A panel of experts discuss the latest trends in sample preparation.
This article was written as part of a special series to commemorate 30 years since the launch of LC Magazine, which evolved into LC GC Europe and LC GC North America.
This is certainly an accomplishment that we in the separations community have enjoyed and benefited from, and we wish many
more happy years of success. This article is intended to be a follow-up of a sample preparation special report published in
1995 by Ron Majors, entitled "Trends in Sample Preparation and Automation — What the Experts Are Saying" (1). Now, we have
asked a new panel of experts similar questions on sample preparation. This is a compilation of what these experts think about
the current practice of sample preparation, and where they predict it will be 10 years from now. Just for fun, comparisons
to the predictions of the expert panel in 1995 have been made where possible.
Sample preparation remains the single most challenging aspect of chemical analysis. Chromatographic instrumentation, including
column technology, instrument reliability, durability, capabilities and most certainly detector technology, continues to advance
and move the business of chromatography forward at a steady pace and frequently with an incremental leap. Sample preparation
still relies on scientists' basic chemical knowledge of the analytes being measured; the techniques and methods they have
to measure them; and the experience to couple this knowledge effectively. Fortunately, advances in chromatography and chromatographic
detection have reduced some of the need for complex and tedious sample preparation. But, as our experts reveal, challenges
still remain.
How valuable are automated sample preparation techniques, such as supercritical fluid extraction (SFE), microwave extraction,
automated solvent extraction (ASE) and solid-phase extraction (SPE)?
In 1995, the overall general opinion of the earlier panel was that sample preparation was a manual technology, considered
"low-tech" and assigned to the least trained staff. Now, that is changing. "Sample preparation stations are becoming more
and more powerful, and aside from extraction and enrichment they offer features of standard addition, derivatization and so
forth," says Pat Sandra from the University of Ghent. "The application of automated sample preparation units with injection
(that is, on-line systems) is presently rather limited but will become more and more important in the future." Other experts concur that for automated sample preparation to realize its goals of being commercially advantageous, efficient
and "green," samples need to be run in parallel batches, similar to how sample preparation is done using manual labour. If
sequential sample handling is the automated mode of operation, it should be very rapid and subsequently integrated with parallel
analysis of final extracts to expedite the whole process. All the panelists agree that simple solvent based extractions can
be faster and easier for a few samples and sometimes using SPE or SFE just to concentrate, purify or desalt samples in preparation
for further mass spectrometry (MS) analysis is the simplest procedure to follow.
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