HPLC 2012 was held 16–21 June in Anaheim, California, USA, for the first time in its long history. In this instalment, coverage
of some of the technology and application advances is reported. We review the overall liquid-phase chromatographic trends
observed at the symposium, the opening plenary session, awards presented, column technology highlights and sample preparation
and detector usage.
The 38th International Symposium on High Performance Liquid Phase Separations and Related Techniques, which alternates between
Europe and North America with occasional side meetings in Australasia, was held 16–21 June 2012, in Anaheim, California, USA,
for the first time (not far from Disneyland). More affectionately known as HPLC 2012, the symposium is the premier scientific
event for bringing together the myriad techniques related to separations in liquid and supercritical fluid media. Chaired
by Professor Frank Svec of the Lawrence Berkeley National Laboratory in Berkeley, California, USA, HPLC 2012 assembled 830
participants from all over the world. This number included vendor representatives (150) from 52 exhibitors for the three-day
instrument, software and consumables exhibition. Based on the lower number of attendees and exhibitors compared to HPLC 2011
in Budapest, the worldwide economic crisis may have played a role in the support for this important conference.
The five-day-plus event had a total of 117 oral presentations in plenary and parallel sessions and 443 posters in sessions
with 19 different themes. Attendees had their hands full deciding how to allocate their time with an ample social event schedule
including a symposium banquet at Disney California Adventure, nine vendor workshops, six "sunrise" tutorial educational sessions
and seven short courses (held during the previous weekend). The tutorials were particularly well attended and covered current
topics such as organic monoliths, selectivity optimization, hydrophilic interaction liquid chromatography (HILIC), higher
order protein structure, capillary LC and ion chromatography (IC) and supercritical fluid chromatography (SFC).
Trends in Liquid Phase Technology and Techniques
Obviously, high performance liquid chromatography (HPLC) was the predominant technology in the technical sessions at the symposium,
but sample preparation, the use of electrophoretic techniques (mostly in a capillary format) and an increase in method development
and method transfer papers were strongly evident. From a perusal of the poster and oral presentation abstracts and notes from
my colleagues, I broke down some of the major areas of coverage in this year's symposium. These tables are useful to spot
trends in the technology, applications of liquid phase separations and detection principles that were introduced in this series.
Table 1 provides a rough breakdown of the coverage of liquid-phase technology and techniques in the separation sciences. Compared
to HPLC 2011 (1), some slight shifts in technology emphasis were noted. Again this year, new developments in column technology
led the pack by far with more than a third of the oral and poster papers dealing with new phases and formats. Surprisingly,
nearly 40% of the columns' papers dealt with monoliths. Although not yet considered a commercial success, research interest
in this technology is still running high, especially in academia. The polymeric monolith segment is less covered by intellectual
property rights than the silica monolith segment. Second-generation silica gel–based monolith commercial products feature
better efficiency but slightly higher pressure drops because of the change in the macropore/mesopore domain ratio. Presentations
on polymer-based monoliths outnumbered silica-based monoliths by a 2.5:1 margin. This surprisingly high margin may have reflected
the bias of the symposium chair, who is a leader in this area of polymeric monolith technology. However, a continuation of
new developments in polymeric monoliths devoted to the separation of small molecules has shown improvements in column efficiency;
originally, the small molecule domain was for the silica-based monoliths and polymeric monoliths were thought to be useful
for macromolecules only.
Table 1: HPLC 2012 papers presented by technology or technique.
Three other "hot" areas in column technology this year were
Table 2: HPLC modes represented at HPLC 2012.
- More emphasis on the new breed of superficially porous packings (SPP, also referred to as shell particles, poroshell and fused-core
packings) that rival the sub-2-μm particles in terms of column efficiency, but with substantially lower pressure drops. The
poster and oral papers referring to SPP outnumbered those devoted to sub2μm totally porous particles by 60%.
- The widespread attention to HILIC for the separation of polar analytes that are weakly retained by reversed-phase chromatography.
This year, just for fun, I tabulated the various LC modes reported on at HPLC 2012 (Table 2). Clearly, as expected, reversed-phase
chromatography was the number one application mode but HILIC was a fairly strong number two.
- The incorporation of nanoparticles (embedded) into packing media seemed to generate a lot of research interest, especially
in polymeric media where the use of gold and carbon nanoparticles imparted higher surface areas (therefore increased capacity)
and enhanced selectivity. The nanoparticles themselves can be modified in situ with various functional groups and then used for separations of proteins and other molecules by selective interactions.
The interest in new research into sub2μm porous packings has waned a bit this year, probably because these columns are now
firmly established in the ultrahigh-pressure liquid chromatography (UHPLC) world with more than 30 vendors supplying these
products. On the other hand, there were considerable discussions about the practicality of whether the next generation of
smaller totally porous particles or superficially porous particles will approach the 1-μm dimensions.
Sample preparation technology was well represented in the poster papers and two oral sessions were devoted to some of the
current techniques. Most prominent were improved solid-phaseextraction (SPE) and solid-phase microextraction (SPME) technologies
with new phase chemistries: monoliths, immobilized enzyme in situ reactors, molecularly imprinted polymers (MIPs), dispersiveSPE phases for QuEChERS (quick, easy, cheap, effective, rugged
and safe) and mixed-mode phases providing new selectivities.
Electro-driven separation techniques (for example, capillary electrophoresis (CE), capillary zone electrophoresis (CZE), micellar
electrokinetic chromatography (MEKC) and isoelectric focusing (IEF) showed a slight drop-off compared to HPLC 2011 (1), but
continued to see a strong following in the application papers with great strides being made in interfacing to mass spectrometry
(MS). The developing interest in biopharmaceuticals has spurred a renewed interest in CE technologies for the separation of
biomolecules. A continued lack of interest in capillary electrochromatography (CEC) was noted with only nine presentations
at HPLC 2012.