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Abstract

In order to quantify low concentrations of dopamine in complex biological matrices, a capillary electrophoresis-mass spectrometry pH stacking method was developed and optimized. The pH stacking method operates by concentrating the analyte on-capillary through manipulation of electrophoretic mobility in regions of different pH. This method allowed for a detection limit of 0.1 ng/mL, approximately 2 orders of magnitude lower than using a more traditional capillary zone electrophoresis (non-stacking) method. The stacking method was determined to be linear from 0.5-1000 ng/mL dopamine with accuracy values within 10% and precision values within 5% across the range. A CE compatible method for the extraction of dopamine from intracellular and extracellular cell culture components was also developed. This method was then applied to the analysis of dopamine in STHdh cells, a model for Huntington’s disease, showing a lower concentration of dopamine in disease cells compared to normal phenotype, consistent with current literature data on Huntington’s disease. In addition, steps were taken toward the development of a CE-MS method for the measurement of uridine diphosphate sugars in cerebrospinal fluid with advantages including short analysis time (<20 mins) and low sample consumption.