Christopher Wabnitz

Project:

Optimizing Sample Preparation for CSIA

Accurate isotope measurements in compound specific isotope analysis (CSIA) for complex samples (e.g., environmental) often require extensive purification procedures to separate the target analyte (e.g., pesticide) from possible interfering matrices (e.g., natural organic matter, NOM). For an optimal and efficient purification, simultaneous online monitoring and quantification of both the pesticide and the NOM is highly valuable. While there are numerous methods for the online quantification of pesticides (e.g., UV/Vis or MS), online NOM monitoring poses a bigger challenge since (i) most used instruments can merely monitor certain fractions of NOM (e.g., chromophoric or ionizable), (ii) not compatible with organic solvents (e.g., TOC analyzer), or (iii) too expensive (e.g., FT-ICRMS).

In my PhD thesis, I am developing a measurement technique that is able to online monitor and quantify NOM during purification procedures. For this purpose, we couple a quartz crystal microbalance (QCM) with an LC system through a custom-made microfluidic spray-dryer. Combining the UV data on the analyte retention time with the QCM data on the NOM allows us to quantify NOM co-elution. Using the data gained with the QCM allows us to optimize purification procedures for CSIA