Haloacetic Acids in the Aquatic Environment

Haloacetic acids (HAAs) are a class of disinfection by-products (DBPs), widely occurring in drinking water, wastewater and swimming pool water with concentrations at sub-μg/L to mid-μg/L levels. HAAs arose public attention due to their cytotoxicity, genotoxicity and carcinogenicity. Monitoring HAA concentration levels in aqueous environments is required. This review presents an overview of all techniques or methods for sample pretreatment, analysis and removal of HAAs in aqueous environments since 2000. For the pretreatment methods, the commonly used methods are compared and discussed in terms of advantages and drawbacks. Microextraction techniques are preferred as they are efficient, rapid and environment-friendly. Emerging pretreatment methods, such as techniques based on novel materials or liquids, have also been introduced. For the analytical methods, LC and GC coupled with various detectors are frequently used allowing detection at the required low μg/L levels in aquatic environments. The advances in mass spectrometers (MS) and a comparison between their pros and cons are summarized herein. Recent high resolution MS gave give mass accuracy of 0.0001 Da with a resolving power up to 140,000 full width at half maximum height improving feature identifications in nontargeted analyses. For HAA removal methods, advanced oxidation techniques, adsorption and biodegradation were updated, improved and upscaled. Combining two or more removal techniques, the efficiency can reach 99%. Lastly, this review points out critical gaps and proposes future trends.