Headspace stir bar sorptive extraction followed by thermal desorption and gas chromatography with mass spectrometry to determine musk fragrances in sludge samples without sample pretreatment

A direct, simple and solvent‐free method based on headspace stir bar sorptive extraction and thermal desorption gas chromatography with mass spectroscopy was developed to determine 13 musk fragrances (six polycyclic musks, three nitro musks and four macrocyclic musks) in sludge without sample treatment. The optimal headspace stir bar sorptive extraction conditions were achieved when a polydimethylsiloxane stir bar was exposed for 45 min in the headspace of a 10 mL vial filled with 100 mg of sludge mixed with 0.2 mL of water stirred at 750 rpm at 80°C. The stir bar was then desorbed in the thermal desorption gas chromatography and mass spectrometry system, obtaining limits of detection between 5 and 30 ng/g. The method applicability was tested with sewage sludge from two urban wastewater treatment plants and from a potable water treatment plant. Results showed galaxolide and tonalide to be the most abundant musk fragrances found in wastewater treatment plants with maximal concentrations of 9240 and 7500 ng/g, respectively. Maximum concentration levels between 35 and 635 ng/g were found for musk ketone, musk moskene, traseolide, phantolide and celestolide in this kind of samples. Concentrations below the limits of quantitation of phantolide, galaxolide, tonalide and musk ketone were found in sludge from a potable water treatment plant.     

Novel modified carbon nanotubes as a selective sorbent for preconcentration and determination of trace copper ions in fruit samples

In this work, multiwalled carbon nanotubes were reacted with N‐[3‐(triet‐hoxysilyl)propyl]isonicotinamide to prepare pyridine‐functionalized carbon nanotubes. This novel sorbent was characterized by infrared spectroscopy, thermal and elemental analysis, and scanning electron microscopy. Functionalized carbon nanotubes were applied for the preconcentration and determination of copper ions using flame atomic absorption spectrometry. Various parameters such as sample pH, flow rate, eluent type and concentration, and its volume were optimized. Under optimal experimental conditions, the limit of detection, the relative standard deviation, and the recovery of the method were 0.65 ng/mL, 3.2% and 99.4%, respectively. After validating the method using standard reference materials, the new sorbent was applied for the extraction and determination of trace copper(II) ions in fruit samples.     

Simultaneous determination of pharmaceuticals and some of their metabolites in wastewaters by high performance liquid chromatography with tandem mass spectrometry

The present work describes the development of a sensitive and reliable analytical method based on solid‐phase extraction followed by analysis using liquid chromatography with tandem mass spectrometry for the simultaneous determination of pharmaceuticals from antibiotics (fluoroquinolones, sulfonamides, and their N⁴‐acetyl metabolites, and trimethoprim as sulfonamides synergist) and anthelmintics groups. SPE was optimized using different cartridges (Strata‐X, Oasis HLB, Strata C₁₈‐E, Isolute C₁₈, SampliQ C₈/Si‐SCX). The highest recovery was achieved using Strata X cartridge (>80%) with good reproducibility (RSDs < 5%) despite various physicochemical properties of the compounds. Investigated analytes were identified and quantitatively determined by liquid chromatography with tandem mass spectrometry using multiple reaction monitoring. The method was shown to be linear over the concentration range of 0.05–30 μg/L for febantel and albendazole, and 0.10–60 μg/L for all other pharmaceuticals. Correlation coefficients were >0.99 for all compounds except for sulfamethazine (0.98). In order to demonstrate the applicability of the developed method, wastewater from the veterinary industry was analyzed. Results evidenced the presence of febantel, praziquantel, albendazole, enrofloxacin, sulfamethazine, and sulfadiazine.     

TiO2 nanotube arrays prepared by anodization as an adsorbent in micro‐solid‐phase extraction to preconcentrate and determine nitrogen‐containing polycyclic aromatic hydrocarbons in water samples

In this study, a simultaneous determination method for nitrogen‐containing polycyclic aromatic hydrocarbons including 7‐methylquinoline, acridine, 5,6‐benzoquinoline, carbazole, and 9‐methylcarbazole was developed. This method is based on a micro‐solid phase extraction using TiO₂ nanotube arrays as an adsorbent in combination with HPLC. Some factors that had an effect on the enrichment were optimized, such as sample pH, surfactant concentration, ion strength, type of eluent, equilibrium time, and desorption time. Under the optimized conditions, the linear ranges and LODs were in the range of 0.01–100 and 0.0035–0.81 μg/L, respectively. The precisions of the proposed method were <9.51% (RSD, n = 6). The developed method was validated with four real samples, and the spiked recoveries were in the range of 77–109.6%. All these results demonstrated that this novel micro‐solid‐phase extraction technique was a reliable alternative to conventional preconcentration method for the extraction and analysis of such nitrogen‐containing polycyclic aromatic hydrocarbons in complex samples.     

Miniaturized molecularly imprinted polymer extraction method for the gas chromatographic analysis of flavonoids

In this study, the use of monolithic molecularly imprinted polymers in a micropipette tip format allowing the simple and fast extraction of flavonoids from standard solutions and a black tea sample is demonstrated. The imprinted polymer employed quercetin, methacrylic acid or 4‐vinylpyridine, and ethylene glycol dimethacrylate as template, functional monomer, and cross‐linker, respectively. Surface morphologies of the quercetin‐imprinted polymers and the corresponding nonimprinted polymers were characterized by SEM. Extraction of flavonoid standards was performed to evaluate the selectivity and recovery with these imprinted and nonimprinted polymers. Flavonoid compositions in aliquots eluted from the tips were identified using fast GC with flame ionization detection. Maximum specific capacities of 0.2, 5.7, and 16.0 mg/g for catechin, morin, and quercetin, respectively, were obtained with the imprinted polymer prepared with methacrylic acid, with the corresponding recoveries of 99.8, 98.8, and 95.4%, respectively. Efficient extraction by the quercetin‐imprinted polymer of epicatechin, catechin, and quercetin from an apple‐flavored black tea sample was achieved, with GC–MS employed for compound identification for both the tea and extracted samples.     

Multiresidue determination of UV filters in water samples by solid‐phase extraction and liquid chromatography with tandem mass spectrometry analysis

UV filters, contained in sunscreens and other cosmetic products, as well as in some plastics and industrial products, are nowadays considered contaminants of emerging concern because their widespread and increasing use has lead to their presence in the environment. Furthermore, some UV filters are suspected to have endocrine disruption activity. In the present work, we developed an analytical method based on liquid chromatography with tandem mass spectrometry for the determination of UV filters in tap and lake waters. Sixteen UV filters were extracted from water samples by solid‐phase extraction employing graphitized carbon black as adsorbent material. Handling 200 mL of water sample, satisfactory recoveries were obtained for almost all the analytes. The limits of detection and quantification of the method were comparable to those reported in other works, and ranged between 0.7–3.5 and 1.9–11.8 ng/L, respectively; however in our case the number of investigated compounds was larger. The major encountered problem in method development was to identify the background contamination sources and reduce their contribution. UV filters were not detected in tap water samples, whereas the analyses conducted on samples collected from three different lakes showed that the swimming areas are most subject to UV filter contamination.     

A useful approach for the differentiation of wines according to geographical origin based on global volatile patterns

In this study, the feasibility of solid‐phase extraction combined with gas chromatography and mass spectrometry in tandem with partial least squares discriminant analysis was evaluated as a useful strategy to differentiate wines according to geographical origin (Azores, Canary and Madeira Islands) and types (white, red and fortified wine) based on their global volatile patterns. For this purpose, 34 monovarietal wines from these three wine grape‐growing regions were investigated, combining the high throughput extraction efficiency of the solid‐phase extraction procedure with the separation and identification ability. The partial least squares discriminant analysis results suggested that Madeira wines could be clearly discriminated from Azores and Canary wines. Madeira wines are mainly characterized by 2‐ethylhexan‐1‐ol, 3,5,5‐trimethylhexan‐1‐ol, ethyl 2‐methylbutanoate, ethyl dl ‐2‐hydroxycaproate, decanoic acid, 3‐methylbutanoic acid, and (E)‐whiskey lactone, whereas 3‐ethoxypropan‐1‐ol, 1‐octen‐3‐ol, (Z)‐3‐hexenyl butanoate, 4‐(methylthio)‐1‐butanol, ethyl 3‐hydroxybutanoate, isoamyl lactate, 4‐methylphenol, γ‐octalactone and 4‐(methylthio)‐1‐butanol, are mainly associated with Azores and Canary wines. The data obtained in this study revealed that solid‐phase extraction combined with gas chromatography and quadrupole mass spectrometry data and partial least squares discriminant analysis provides a suitable tool to discriminate wines, both in terms of geographical origin as well as wine type and vintage.     

Computer‐assisted design and synthesis of molecularly imprinted polymers for the simultaneous determination of six carbamate pesticides from environmental water

The computer‐assisted design and synthesis of molecularly imprinted polymers for the simultaneous capture of six carbamate pesticides from environmental water are reported in this work. The quantum mechanical computational approach was employed to design the molecularly imprinted polymers with carbofuran as template. The interaction energies between the template molecule and different functional monomers in various solvents were calculated to assist in the selection of the functional monomer and porogen. The optimised molecularly imprinted polymer was subsequently used as a class‐selective sorbent in solid‐phase extraction for pre‐concentration and determination of carbamates from environmental water. The parameters influencing the extraction efficiency of the molecularly imprinted solid‐phase extraction procedure were systematically investigated to facilitate the class‐selective extraction. For the proposed method, linearity was observed over the range of 2–500 ng/mL with the correlation coefficient ranging from 0.9760 to 1.000. The limits of detection ranged from 0.2 to 1.2 ng/mL, and the limit of quantification was 4 ng/mL. These results confirm that computer‐assisted design is an effective evaluation tool for molecularly imprinted polymers synthesis, and that molecularly imprinted solid‐phase extraction can be applied to the simultaneous analysis of carbamates in environmental water.     

Evaluation of alternative solvents for improvement of oil extraction from rapeseeds

This present study was designed to evaluate the performances of five alternative solvents (alcohols: ethanol, isopropanol and terpenes: d-limonene, α-pinene, p-cymene) compared to n-hexane in rapeseed oil extraction. The extracted oils were quantitatively and qualitatively analyzed to compare the solvents’ performances in terms of kinetics, fatty acid compositions, lipid yields, and classes. Moreover, micronutrients in extracted oils were also respectively quantified by high-performance liquid chromatography (HPLC) and gas chromatography (GC). In addition, the interactions between alternative solvents and rapeseed oil have been theoretically studied with the Hansen solubility methodology to get a better comprehension of dissolving mechanisms. The results indicated that p-cymene could be the most promising solvent for n-hexane substitution with higher lipid yield and good selectivity, despite the micronutrient contents were relatively low.     

Model-based equipment-design for plant-based extraction processes – considering botanic and thermodynamic aspects

The growing demand for plant-based products in the food, cosmetics and pharmaceutical industry leads to the need for a systematic process and equipment-design for the potentially applicable extraction techniques. Therefore, in this article, the classification of plant-based raw materials according to their characteristics is discussed. Furthermore, physicochemical modelling via distributed plug flow approach is applied and its possible fields of application are examined. Here, especially the extraction of water from the plant-based raw material as well as the entailed effects on the equilibrium and the mass transport kinetics are concerned. In addition to that, an evaluation method for the examined and generally available equipment through spider diagram is proposed. The relation to the initially argued botanic systems is discussed in particular. The extraction of vanillin from vanilla beans serves as exemplary system for this.