Chiral Resolution of Racemic Environmental Pollutants by Capillary Electrophoresis

Pair of chiral 2D silver(I) enantiomers: chiral recognition of L- and D-histidine via differential pulse voltammetry

Self-assembly of AgPF₆ with a pair of chiral tridentate ligands (1S,1'S,1''S,2R,2'R,2''R) and (1R,1'R,1''R,2S,2'S,2''S)-(benzenetricarbonyltris(azanediyl))tris(2,3-dihydro-1H-indene-2,1-diyl)triisonicotinate (s,r-L) and (r,s-L) in a mixture of methanol and dioxane yields 2D sheets consisting of [Ag(s,r-L)](PF₆)·3C₄H₈O₂·0.5H₂O and [Ag(r,s-L)](PF₆)·3C₄H₈O₂·0.5H₂O, respectively. The differential pulse voltammetric (DPV) technique using the pair of chiral 2D-sheet enantiomers was employed for chiral discrimination of amino acid enantiomers, and was found to be an effective tool for enantio-recognition of L- and D-histidines. Both the size and the binding site of amino acids were strongly dependent on electrochemical enantio-recognition via the chiral 2D sheets.

Chiral Pesticides with Asymmetric Sulfur: Extraction, Separation, and Determination in Different Environmental Matrices

Chiral pesticides with S atoms as asymmetric centers are gaining great importance in the search for new pesticides with new modes of action. As for the rest of the chiral pesticides, the determination of the stereoisomers separately has become crucial in the environmental risks assessment of these pesticides. Therefore, the development of suitable extraction and clean-up methods as well as efficient stereoselective analytical techniques for stereoisomers determination in environmental samples is essential. Currently, liquid/solid phase extraction, microextraction, and QuEChERS-based methods are most commonly used to obtain chiral pesticides from environmental samples. Gas, liquid, and supercritical fluid chromatography together with capillary electrophoresis techniques are the most important for the determination of the stereoisomers of chiral pesticides containing S atoms in its structure. In this study, all these techniques are briefly reviewed, and the advantages and disadvantages of each are discussed

Developing, optimizing, and assessing a green electrophoretic method for determination of benzbromarone and allopurinol with its active metabolite in biological and pharmaceutical matrices

A combination of allopurinol and benzbromarone is a common gout treatment protocol. A suboptimal response to allopurinol in patients is very common due to its pharmacokinetics variability. Moreover, the safe doses of benzbromarone is very crucial in patients with hepatic diseases. This raised the inquisitiveness to develop and optimize a capillary zone electrophoresis method for the determination of allopurinol and benzbromarone in their coformulation and in the presence of oxypurinol, the active metabolite of allopurinol, in biological and pharmaceutical matrices. The method greenness profile was assessed using green metric tools the "National Environmental Method Index," the "Analytical Eco-Scale," and the "Green Analytical Procedure Index" by which the method proved to be ecofriendly. The method was successfully applied for the analysis of the pharmaceutical preparation and urine samples spiked with both drugs and the active metabolite. The linearity range was 25.0-250.0 μg/mL for benzbromarone, 50.0-350.0 μg/mL for allopurinol, and 100.0-500.0 μg/mL for oxypurinol. The recoveries were 99.60 ± 0.67, 99.89 ± 0.98, and 98.71 ± 1.18% for benzbromarone, allopurinol, and oxypurinol, respectively. The analysis results indicate potential usefulness of capillary zone electrophoresis as a competitive and greener method of analysis in biological and quality control labs.

Advances in Chiral Separations at Nano Level

Background::

Nano level chiral separation is necessary and demanding in the development of the drug, genomic, proteomic, and other chemical and the environmental sciences. Few drugs exist in human body cells for some days at nano level concentrations, that are out of the jurisdiction of the detection by standard separation techniques. Likewise, the separation and identification of xenobiotics and other environmental contaminants (at nano or low levels) are necessary for our healthiness.

Discussion:

Conclusion:

This article will be beneficial for chiral chromatographers, academicians, pharmaceutical industries, environmental researchers and Government regulation authorities.

Chemical chiral pollution: Impact on the society and science and need of the regulations in the 21st century

The chiral pollution is a serious issue for our health and environment due to the enantio-selective biodegradation of the chiral pollutants. It has adverse impact on our society and science. There is a big loss of our economy due to the use of racemic agrochemicals. The most notorious chiral pollutants are pesticides, polychloro biphenyls, polyaromatic hydrocarbons, brominated flame retardants, drugs, and pharmaceuticals. More than 1500 chiral pollutants are present in the environment. Unfortunately, there is no regulation and control of the chiral pollutants. Therefore, it is an urgent need of the present 21st century to develop a data bank on the chiral pollutants, guidelines for controlling the production, sale and use of the racemic agrochemicals and the other industrial products. The Governments of the different countries should come forward to initiate the regulations. US, FDA, US EPA, and WHO are the most important regulatory authorities and should think about the chiral pollutants. The present article highlights the impact of the chiral pollution on the society and science. Besides, the efforts have also been made to emphasize the need of the regulations to control the chiral pollution.

Recentchiral selectors for separation in HPLC and CE

Enantiomers (stereoisomers) can exhibit substantially different properties if present in chiral environments. Since chirality is a basic property of nature, the different behaviors of the individual enantiomers must be carefully studied and properly treated. Therefore, enantioselective separations are a very important part of separation science. To achieve the separation of enantiomers, an enantioselective environment must be created by the addition of a chiral selector to the separation system. Many chiral selectors have been designed and used in various fields, such as the analyses of drugs, food constituents and agrochemicals. The most popular have become the chiral selectors and/or chiral stationary phases that are of general use, i.e., are applicable in various separation systems and allow for chiral separation of structurally different compounds. This review covers the most important chiral selectors / chiral stationary phases described and applied in high performance liquid chromatography and capillary electrophoresis during the period of the last three years (2008–2011).

Chiral separations

The main goal of this review is to provide a brief overview of chiral separations to researchers who are versed in the area of analytical separations but unfamiliar with chiral separations. To researchers who are not familiar with this area, there is currently a bewildering array of commercially available chiral columns, chiral derivatizing reagents, and chiral selectors for approaches that span the range of analytical separation platforms (e.g., high-performance liquid chromatography, gas chromatography, supercritical-fluid chromatography, and capillary electrophoresis). This review begins with a brief discussion of chirality before examining the general strategies and commonalities among all of the chiral separation techniques. Rather than exhaustively listing all the chiral selectors and applications, this review highlights significant issues and differences between chiral and achiral separations, providing salient examples from specific classes of chiral selectors where appropriate.