Email: krisko@ku.edu
Education:
Area of Study:
The use of mass spectrometry as a detection scheme for high performance liquid chromatography (LC-MS) and capillary electrophoresis (CE-MS) has become a very powerful tool for challenges in the field of Bioanalytical Chemistry. Though both CE-MS and LC-MS have been previously used in a large number of bioanalytical applications, they are not without shortcomings. The detection limits of CE-MS are typically much worse than that of LC-MS and are further compromised by complex matrices present in biological samples. Development of separation methods for LC-MS can still be a time-consuming and labor-intensive process making its use in the pharmaceutical industry costly. The goals of this research are to enhance the detection limits of CE-MS for biological samples and to develop a way of making LC-MS method development much more efficient.
A CE/MS interface of the sheath flow design was constructed using a stainless steel Valco mixing tee. The analysis of a local anesthetic, bupivacaine, in rat urine was performed in order to identify the parent compound and metabolites. Following solid phase extraction, urine samples were analyzed by CE-MS. Bupivacaine and six of its unknown metabolites were identified in the urine extracts using exact mass and MS/MS experiments. In addition, two different instruments (a quadrupole-time-of-flight and a magnetic sector hybrid) were used to compare the utility and compatibility of both of the mass analyzers with CE. Experiments analyzing the oxidative DNA damage biomarker, 8-OHdG, in urine and microdialysis samples using CE/MS were performed in order to study oxidative stress in vivo. Exact mass and MS/MS experiments were used to identify an unknown isomer of 8-OHdG in a standard solution. The limits of detection for CE-MS have as of yet been insufficient to detect 8-OHdG at basal levels. A base-stacking strategy that is compatible with CE-MS is currently being developed in order to decrease the detection limits of the CE-MS system.
A strategy involving the use of DryLab computer simulation software in conjunction with a column selection system for HPLC was developed in collaboration with the Analytical Development Group at AstraZeneca. The strategy incorporated a large number of columns with different stationary phase chemistry in order to alter the selectivity of the separation, and the composition of the mobile phase was also manipulated. This was all performed in an automated fashion such that all experiments could be performed on an over-night or over-the-weekend basis. DryLab was used as a way to predict which column and separation conditions would give the best, acceptable separation. Furthermore, by manipulation of stationary and mobile phase chemistries, a wealth of information regarding the specificity of the separation was obtained in a short amount of time. What traditionally would take weeks to months to obtain required only a few days' time under the new strategy.
I was married on June 26, 1999 to my love, soul mate and best friend, Heather. I also enjoy football, going to baseball games, hunting, fishing, movies, good food (especially bacon), and having a good time with my friends. The picture of me was taken in the summer of 1998 during a fishing trip in Alaska.
