Study on steric transition in asymmetrical flow field-flow fractionation and application to characterization of high-energy material

• Published in: Journal of Chromatography A Vol. 1304; pp. 211 - 219
• Main Authors: Dou, Haiyang, Lee, Yong-Ju, Jung, Euo Chang, Lee, Byung-Chul, Lee, Seungho
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 23.08.2013; Elsevier
• Subjects: Algorithms; Analytical chemistry; Applied sciences; Asymmetrical flow field-flow fractionation (AF4); Asymmetry; Beads; Channels; Chemical industry and chemicals; Chemistry; Chromatographic methods and physical methods associated with chromatography; chromatography; Exact sciences and technology; Explosive Agents - isolation & purification; Fractionation; Fractionation, Field Flow - methods; Industrial chemicals; latex; Microspheres; Normal mode; Other chromatographic methods; Particle Size; Polystyrene resins; polystyrenes; Polystyrenes - chemistry; Powders, propellants, explosives; RDX; RDX particles; Reproducibility of Results; Size determination; Steric transition; Steric/hyperlayer mode; Transmission electron microscopy; Triazines - isolation & purification; Steric/hyperlayer mode; Normal mode; Asymmetrical flow field-flow fractionation (AF4); RDX particles; Steric transition; Nitramines; Field flow fractionation; Particle separation; Surface structure; Separation method; Transmission electron microscopy; Hexogen; Morphology; Explosives
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2013.06.051

•The steric transition phenomenon in asymmetrical flow field flow fractionation (AF4) was investigated.•Steric transition point was affected by the crossflow rate, but neither by the channel thickness nor the feed flow rate.•The sized-based selectivity (Sd) would be improved by increasing channel thickness.•Higher lift forces FHL caused by higher feed flow rate, in some cases, may allow more accurate size analysis.•Recrystallized RDX particles prepared by a supercritical anti-solvent (SAS) precipitation method were separated and characterized by AF4. In field-flow fractionation (FFF), there is the ‘steric transition’ phenomenon where the sample elution mode changes from the normal to steric/hyperlayer mode. Accurate analysis by FFF requires understanding of the steric transition phenomenon, particularly when the sample has a broad size distribution, for which the effect by combination of different modes may become complicated to interpret. In this study, the steric transition phenomenon in asymmetrical flow FFF (AF4) was studied using polystyrene (PS) latex beads. The retention ratio (R) gradually decreases as the particle size increases (normal mode) and reaches a minimum (Ri) at diameter around 0.5μm, after which R increases with increasing diameter (steric/hyperlayer mode). It was found that the size-based selectivity (Sd) tends to increase as the channel thickness (w) increases. The retention behavior of cyclo-1,3,5-trimethylene-2,4,6-trinitramine (commonly called ‘research department explosive’ (RDX)) particles in AF4 was investigated by varying experimental parameters including w and flow rates. AF4 showed a good reproducibility in size determination of RDX particles with the relative standard deviation of 4.1%. The reliability of separation obtained by AF4 was evaluated by transmission electron microscopy (TEM).