Development of novel comprehensive multidimensional gas chromatography for improving separation and analysis of propylene oxide sample

Abstract

New experimental and data analysis approaches in multidimensional gas chromatography (MDGC) comprising 1) comprehensive two dimensional GC (GC×GC) and 2) comprehensive multiple heart-cut were developed with an example application illustrated for analysis of propylene oxide sample. GC×GC system employed column set of long first dimensional (1D) nonpolar (60 m) and short second dimensional (2D) polar (5 m) columns with a flow modulator and a Deans switch (DS) as a splitter; whilst, the comprehensive heart-cut system applied solely a DS located between long 1D nonpolar (60 m) and 2D polar (60 m) columns without use of cryogenic trapping devices. Under the same oven temperature program, the effects of different experimental conditions on the separation performances in GC×GC (injection time of the flow modulator and 2D column flow) and in comprehensive heart-cut ( heart-cut window and number of injections) were investigated. The analysis performance for each condition was evaluated according to peak capacity and number of separated compounds. The continuum between the two techniques was then established based on the analysis time vs analysis performance relationship. The separation performances were improved with longer analysis time so that the suitable condition can be selected within this compromise. The injection time of 0.60 s and 2D column flow of 14.0 mL/min were proposed as the best condition in GC×GC. For comprehensive heart-cut, the heart-cut window of 0.20 min with analysis time of 25 h was the selected condition. Under these conditions, volatile compounds in propylene oxide sample were identified according to matches between the experimental mass spectrometry (MS) spectra and first dimensional retention indices (1I) with that from NIST2014 database and the literatures. An hour analysis with GC×GC resulted in total peak capacity of 798, number of separated peaks of 61, number of identified compounds of 27 and average MS match score of 887±35. The corresponding numbers were improved to 9198, 107, 38 and 898±24, respectively, with the 25 h comprehensive heart-cut analysis.