Total As concentrations in well water samples varied between 40 μg/L and 120 μg/L. Additionally, the occurrence of As(III) in each studied well water exceeded 80% of the total As content. On the other hand, As(V) was found to be the predominant species (≈ 90%) in water samples with reduced As concentrations (i.e., after treatments at waterworks) below the health limit value of 10 μg/L prescribed by the 98/83/EC Council Directive. Moreover, As could not be detected in the As(III)-associated fractions of several samples. Generally, a reasonable agreement was found between the results obtained with HR-CS-GFAAS and TXRF. Nevertheless, As concentrations in the As(III)-associated fractions collected after the flocculation and coagulation steps were below the detection limit of the TXRF method at a higher extent. Preliminary application of this simple As speciation approach enables a proper choice of reagents and their dosage for similar water treatment technologies and hence, a reduction in the water treatment costs. The current SPE method coupled off-line to cost-effective atomic spectrometric detection for monitoring inorganic As species in waters represents an alternative approach to conventional As speciation methods, thus it could be extensively exploited for routine analysis in water quality control laboratories.