Challenges in the identification and characterization of free amino acids and proteinaceous compounds in atmospheric aerosols: A critical review

In the last decades, there has been an increasing interest in the presence of amino acids in atmospheric aerosols, either free or in combination (e.g., proteinaceous compounds). The fact that these compounds play an important role in the chemistry and physics of air particles and atmosphere, in atmosphere/biosphere nutrient cycling, and have a direct impact in human health has encouraged further studies. The diversity in origin, type, and ambient concentrations of these amino compounds considerably complicates, thus indicating their environmental impact. Studies for the determination of amino acids in the atmosphere are extremely diverse, encompassing an array of different analytical methodologies; however, it is not possible to conduct a comparative study of these methods. In this critical review, we evaluate and compare the procedures involved in the analytical methods and studies developed thus far for the identification and quantification of amino acids in different ambient particle sizes and in different atmospheric environments (i.e., background/pristine, rural, and urban environments). (C) 2015 Elsevier B.V. All rights reserved.