Browsing by Author "Parviainen, Riku"

The literature section of this thesis provides an overview of modern ion-mobility spectrometry techniques in context with recent applications in analytical chemistry. While ion-mobility spectrometry is an “old” separation technique, it has received in recent years increasing attention for its unique ability to achieve separation of isomeric molecular species. Ion-mobility spectrometry can be readily hyphenated with chromatographic and mass spectrometric techniques, introducing an additional separation dimension with the unique capability of differentiating isobaric analyte ions based on their collision cross sections. After a brief introduction into the theory of ion-mobility spectrometry, most recent applications in the field are presented with the focus being on the discrimination of small isomeric molecules. The research project section of the thesis reports the synthesis of isomerically pure standard materials of the commercially unavailable pepper alkaloids piperettine and piperettyline, and the qualitative and quantitative analysis of piperettine in selected pepper fruit samples. Strategies for the synthesis of piperettine reported in the literature are reviewed, and critically evaluated in terms of practicability and overall yields. A new, expedient, and operationally convenient synthetic approach to isomerically pure piperettine and piperettyline from inexpensive starting materials is described. In course of stability studies, both alkaloids were found to be stable in the crystalline states and as solutions in a range of organic solvents under exclusion of ambient light. However, diluted solutions of both compounds proved extremely photosensitive, with extensive double bond isomerization occurring within seconds upon sunlight exposure. An analytical method for the quantification of piperettine in pepper fruit samples was developed, involving liquid extraction, extract clean-up by solid-phase extraction, and HPLC-UV analysis. The use of a chiral stationary phase (Chiralpak IB) under optimized reversed phase condition allowed for the first time clean separation of piperettine from its naturally co-occurring isomers, and thus for its unambiguous quantification. Subsequently, this method was employed to quantify piperettine in black, green, white, and red long pepper samples. The observed piperettine content were 1.4 – 3.7 mg/g in the pepper fruit samples, representing 46 – 69% of the total sum of isomers.