Current Chromatography - Volume 5, Issue 2, 2018

Background: Since the 1990s, technical developments and theoretical studies of columns packed with core-shell and sub-core-shell particles demonstrated improved efficiency separation, time reduction, solvent use than fully porous columns. Thanks to this chromatographic system, environmental pollutants are being analysed under green conditions. Objective: This paper presents theoretical aspects and a review of the main features of core-shell technology focusing essentially on environmental applications. Method: The main advantages of core-shell columns may be summarized as follows: i) reduction of the eddy dispersion A term; ii) homogeneity of the particle size distribution reducing the velocity bias; (iii) superior mass transfer kinetics; iv) better performance of the separation (faster and greater). Results: Systematic comparisons with fully porous particles undeniably highlighted the benefits of core-shell technology in the separation of a great number of pollutants and “micropollutants” of different molecular weights which surround us and have an impact on the ecosystem. Conclusion: Core-shell particles are emerging as green substrates for the analysis of chemical species problematic for environment. The environmental gain in terms of limitation of analysis time and solvent consumption has been demonstrated. The current manuscript proposes an update of the literature devoted to the use of core-shell particles in environmental applications. Future trends in the field and the expectations of the scientific community are also described since increasing attention is being paid to the detection of environmental pollutants.

Different nanoparticles have successfully been used in laboratory, pilot and field scale for degradation of organic dangerous pollutants during the last decades. In fact, nanotechnology will, in the near future, play a key role in soil and ground/wastewater decontamination chemical processes. However, since many of the developed techniques for this purpose are still at an experimental or pilot stage, there is a need to demonstrate their large-field scale rather than laboratory effectiveness, i.e. to show they are safe, the reaction proceeds at satisfactory rates and the remediation of target compounds achieved. Good reproducibility, robustness, and the knowledge of generated by-products are also relevant parameters to be defined. To accomplish these goals, suitable methods should be used for the qualitative and quantitative analysis of target compounds and their byproducts. The aim of this work is to review the analytical methods used in nanoparticles remediation processes for the monitoring of organic contaminants in matrixes such as soils, sediments and water. To this end, previous works were examined and classified according to the chemical nature of the most frequent compounds involved in remediation studies: volatile and semi-volatile organic compounds and, among them, halogenated and non-halogenated solvents, pesticides, explosives and polycyclic aromatic hydrocarbons. Although gas and liquid chromatography are analytical methods highly often used for monitoring these compounds, only a few works validate their methodology. Consequently, taking into account the results of this overview, analytical methods based on headspace analysis coupled with gas chromatography-mass spectrometry are suggested as a future perspective in remediation procedures with nanoparticles.

Background: Dehydroleucodine is a sesquiterpene lactone isolated from Artemisia douglasiana Besser. Distinctive biological and pharmacological activities have been shown extensively for this molecule. Only one analytical method has been described for the quantification of dehydroleucodine in biological experimental systems. However, this assay involves fluorescent detection that is normally not recommended for routine analysis. Objective: The goal of this study was to develop and validate a novel methodology for rapid detection and quantitation of dehydroleucodine by HPLC with UV detection. Method: The method involved the use of a C18 separation column, an acetonitrile/water (80:20, v/v) solution as a mobile phase in an isocratic mode at a flow rate of 1 ml/min, and UV detection at 254 nm. Results: In the selected experimental conditions, dehydroleucodine exhibited a well-defined chromatographic peak with a retention time of 3.51 min. The chromatographic signal shows a linear dependence with the dehydroleucodine concentration. Correlation coefficient: 0.99. LOD: 1.5 ng/mL. LOQ: 15 ng/mL. Conclusion: The current method is simpler, faster, and cheaper than the previously reported one, and besides it could be useful to quantify this lactone and related pharmacological compounds. Furthermore, quality control of medicinal extracts of plant origin could be analyzed, and the concentration of the active constituent could be certified by this method.

Background: Testing of hair samples for drugs of abuse is advantageous as compared to other complementary matrices like urine or blood, due to longer detection window, non-invasive, and easy storage conditions. Ethyl glucuronide (EtG) is a promising biomarker for the identification of alcohol abuse in doping control or forensic analysis. Objective: This paper introduces a fast and sensitive method for determination of EtG in human hair using liquid chromatography-tandem mass spectrometry (LC–MS/MS) as per ISO:IEC 17025/2005 guidelines. Methods: Hair strands (50 mg) were washed with dichloromethane for 5 minutes followed by methanol for 2 minutes. The extraction was performed using an ultrasonic incubation for 2 h. These samples were incubated overnight at ambient temperature. After incubation, again ultrasonicated for 2 minutes and then centrifuged at 3500 rpm for ten minutes. The supernatant was decanted & dried under nitrogen (N2). The obtained residue was reconstituted in 40 μl of 0.1% formic acid out of which, 20 μl of extract was injected into the LC-MS/MS system. Results: The best separation was achieved using a C-18 column and a mobile phase comprising of 0.1% formic acid: acetonitrile in a gradient mode, with flow rate and temperature being 0.6 ml/min and 30ºC, respectively. The run time of the developed method is 6 minutes. The LOD was obtained at 3 pg/mg and LOQ at 10 pg/mg. The linearity for quantification analysis was established from 10- 200 pg/mg. The coefficients of variation in intra- and inter-assay precision were always lower than 15%. The method was successfully applied and qualified for the quantitative determination of EtG in proficiency test (PT) samples received from the Society of Hair Testing (SoHT) for the year 2015 & 2016. Conclusion: This method proved to be fast and sensitive to detect EtG in human hair and would be useful in the field of doping control and forensic toxicology.

Background: Voriconazole (VORI), a derivative of fluconazole, shows a greater selectivity for the fungal enzyme than for the corresponding rat liver enzyme as compared to Ketoconazole and Itraconazole. Methods: An environment friendly, simple, rapid, and isocratic robust supercritical fluid chromatographic method has been developed and validated for determining Voriconazole (VORI) in Bulk drug and laboratory mixture representing the marketed dosage form. Efficient chromatographic separation was achieved on a SFC Packed Crest C18 T (150 4.0 mm, 5.0 μm) with mobile phase CO2, in isocratic combination with methanol (MeOH) 90: 10, respectively, at a flow rate of 1.0 mL/min; the eluent being monitored at 256 nm using UV-detector. The supercritical nature of carbon dioxide was maintained at 12 MPa pressure and 40°C temperature. Results: In the optimized method, the retention time of VORI was 3.5 minute. The test solution was found to be stable in the blank for 24 h. Robustness of the developed SFC method was optimized by varying chromatographic conditions viz. column oven temperature, flow rate, SFC temperature and pressure change. Conclusion: Regression analyses indicate correlation coefficient value greater than 0.997 for VORI in the linearity range of 100-400 μg/mL. The method had shown good, consistent recoveries for VORI (99.3-101.2%). The method was found to be accurate, precise, linear, specific, sensitive, rugged and robust.