Properties of Analytes/Matrices in Selection of Chromatographic Methods and Detection Techniques

Dear Colleagues,

Many modern analytical techniques are used in analyte residue analysis. The method selected depends on the complexity of the sample, the natures of the matrices and the analytes, and the analytical techniques available. The most efficient approach to analyte identification and quantitative analysis involves the use of chromatographic methods.

The following chromatographic methods are most frequently applied to the determination of analytes: high-performance liquid chromatography (HPLC), ultrahigh-performance liquid chromatography (UPLC), gas chromatography (GC) and multidimensional chromatographic techniques (GC x GC, LC x LC). These methods are used for the quantitative analysis of compounds in different matrices, e.g., environmental and biological samples, and food analysis.

The choice of an appropriate extraction and analytical method for separation and final determination is closely related to the properties of the target compounds and matrices. Common steps in the sample treatment for most of the analytical methods reported for mixtures of analytes include sample pretreatment, the extraction of analytes from the matrix, cleanup of the extracts to remove interference, and concentration to achieve the desired sensitivity. Incontestable progress has been made in the past years regarding the development of preparation techniques for sample analysis such as QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe), Solid Phase Extraction (SPE), Solid Phase Microextraction (SPME), Stir Bar Sorptive Extraction (SBSE), Hallow-Fiber Liquid Phase Microextraction (HFLPME), Dispersive Liquid-Liquid Microextraction (DLLME) or Focused Ultrasonic Solid-Liquid Extraction (FUSLE), and others.

The challenge for the analyst is to develop effective and validated analytical strategies for the analysis of hundreds of different analytes on hundreds of different sample types, quickly, accurately and at acceptable cost. HPLC or UPLC are the principal separation techniques in the analysis of almost all types of samples. For example, HPLC-DAD enables peak purity control and the group identification (or class identification) of analytes.

Sometimes the resolving power attainable with a single chromatographic system is insufficient for the analysis of complex mixtures. The coupling of chromatographic techniques is clearly attractive for the analysis of multicomponent mixtures of compounds. Analysis of the compounds present at low concentrations in complex mixtures is especially challenging because the number of interfering compounds present at similar or higher concentrations increases exponentially as the concentrations of target compounds decrease. Truly comprehensive 2-D hyphenation is generally achieved by frequent sampling from a first column into a second, which is a very rapid analysis. Multidimensional LC has long been seen as a potential solution to increase the resolution and improve the speed of analysis, particularly in the separation of complex mixtures, for example, pesticides in natural samples. Multidimensional LC methods are typically divided into two main groups: comprehensive separations (denoted LC × LC for a 2-D separation) concerned with the separation and quantification of large numbers (ca. tens to thousands) of constituents of a sample, and targeted “heart-cutting” or “coupled-column” methods (LC–LC for a 2-D separation) concerned with the analysis of a few (ca., 1–5) constituents of the sample matrix. In the past decade, research on the development of practically useful LC × LC has been particularly active. Multidimensional LC is a good alternative to multidimensional GC for polar or thermolabile compounds. Polar compounds need to be derivatized for GC analysis, and this is not necessary for LC.

This Special Issue will present in a properly structured manner up-to-date, state of the art information on the very important field of high-performance chromatographic techniques coupled with modern detection techniques (e.g., DAD, FLD, mass spectrometry (MS) or tandem mass spectrometry (MS/MS)). It is a well-established fact that chromatographic techniques with mass spectrometry (MS) or tandem mass spectrometry (MS/MS) find broad application in the separation, identification, and quantification of the majority of the important analytes.

I warmly invite colleagues to submit their original contributions to this Special Issue, which will be of interest to a wide range of our readers!

I would be delighted if you could respond to confirm your contribution and the proposed title by 30 June 2020 to assist in planning the whole project. In the cases of review articles an additional brief (1–2 pages) description of the topic including a draft index is required. This preliminary step is essential to avoid the overlapping of topics. The degree of novelty and the significance of the research will be scrutinized prior to the peer-reviewing process.

Dr. Tomasz Tuzimski (Ph.D., Adjunct Professor)
Guest Editor

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• analytes (basic, acidic, neutral, ionic, nonionic and others)
• extraction techniques (QuEChERS/d-SPE, SPE, SPME, SBSE, HFLPME, DLLME, FUSLE, and others)
• chromatographic methods (HPLC, UPLC, LC x LC, LC-LC, GC, GC x GC, GC-GC, and others)
• detection techniques (DAD, FLD, MS, MS/MS, and others).