Current Chromatography - Volume 1, Issue 2, 2014

Chiral separation at nano scale is gaining importance in drugs development, proteomic, genomic and environmental sciences. Generally, traces of drugs are found in our body for several weeks. These cannot be detected by conventional analytical techniques. The present article discusses the advances in chiral resolution at nano scale using nano liquid chromatography (NLC) and nano capillary electrophoresis (NCE). The instrumentation, chiral selectors, mechanisms of chiral recognition and future challenges and prospectives have been discussed.

Ion chromatography was first introduced in 1975. Since then, it has been applied in most areas of the analytical chemistry. It is an effective technique used to analyze various inorganic and organic ions present in samples with different matrices. Importantly, ion chromatography has almost completely replaced the classical methods of ion determination. Its main advantages include: short analysis time; analysis of small volume samples; high sensitivity and selectivity; simultaneous separation and determination of different ions or ions of the same element at different oxidation states. As a result, it is routinely used to investigate ionic compounds in water, air and soil samples. The most important objectives of the ion chromatography improvement are to develop new stationary phases and enhance the peak capacity with complex eluent profiles. It is also essential to devise new methods of sample preparation and implementation of the hyphenated methods. In order to establish lower permissible limits for more and more ionic contaminants, researchers will need methods that are more accurate. For that reason, ion chromatography will continue to develop and become an even more valuable tool in the future. The following paper briefly describes the history, principles, development and applications of ion chromatography.

This article reviews the most recent and significant advances in headspace gas chromatography (HS-GC). The evolution and potential industrial applications in the last five years (2008 to present) are reviewed and discussed. The topics include a brief overview of the recent advances in HS-GC techniques and theory, followed by examples of new applications and instrumentation for the different headspace analysis techniques. The three main techniques of headspace sampling such as static, dynamic, and solid-phase microextraction (SPME) are described and a discussion of their advantages and limitations is included. Different designs of headspace devices, coupled techniques and chemometric data treatments used in HS-GC analysis are also briefly described. The potential industrial applications include environmental, clinical, materials, biological, food, flavour and pharmaceutical analysis. This report clearly illustrates that research in HS-GC is very active and growing, with new applications being reported regularly.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitary contaminants, which constitute a wide range of organic compounds. Many of them proved to be carcinogenic and mutagenic, produced mainly by industrial and non-industrial combustion processes, but also are present in water, air, soil, and as contaminants in foods, and beverages. Several industrial processes and artificial human activities can increase naturally environmental levels of these ubiquitary compounds, thereby increasing the levels of detected PAHs in final alimentary products. This paper reports PAHs extraction and detection techniques in beverages, including the analysis of beer, wine, spirits, tea, and coffee and, more generally, the standard drinks intended for human consumption. The state of the art in terms of sample pre-treatment techniques, and the main assays for their analysis by gas chromatography (GC) and high performance liquid chromatography (HPLC), with relative detection techniques, are described and catered. Moreover, major metabolites were determined in beverages, in order to provide a complete scenario for these kinds of ubiquitary contaminants.

Since the development of chiral stationary phases (CSPs), liquid chromatography has emerged as one of the most useful methods for analyses and preparation of enantiomerically pure bioactive compounds. However, the key for success of enantioseparation lies in the first place in the choice of a suitable CSP having enantioselectivity for the target enantiomers. Thus, this work describes a comparative study of resolution of seven chiral derivatives of xanthones (CDXs) on nine CSPs of different nature (four macrocyclic antibiotics, two Pirkle-type and three polysaccharide-based), under multimodal elution conditions. The polysaccharide-based CSPs have proved to be most suitable to separate this group of compounds, since all the CDXs were enantioseparated with excellent enantioselectivity and resolution. Six of the seven CDXs were separated on macrocyclic antibiotic-based CSPs, however with low enantioresolution. The Pirkle-type CSPs exhibited specificity on chiral discrimination behavior, presenting very high enantioselectivity for CDXs with aromatic group linked to the chiral moiety. This comparative study provides valuable information in the field of enantioresolution, and constitutes a useful background for subsequent studies of this important class of compounds.

A sensitive, precise and environmentally friendly stability indicating Rapid Resolution Liquid Chromatographic (RRLC) method for the determination of valaciclovir HCl in presence of its degradation products was developed and validated. An isocratic separation was achieved using Zorbax SB phenyl column with flow rate of 0.3 mL min-1 and UV detection at 254 nm. The mobile phase was a mixture of 0.01M n-tetrabutyl ammonium hydrogen sulfate (pH 2.5, adjusted using 0.1M NaOH) and methanol in the ratio of (95:5, v/v). The stability of valaciclovir HCl has been studied under different stress conditions. The acid-and alkaline-hydrolysis products were identified and were suggested to be guanine and aciclovir, respectively. Complete separation of valaciclovir hydrochloride and its degradation products was achieved in overall run time of approximately 6.0 min with low mobile phase consumption and waste production (1.8ml/run). The method was linear over the range of 0.4 'g mL-1 to 40.0 'g mL-1 (r=0.9999) with limit of detection and quantitation of 0.10 'g mL-1 and 0.36 'g mL-1, respectively. The high efficiency and unique selectivity of developed method enabled its adoption for determination of aciclovir, the active metabolite of valaciclovir, in spiked human plasma.