Development of GC-HRMS procedures for determination of naturally occuring polar compounds in various environmental applications 

Detta är en avhandling från Stockholm : Department of Applied Environmental Science (ITM), Stockholm University

Sammanfattning: The overall objectives of this dissertation were to gain further understanding of the two following environmentally significant issues: (i) Determination of natural steroid hormones in blood plasma from perch (Perca fluviatilis) during a reproductive cycle and to evaluate the possibility of using the steroid composition as a biomarker for early signs of endocrine disruptive effects. (ii) Determination of dissolved free amino acids in size resolved airborne particles collected over the Arctic pack ice area (>80°N) in summer and to study their overall relationship with the ocean surface microlayer as a potential source. This was made possible by the development of two separate gas chromatographic–high resolution mass spectrometry methods. To enable separation with gas chromatography both steroids and amino acids had to be chemically modified to increase their volatility. The small sample volumes available and low concentrations of analytes required a multi-step clean-up procedure to enable determination. The results showed that the circulating levels of steroids in perch varied over the year and that the levels of some androgens were lower in female perch exposed to leachate from a refuse dump compare to unexposed perch, which may explain the decline in fertility observed for the former group. This also indicated that the steroid composition in the blood plasma may function as a sensitive biomarker. The levels of dissolved free amino acids were enriched in the submicrometer aerosol, peaking in sizes around 100nm aerodynamic diameter. These findings do support a previous assumption that the most likely source for these particles is the surface microlayer of the open water between the ice floes. The most likely exchange mechanism of biogenic matter between ocean and atmosphere is the bursting of bubbles at the surface of the leads. This mechanism would provide a very important and poorly understood link between cloud radiative properties and marine biochemistry in the summer high Arctic (>80°N) through the production of cloud condensation nuclei.

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