Development and evaluation of Consumable-free planar microfluidic modulators for comprehensive two-dimensional gas chromatography

Abstract

The analysis of the volatile and semi-volatile fraction of complex samples remains a challenge to separation scientists due to the overwhelming number of sample components and the wide range of physical and chemical properties exhibited by the analytes. Among all instrumental techniques available today, comprehensive two-dimensional gas chromatography is considered the most remarkable and valuable technique for the separation, detection, and identification of organic compounds, applicable to any sample (e.g., biological or food samples and petrochemical derivatives). However, the main factor that still hampers its wide spread use in routine analysis is the aggravated cost with consumables (e.g., liquid nitrogen). Hence, the present research proposal will aim at the development and evaluation of consumable-free planar microfluidic modulators as an alternative to commercially available cryogenic modulators. To accomplish this goal, we will explore the fundamentals of chromatography and combine them to the state-of-art in heat transfer technology used in high efficiency electronic devices. The prototypes will consist of two-stage thermal modulators by combining alternated steps of sorptive trapping and thermal desorption. Analyte trapping will occur by sorption to a thick non-selective stationary phase (e.g., polydimethylsiloxane) operated at low temperatures to favor the distribution constant of the analytes in the two-phase system. The thermal desorption of the analytes, on the other hand, will be accomplished by exploring microfabricated resistive heating systems imparted with reduced thermal mass. In addition, among the numerous experimental parameters that will be evaluated and optimized, we highlight the geometry of the modulation channels, as it will play an important role in heat transfer and, especially, to the average linear velocity of the chromatographic bands inside the microfluidic modulator. Lastly, the results of this work will be crucial to understand thermal and sorptive modulation in microfabricated systems for GC×GC. We hope that the scientific knowledge generated by this research will culminate in the development of an economical and marketable interface for GC×GC. (AU)