3D-Printed Stationary Phases with Ordered Morphology: State of the Art and Future Development in Liquid Chromatography

Abstract

Stationary phases with precisely ordered morphology have the potential to drastically improve the performance of chromatographic operations, both in the analytical and in the preparative/industrial fields. The recent wave of additive manufacturing, aka 3D printing, gives the unprecedented ability to fabricate such stationary phases and to experimentally prove the theoretical principles of ordered chromatographic beds. The manufacture of highly efficient chromatographic columns is becoming a reality as 3D printers become more affordable and accessible, and their resolution, speed, and material flexibility continue to grow. This brings fresh ideas to the design of chromatographic beds, moving away from stereotypical "packed" beds with spherical particles to bespoke monolithic structures to suit a range of specific applications. This review aims to cover the state of the art of ordered beds for liquid chromatography applications, drawing analogies between the well-established pillar-array columns in two dimensions to their three-dimensional counterparts. The potential use of 3D printing to create entirely new column formats and cartridge designs such as microchip columns will also be discussed. Finally, key opportunities and challenges which remain in the field of 3D-printed chromatography are summarised, with the hope that 3D printed chromatographic columns will soon become the standard.

Direct 3D printing of monolithic ion exchange adsorbers

“…The capability of 3D printing technologies to enable manufacturing of optimized three dimensional ordered structures has been recently discussed [8,10,12]. In particular, printing of complex monolithic structures with defined channel size, geometry and configuration tuned for specific separations is particularly attractive.…”

“…A range of serious barriers has so far limited the use of 3D printing methods in chromatography, e.g. the lack of materials compatible with both 3D printing processing and chromatographic operations, as well as the relatively poor resolution of current 3D printers to generate features in the micron scale [8].…”

Are we approaching a post‐monolithic era?

“… Active molding : As suggested by Tallarek and coworkers [31], active shaping of macroporous space would significantly increase transcolumn homogeneity of monoliths. Although this approach has been already demonstrated in the literature [38,39], it is necessary to introduce yet other protocols to improve radial homogeneity of polymeric separation materials. Additive manufacturing (3D printing) : Nowadays, 3D printing belongs to one of the most expanding directions in separation science [40–42], and there are already research groups devoting their potential to the development of 3D‐printed stationary phases [43–46]. A coverage of 3D‐printed scaffold by a polymeric material seems to be the simplest way to produce highly ordered stationary phases with selected surface chemistry.…”

3D Printing in analytical sample preparation

“…3D printing has also been used to facilitate LLE [31], and membrane separation [32] (Figure 2). Different reviews have been published covering the applications and potential of 3D printing in the field of analytical chemistry, including separation science [33,34], and online sample handling [35]. The present review is focused on the recently reported strategies to provide 3D printed devices with functionality for analytical sample preparation applications.…”