Enantioselectivity in the toxicological effects of chiral pesticides: A review

As a special category of pesticides, chiral pesticides have increased the difficulty in investigating pesticide toxicity. Based on their usage, chiral pesticides can be divided into insecticides, herbicides, and fungicides. Over the past decades, great efforts have been made on elucidating their toxicological effects. However, no literature has reviewed the enantioselective toxicity of chiral pesticides since 2014. In recent years, more chiral pesticides have been registered for application. As such, huge research progresses have been achieved in enantioselective toxicity of chiral pesticides. Generally, more researches have remedied the knowledge gap in toxicological effects of old and new chiral pesticides. And the toxicological endpoints being evaluated have become more specific rather than centering on basic toxicity and target organisms. Besides, the underlying mechanisms accounting for the enantioselectivity in toxicological effects of chiral pesticides have been discussed as well. All in all, this review provides the critical knowledge for risk assessments, and help to drive the green-technology of single- or enriched-enantiomer pesticides and formulation of relevant laws and regulations.

Supercritical Fluid Extraction of Pesticides and Insecticides from Food Samples and Plant Materials

The principal intention of this study is presenting the attempts carried out for extracting, separating, and determining of the pesticide and insecticide residues existing in food and plant samples. In this regard, a set of content, including the explanations about the supercritical fluid extraction (SFE), supercritical fluid chromatography, and various types of pesticides are indicated. Besides, the parameters affecting the pesticides extraction composed of temperature, pressure, modifier, drying agent, and so on are discussed. Also, examples of insecticides extraction by SFE technique as an important subset of pesticides are indicated. Along with these items, some interesting works, concerning the innovations implemented in the field of SFE of pesticide and insecticide residues from foodstuff and plants are depicted.

Green and sensitive supercritical fluid chromatographic-tandem mass spectrometric method for the separation and determination of flutriafol enantiomers in vegetables, fruits, and soil

A green and sensitive chiral analytical method was developed to determine flutriafol enantiomers in vegetables (tomato, cucumber), fruits (apple, grape), and soil by supercritical fluid chromatography-tandem mass spectrometry. The enantioseparation was performed within 3.50 min using Chiralpak IA-3 column with CO2/methanol (88:12, v/v) as the mobile phase at a 2.2 mL/min flow rate. The postcolumn compensation technology provided with 1% formic acid/methanol greatly improved the ionization efficiency of mass spectrometry. Column temperature, auto back pressure regulator pressure, and flow rate of compensation solvent were optimized to 30 °C, 2200 psi, and 0.1 mL/min, respectively. The simple and fast QuEChERS pretreatment method was adopted. Mean recoveries for flutriafol enantiomers were 77.2-98.9% with RSDs ≤ 9.6% in all matrices. The limits of quantification ranged from 0.41 to 1.18 μg/kg. Well-applied to analyze authentic samples, the developed method could act as a versatile strategy for the analysis of flutriafol enantiomers in food and environmental matrices.

Chiral separation of G-type chemical warfare nerve agents via analytical supercritical fluid chromatography

Chemical warfare nerve agents (CWNAs) are extremely toxic organophosphorus compounds that contain a chiral phosphorus center. Undirected synthesis of G-type CWNAs produces stereoisomers of tabun, sarin, soman, and cyclosarin (GA, GB, GD, and GF, respectively). Analytical-scale methods were developed using a supercritical fluid chromatography (SFC) system in tandem with a mass spectrometer for the separation, quantitation, and isolation of individual stereoisomers of GA, GB, GD, and GF. Screening various chiral stationary phases (CSPs) for the capacity to provide full baseline separation of the CWNAs revealed that a Regis WhelkO1 (SS) column was capable of separating the enantiomers of GA, GB, and GF, with elution of the P(+) enantiomer preceding elution of the corresponding P(-) enantiomer; two WhelkO1 (SS) columns had to be connected in series to achieve complete baseline resolution. The four diastereomers of GD were also resolved using two tandem WhelkO1 (SS) columns, with complete baseline separation of the two P(+) epimers. A single WhelkO1 (RR) column with inverse stereochemistry resulted in baseline separation of the GD P(-) epimers. The analytical methods described can be scaled to allow isolation of individual stereoisomers to assist in screening and development of countermeasures to organophosphorus nerve agents.

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).