Advancing Chromatographic Analysis Using Selective and Robust Sample Preparation

Sample preparation plays a very important role in chemical analysis, and has become an integral step prior to chromatographic separations. Depending on the sample matrix and the overall goal of analysis, the employed sample preparation approach can range from "dilute and shoot" to more laborious solid-phase extraction methods. With ongoing advances accelerating chromatographic separations, sample preparation methods must exhibit most, if not all, of the following characteristics: They must be capable of achieving rapid and high enrichment or preconcentration of target analytes; they must be tolerant of matrix effects; they must exhibit robustness under conditions commonly encountered during sampling and analysis steps; and they must demonstrate compatibility with downstream chromatographic and mass spectrometry methods. The field of sample preparation is undergoing revolutionary change, largely governed by the need for miniaturization while maintaining high selectivity and high analyte enrichment. This change has necessitated the development of new sorbent materials, as well as the design of creative geometries that possess high surface areas and facilitate rapid diffusion of analytes from a variety of samples. This supplement was assembled to showcase advances in various sample preparation approaches from leaders in the field. They have applied their methods towards environmental, food, and pharmaceutically relevant samples to demonstrate the marriage of these techniques with chromatographic separations for solving important challenges in chemical analysis.

Jared L. Anderson

Emanuela Gionfriddo and co-workers at The University of Toledo compare the extraction performance of solid-phase extraction (SPE), traditional solid-phase microextraction (SPME), and thin-film SPME (TF-SPME) in the determination of crude 4-ethylcyclohexylmethanol (MCHM) from environmental samples by gas chromatography with mass spectrometry detection (GC–MS). They exploit the rapid preconcentration features of TF-SPME, and report limits of quantitation for MCHM lower than any other reported method in the literature. The versatility of the approach is also demonstrated by determining a metabolite of MCHM through slight modifications to their procedure.

In a demonstration of the growing importance that metal-organic frameworks (MOFs) play in sample preparation, Veronica Pino and co-workers at the University of La Laguna in Spain describe the use of MOFs in dispersive SPE for the determination of personal care products by GC–MS. Many of the previously published approaches using MOF-based materials have been coupled to liquid chromatography. This study showcases the growing importance that MOFs can play as selective sorbent materials when coupled to GC applications.

Amid growing concerns about the release of extractables and leachables during the storage of pharmaceutical drugs, Leandro Hantao and co-workers at the State University of Campinas (Unicamp) in Brazil report a method using SPME coupled to comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC–MS). Their approach consists of direct immersion sampling from a nasal drug solution, and reveals four leachables identified by principal component analysis. Flow modulated GC×GC was employed as a more economical and user friendly alternative to thermal modulation for pharmaceutical analysis.

In an effort to monitor the chiral composition and enantiomeric excess of peach aroma, Cecilia Cagliero and co-workers at the University of Torino in Italy demonstrate a fully automated method based on stir-bar sorptive extraction (SBSE) followed by chiral GC–MS. The components γ- and ∂-lactone were quantified in natural and artificial peach flavored juices. The consolidated approach demonstrates the coupling of a highly sensitive sampling approach with chiral chromatography to achieve rapid quality control metrics of food products.

Last but not least, Javier Hernández-Borges and co-workers, also at the University of La Laguna, discuss the role of nanomaterials in sample preparation. They provide a comprehensive review of sorbent nanomaterials based on carbon, MOFs, covalent organic frameworks, nanoparticles, quantum dots, nanofibers, and dendrimers. Their article highlights some of the challenges and opportunities associated with the preparation, characterization, and toxicity of nanomaterials used in sample preparation.

Jared L. Andersonis a professor of chemistry at Iowa State University in Ames, Iowa. Direct correspondence to: andersoj@iastate.edu