Metal-Organic Framework Stationary Phases for One- and Two-Dimensional Micro-Gas Chromatographic Separations of Light Alkanes and Polar Toxic Industrial Chemicals

Douglas H Read; Colin H Sillerud; Joshua J Whiting; Komandoor E Achyuthan

doi:10.1093/chromsci/bmaa005

Metal-Organic Framework Stationary Phases for One- and Two-Dimensional Micro-Gas Chromatographic Separations of Light Alkanes and Polar Toxic Industrial Chemicals

J Chromatogr Sci. 2020 Apr 25;58(5):389-400. doi: 10.1093/chromsci/bmaa005.

Authors

Douglas H Read¹, Colin H Sillerud², Joshua J Whiting³, Komandoor E Achyuthan³

Affiliations

¹ FENG and Tube Lifecycle Engineering Department, Sandia National Laboratories, Albuquerque, NM 87185, USA.
² CFV Solar Test Laboratory, Albuquerque, NM 87106, USA.
³ Nano and Microsensors Department, Sandia National Laboratories, Albuquerque, NM 87185, USA.

PMID: 32291439
DOI: 10.1093/chromsci/bmaa005

Abstract

Despite promising advances with metal-organic frameworks (MOFs) as stationary phases for chromatography, the application of MOFs for one- and two-dimensional micro-gas chromatography (μGC and μGC × μGC) applications has yet to be shown. We demonstrate for the first time, μGC columns coated with two different MOFs, HKUST-1 and ZIF-8, for the rapid separation of high volatility light alkane hydrocarbons (natural gas) and determined the partition coefficients for toxic industrial chemicals, using μGC and μGC × μGC systems. Complete separation of natural gas components, methane through pentane, was completed within 1 min, with sufficient resolution to discriminate n-butane from i-butane. Layer-by-layer controlled deposition cycles of the MOFs were accomplished to establish the optimal film thickness, which was validated using GC (sorption thermodynamics), quartz-crystal microbalance gravimetric analysis and scanning electron microscopy. Complete surface coverage was not observed until after ~17 deposition cycles. Propane retention factors with HKUST-1-coated μGC and a state-of-the-art polar, porous-layer open-tubular (PLOT) stationary phase were approximately the same at ~7.5. However, with polar methanol, retention factors with these two stationary phases were 748 and 59, respectively, yielding methanol-to-propane selectivity factors of ~100 and ~8, respectively, a 13-fold increase in polarity with HKUST-1. These studies advance the applications of MOFs as μGC stationary phase.