Can Multiple Mass Spectrometry Platforms Make Indistinguishable Organic Micro-Pollutants Distinguishable in the Natural Environment?

Human, industrial, and agricultural practices release numerous organic macro- and micro-pollutants that impair the environment. Unlike macro-pollutants, micro-pollutants are poorly characterized and present a new set of challenges that need to be overcome to understand their presence, fate, and transformation in the environment. Derived from a diverse and growing list of sources, micro-pollutants can enter the environment directly or through ineffective wastewater processing streams. At present, the overall abundance of individual micro-pollutants in the environment is low and generally does not exceed microgram per liter levels. However, micro-pollutants can be resistant to numerous modes of biotic and abiotic degradation in the natural environment leading to a potential increase in their abundance. Moreover, in many cases, micro-pollutants and/or their transformation products are bio-active leading to their accumulation and having negative impacts on health.

Using a combination of multiple mass spectrometry systems of different resolving powers and analytical strengths (i.e., Isotope Ratio Mass Spectrometry [IRMS], High Resolution Mass Spectrometry [HRMS], and Tandem Mass Spectrometry [MSMS]) enables a comprehensive assessment of micro-pollutants. This combined approach allows us to generate unique multi-stable isotopic (¹³C/¹²C and ¹⁵N/¹⁴N), molecular fragment, and chemicals patterns that may serve as collective fingerprints for the identification/recognition, transformation, and overall assessment of degradation state or mode of micro-pollutants. We will discuss details and strengths of this approach using a subset of organic micro-pollutants that include nitrobenzene [NB], nitroguanidine [NQ], 2,4-dinitroanisole [DNAN], and 3-nitro-1,2,4-trizol-5-one [NTO].