Enantioselective separation of (±)-ß-hydroxy-1,2,3-triazoles by supercritical fluid chromatography and high-performance liquid chromatography.

This paper reports the enantioseparation of ß-hydroxy-1,2,3-triazole derivatives, which present a broad range of biological properties, by supercritical fluid chromatography (SFC) and high-performance liquid chromatography techniques (HPLC). Polysaccharide-based chiral columns (cellulose and amylose) were used to evaluate the separation in SFC and HPLC. Time of analyses, consumption of solvent, and parameter optimization were reduced using SFC technique. The columns based on cellulose chiral stationary phase using 2-propanol and ethanol as modifiers showed the best results for the enantioresolution of the (±)-ß-hydroxy-1,2,3-triazoles by SFC analyses. These techniques were applied to evaluate the selectivity of biocatalytic reduction of ß-keto-1,2,3-triazoles by marine-derived fungus Penicillium citrinum CBMAI 1186 to obtain the (±)-ß-hydroxy-1,2,3-triazoles.

Recent approaches for on-line analysis of residues and contaminants in food matrices: A review.

This review highlights recent developments for on-line determination of residues and contaminants in complex matrices such as food samples. This involves the on-line coupling of a sample preparation technique (as the first "dimension") with a chromatographic system (second "dimension"), usually followed by mass spectrometry. Although frequently treated as quite distinct techniques, the role of all devices utilized as the first dimension in this approach aims to decrease the sample complexity while eliminating as much as possible the matrix contaminants to facilitate the qualitative and quantitative determination of the compounds of interest. This review will focus on the following techniques as the first dimension: (i) on-line solid-phase extraction; (ii) in-tube solid-phase microextraction; (iii) matrix solid-phase dispersion; and (iv) turbulent flow chromatography. The second dimension is usually performed using a chromatographic column to isolate the analyte(s) of interest for further mass spectrometry determination. A description of the basis of this on-line approach and its distinct set up possibilities is presented, which is followed by a critical review of the literature covering this subject in the last ten years (focusing on the last five years) with emphasis on the analysis of residue and contaminants in food samples.

High resolution magic angle spinning NMR as a tool for unveiling the molecular enantiorecognition of omeprazole by amylose-based chiral phase.

Polysaccharide-based chiral stationary phases (CSP) demonstrate great versatility and higher chiral selectivity for a variety of chiral compounds in multimodal elution modes (normal, reverse and polar organic). The main role of CSP phenyl carbamate based derivatives as chiral selectors is the formation of diastereoisomeric complexes by means of π-π interaction, dipole-dipole, hydrogen bonding and/or inclusion complex mechanisms. Nevertheless, the mechanism behind their enantioselectivity requires clarification. High resolution magic angle spinning nuclear magnetic resonance spectroscopy ((1)H HR/MAS NMR) has provided key information on the recognition process at the binding sites of the CSP surface. Herein we report the results obtained using omeprazole as a probe for these investigations.

Multimilligram enantioresolution of sulfoxide proton pump inhibitors by liquid chromatography on polysaccharide-based chiral stationary phase.

The enantiomers of sulfoxide proton pump inhibitors--omeprazole, lansoprazole, rabeprazole and Ro 18-5364--were enantiomerically separated by liquid chromatography at multimilligram scale on a polysaccharide-based chiral stationary phase using normal and polar organic conditions as mobile phase. The values of the recovery and production rate were significant for each enantiomer; better results were achieved using a solid-phase injection system. However, this system was applied just for the enantiomeric separation of omeprazole to demonstrate the applicability of this injection mode at milligram scale. The chiroptical characterization of the compounds was performed using a polarimeter and a circular dichroism detector. The higher enantiomeric purity obtained for the isolated enantiomers suggests that the methods here described should be considered as a simple and rapid way to obtain enantiomeric pure standards for analytical purpose.

Bioanalytical challenge: A review of environmental and pharmaceuticals contaminants in human milk.

An overview of bioanalytical methods for the determination of environmental and pharmaceutical contaminants in human milk is presented. The exposure of children to these contaminants through lactation has been widely investigated. The human milk contains diverse proteins, lipids, and carbohydrates and the concentration of these components is drastically altered during the lactation period providing a high degree of an analytical challenge. Sample collection and pretreatment are still considered the Achilles' heel. This review presents liquid chromatographic methods developed in the last 10 years for this complex matrix with focuses in the extraction and quantification steps. Green sample preparation protocols have been emphasized.

Direct injection of native aqueous matrices by achiral-chiral chromatography ion trap mass spectrometry for simultaneous quantification of pantoprazole and lansoprazole enantiomers fractions.

A two-dimensional liquid chromatography system coupled to ion-trap tandem mass spectrometer (2DLC-IT-MS/MS) was employed for the simultaneous quantification of pantoprazole and lansoprazole enantiomers fractions. A restricted access media of bovine serum albumin octyl column (RAM-BSA C(8)) was used in the first dimension for the exclusion of the humic substances, while a polysaccharide-based chiral column was used in the second dimension for the enantioseparation of both pharmaceuticals. The results described here show good selectivity, extraction efficiency, accuracy, and precision with detection limits of 0.200 and 0.150 µg L(-1) for the enatiomers of pantoprazole and lansoprazole respectively, while employing a small amount (1.0 mL) of native water sample per injection. This work reports an innovative assay for monitoring work, studies of biotic and abiotic enantioselective degradation and temporal changes of enantiomeric fractions.

Spatiotemporal distribution of pharmaceuticals in the Douro River estuary (Portugal).

The amount and distribution of six pharmaceutical compounds belonging to distinct therapeutic classes were investigated along the navigation channel of the Douro River estuary. Distinct spatial and temporal trends were considered and a total of 87 water samples were pre-concentrated by solid-phase extraction (SPE) and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) with an ion trap (IT) analyzer and electrospray ionization (ESI). The maximum concentrations found were 178ng/L for carbamazepine, 3.65ng/L for diazepam, 70.3ng/L for fenofibric acid, 3.18ng/L for propranolol, 15.7ng/L for trimethoprim and 53.3ng/L for sulfamethoxazole. Carbamazepine was the most ubiquitous compound with 100% positive detection frequency followed by propranolol (38%), trimethoprim (34%) and sulfamethoxazole (33%). The pharmaceutical compounds were quantified at higher levels in the lower stretch of the estuary, especially near the wastewater treatment plant (WWTP). The data proves that pollution of the Douro River estuary by pharmaceuticals is consistent and is occurring in a fairly constant manner in time, covering a wide area and displaying hot-spots. Individually, the concentration levels are not likely to cause acute effects, based on reference experimental data. However, the fact that complex mixtures exist gives cause for concern as regards potentially relevant toxicological risks. The study points out the need for continuous monitoring of contamination levels not only in the Douro River estuary but also in other major estuaries. Finally, the scenario supports the need for experimental studies on toxicological impacts on aquatic organisms at environmentally relevant concentrations.

A column-switching method for quantification of the enantiomers of omeprazole in native matrices of waste and estuarine water samples.

This work reports the use of a two-dimensional liquid chromatography (2D-LC) system for quantification of the enantiomers of omeprazole in distinct native aqueous matrices. An octyl restricted-access media bovine serum albumin column (RAM-BSA C(8)) was used in the first dimension, while a polysaccharide-based chiral column was used in the second dimension with either ultraviolet (UV-vis) or ion-trap tandem mass spectrometry (IT-MS/MS) detection. An in-line configuration was employed to assess the exclusion capacity of the RAM-BSA columns to humic substances. The excluded macromolecules had a molecular mass in the order of 18 kDa. Good selectivity, extraction efficiency, accuracy, and precision were achieved employing a very small amount (500 microL or 1.00 mL) of native water sample per injection, with detection limits of 5.00 microg L(-1), using UV-vis, and 0.0250 microg L(-1), using IT-MS/MS. The total analysis time was only 35 min, with no time spent on sample preparation. The methods were successfully applied to analyze a series of waste and estuarine water samples. The enantiomers were detected in an estuarine water sample collected from the Douro River estuary (Portugal) and in an influent sample from the wastewater treatment plant (WWTP) of São Carlos (Brazil). As far as we are concerned, this is the first report of the occurrence of (+)-omeprazole and (-)-omeprazole in native aqueous matrices.

Restricted-access media supports for direct high-throughput analysis of biological fluid samples: review of recent applications.

This review presents an update on the use of restricted-access materials (RAMs) for direct injection of biological samples. The fundamental improvements in the preparation of tailored RAMs and the diversity of applications with these phases are presented. Insights into diminishing the matrix effect by the use of RAM supports in methods by LC-MS and into the low number of methods for enantiomeric separations by direct injections of biological samples are addressed. The diversity of systems that incorporate RAMs for selective sample clean-up or fractionation in proteome and peptidome analysis is also covered.

Pharmaceutical trace analysis in aqueous environmental matrices by liquid chromatography-ion trap tandem mass spectrometry.

An analytical method based on solid-phase extraction followed by liquid chromatography tandem mass spectrometry with an ion trap analyser was developed and validated for the quantification of a series of pharmaceutical compounds with distinct physical-chemical characteristics in estuarine water samples. Method detection limits were between 0.03 and 16.4 ng/L. The sensitivity and the accuracy obtained associated with the inherent confirmatory potential of ion trap tandem mass spectrometry (IT-MS/MS) validates its success as an environmental analysis tool. Two MS/MS transitions were used to confirm compound identity. Almost all pharmaceuticals were detected at ng/L level in at least one sampling site of the Douro River estuary, Portugal.