Browsing by Author "Ruotsalainen, Sini"

The literature review of this thesis presents the most utilized sample preparation and analysis methods for determination of trace elements from refinery feedstocks and end products during the last decade. The advantages and disadvantages of used methods and trends are presented. The challenges associated especially on silicon determination are discussed and possible solutions provided by publications are highlighted. The experimental part of this thesis is conducted in Neste’s Research and Development unit in Porvoo. The experimental part includes method development, study of siloxane compounds behavior and method validation for various sample matrices. The method development was performed by introduction of peristaltic pump to inductively coupled plasma- mass spectrometer (ICP-MS) sample introduction for two different methods (ASTM D8110M, NM 534) to replace previously used free aspiration method. The study of behavior of volatile siloxane compounds in different sample matrices including liquified waste plastics (LWP), and determination of these compounds was done with ICP-MS. The studied siloxanes showed great challenges due to their high volatility with the chosen methods. The method (ASTM D8110M, NM534) validation for different sample matrices were also done with ICP-MS. The validated matrices included several renewable matrices such as liquified waste plastics, fatty acids and other liquified waste samples and heavy fossil distillates. Repeatabilities of silicon concentration of sample as such and as spiked in intra- and inter-day, and spiked recoveries played an important role for method validation.