Analysis of environmental polycyclic aromatic compounds and related biomarkers using GC-APLI-MS

In this work, various applications for APLI-MS are presented. Thereby, the main focuswas set onto the hyphenation of GC and APLI-MS. The most important goal in thiscontext was to implement an analytical method for PAH analysis in environmentalsamples. The resulting method enables to quantify 57 PAH in various solid samples attrace level. With LOD between 5 and 50 fg absolute on column even smallest amounts ofPAH can be detected. Method validation and analysis of certified reference materialsdemonstrated GC-APLI-MS to be a reliable and universal tool for the analysis of two- tosix-ring PAH in environmental matrices. Complementary application of LC-APLI-MSenables even consistent PAH analysis covering high molecular PAH.In general, GC-APLI-MS turned out to be a valuable tool in environmental analysis as itdelivers unique sensitivity and valuable selectivity. Therefore it represents a goodsolution in scientific questions and analytical problems where standard techniques fail.However, it is not a low budget technique as necessarily only expensive ultra-puresolvents have to be used, the maintenance of an excimer laser causes high fix costs andthe sample preparation includes several cleaning steps. In addition, due to the measuredtrace-level concentrations of an analyte occurring ubiquitously in the environment, therisk of contamination is high and has to be handled very seriously. For this reason, GCAPLI-MS can be regarded as a good solution in special issues, were high sensitivity orselectivity is needed, but disproportionate for standard PAH analysis. In this context, inthe following, exemplary reasonable applications of this new method, covering differentscientific questions, were demonstrated.First, soot samples were analyzed to distinguish characteristics of soot depending ondifferent burnt biomasses. For this purpose, different kinds of wood were burned andsoot was collected. To apply comparable conditions to all samples and to avoid furthergas phase reaction in the soot not related to the wood type, soots were collected duringthe same short period of 5 min. Therefore, only small amounts of sample were availableand the sensitivity of GC-APLI-MS became mandatory. Furthermore, PM collected frombiomass combustion was analyzed, which was applied to study gene expression profilingof human epithelial cells under influence of these particles. Due to the limited amount ofmaterial of PM that was further on mainly needed for cell culture and gene expressionexperiments GC-APLI-MS was required to quantify PAH associated to PM. In addition, GC-APLI-MS was applied to high throughput effect-directed analysis ofsediments. In this project, extracts of sediment samples were separated by LC andfractions were collected in 96 well plates for toxicity testing. For chemicalcharacterization, GC-APLI-MS was applied as there were only small volumes of eachfraction available and the concentrations of organic contaminants were comparativelylow. The analysis of bioactive fractions revealed, that the AhR related toxicity cannot besolely explained by the content of priority pollutants. In contrast, it seems to be linkedwith the occurrence of alkylated PAH.In addition to PAH analysis, GC-APLI-MS was used to analyze BaP related biomarker ofPAH exposure. For this purpose, methods were developed to determine the BaPmetabolites3-OH-BaP and BaP-tetraol in human urine. As these analytes occur in urineonly at very low concentrations and typically, in biomarker studies often only smallamounts of samples are available for each parameter, the high sensitivity of GC-APLIMSwas a great advantage. Even though method development was challenging due toinstability of analytes and the complexity of the urine matrix, both biomarker could bedetected successfully.Besides biomarker of PAH exposure, organic biomarker for the occurrence of eucaryotesin the ancient environment were analyzed in form of triaromatic steroids. Thesedegradation products of steroids are used as diagnostic markers for the existence ofeucaryotes as well as for the diversity of organisms and the ancient depositionsalconditions. To detect even the smallest traces of triaromatic steroids, highly sensitivemethods are necessary. As they exhibit an aromatic structure, they are prone toionization using APLI.In summary, GC-APLI-MS was demonstrated to be a reliable method to analyzearomatic compounds in general and PAH in special in environmental samples. This setupprovides unique sensitivity and selectivity and displays high variability in potential applications.