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Special Issue "Microextraction"

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products".

Deadline for manuscript submissions: closed (15 April 2014)

Special Issue Editor

Guest Editor
Dr. Elefteria Psillakis (Website)

School of Environmental Engineering, Technical University of Crete, 73100 Chania-Crete, Greece
Interests: the development and application of novel analytical procedures for detecting trace amounts of organic pollutants in a variety of environmental samples; studying the fate of organic micropollutants in natural and engineered environments

Special Issue Information

Submission

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Keywords

  • sample preparation
  • sample preconcencentration
  • solid-phase microextraction; SPME
  • liquid-phase microextraction; LPME
  • hollow-fiber liquid phase microextraction; HF-LPME
  • single-drop microextraction; SDME
  • dispersive liquid-liquid microextraction; DLLME
  • stir-bar sorptive extraction
  • QuEChERS
  • solidified floating organic drop
  • emulsification
  • Vortex-assisted
  • environmental organic analysis;
  • emerging organic contaminants
  • remote sensing
  • pharmaceuticals
  • food analysis
  • natural products, flavor and fragrance analysis
  • biological sample preparation
  • biomedical applications
  • diagnostic tools
  • microfluidics

Published Papers (9 papers)

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Research

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Open AccessArticle The Use of Headspace Solid-Phase Microextraction (HS-SPME) to Assess the Quality and Stability of Fruit Products: An Example Using Red Mombin Pulp (Spondias purpurea L.)
Molecules 2014, 19(10), 16851-16860; doi:10.3390/molecules191016851
Received: 10 April 2014 / Revised: 18 June 2014 / Accepted: 27 June 2014 / Published: 21 October 2014
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Abstract
The present study aimed to evaluate the volatiles profile of red mombin (Spondias purpurea) pulp and its powder produced by spray-drying (SD) as an example to show utility of headspace solid-phase microextraction (HS-SPME) in the analysis of parameters such as [...] Read more.
The present study aimed to evaluate the volatiles profile of red mombin (Spondias purpurea) pulp and its powder produced by spray-drying (SD) as an example to show utility of headspace solid-phase microextraction (HS-SPME) in the analysis of parameters such as the quality and stability of fruit products. Volatiles profiles of the pulp were identified by gas chromatography-mass spectrometry (GC-MS), quantified by gas chromatography-flame ionization detector (GC-FID) and compared to the profile of the powder stored at 0, 60 and 120 days in plastic (PP) or laminated packages (LP). The results showed that the technique was able to identify 36 compounds in the red mombin pulp, 17 out of which have been described for the first time in this fruit, showing that red mombin fresh pulp appears to be unique in terms of volatiles composition. However, only 24 compounds were detected in the powder. This decrease is highly correlated (r2 = 0.99), at least for the majority of compounds, to the degree of volatility of compounds. Furthermore, the powder stored in PP or LP showed no statistical differences in the amounts of its components for a period of 120 days of storage. Finally, this work shows how HS-SPME analysis can be a valuable tool to assess the quality and stability of fruit products. Full article
(This article belongs to the Special Issue Microextraction)
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Open AccessArticle Second Order Kinetic Modeling of Headspace Solid Phase Microextraction of Flavors Released from Selected Food Model Systems
Molecules 2014, 19(9), 13894-13908; doi:10.3390/molecules190913894
Received: 16 April 2014 / Revised: 29 July 2014 / Accepted: 11 August 2014 / Published: 4 September 2014
Cited by 1 | PDF Full-text (1214 KB) | HTML Full-text | XML Full-text
Abstract
The application of headspace-solid phase microextraction (HS-SPME) has been widely used in various fields as a simple and versatile method, yet challenging in quantification. In order to improve the reproducibility in quantification, a mathematical model with its root in psychological modeling and [...] Read more.
The application of headspace-solid phase microextraction (HS-SPME) has been widely used in various fields as a simple and versatile method, yet challenging in quantification. In order to improve the reproducibility in quantification, a mathematical model with its root in psychological modeling and chemical reactor modeling was developed, describing the kinetic behavior of aroma active compounds extracted by SPME from two different food model systems, i.e., a semi-solid food and a liquid food. The model accounted for both adsorption and release of the analytes from SPME fiber, which occurred simultaneously but were counter-directed. The model had four parameters and their estimated values were found to be more reproducible than the direct measurement of the compounds themselves by instrumental analysis. With the relative standard deviations (RSD) of each parameter less than 5% and root mean square error (RMSE) less than 0.15, the model was proved to be a robust one in estimating the release of a wide range of low molecular weight acetates at three environmental temperatures i.e., 30, 40 and 60 °C. More insights of SPME behavior regarding the small molecule analytes were also obtained through the kinetic parameters and the model itself. Full article
(This article belongs to the Special Issue Microextraction)
Open AccessArticle Determination of Phenol Compounds In Surface Water Matrices by Bar Adsorptive Microextraction-High Performance Liquid Chromatography-Diode Array Detection
Molecules 2014, 19(7), 9369-9379; doi:10.3390/molecules19079369
Received: 13 March 2014 / Revised: 26 June 2014 / Accepted: 27 June 2014 / Published: 3 July 2014
Cited by 2 | PDF Full-text (277 KB) | HTML Full-text | XML Full-text
Abstract
Bar adsorptive microextraction combined with liquid desorption followed by high performance liquid chromatography with diode array detection (BAµE-LD/HPLC-DAD) is proposed for the determination of trace levels of five phenol compounds (3-nitrophenol, 4-nitrophenol, bisphenol-A, 4-n-octylphenol and 4-n-nonylphenol) in surface [...] Read more.
Bar adsorptive microextraction combined with liquid desorption followed by high performance liquid chromatography with diode array detection (BAµE-LD/HPLC-DAD) is proposed for the determination of trace levels of five phenol compounds (3-nitrophenol, 4-nitrophenol, bisphenol-A, 4-n-octylphenol and 4-n-nonylphenol) in surface water matrices. By using a polystyrene-divinylbenzene copolymer (PS-DVB) sorbent phase, high selectivity and efficiency is achieved even against polydimethylsiloxane through stir bar sorptive extraction. Assays performed by BAµE(PS-DVB)-LD/HPLC-DAD on 25 mL water samples spiked at the 10.0 µg/L levels yielded recoveries over 88.0% ± 5.7% for all five analytes, under optimized experimental conditions. The analytical performance showed good precision (RSD < 15%), detection limits of 0.25 µg/L and linear dynamic ranges (1.0–25.0 μg/L) with determination coefficient higher than 0.9904. By using the standard addition method, the application of the present method to surface water matrices allowed very good performances at the trace level. The proposed methodology proved to be a suitable alternative to monitor phenol compounds in surface water matrices, showing to be easy to implement, reliable, sensitive and requiring a low sample volume. Full article
(This article belongs to the Special Issue Microextraction)
Open AccessArticle Determination of Volatile Organic Compounds (VOCs) from Wrapping Films and Wrapped PDO Italian Cheeses by Using HS-SPME and GC/MS
Molecules 2014, 19(7), 8707-8724; doi:10.3390/molecules19078707
Received: 30 April 2014 / Revised: 18 June 2014 / Accepted: 19 June 2014 / Published: 25 June 2014
Cited by 2 | PDF Full-text (709 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Nowadays food wrapping assures attractive presentation and simplifies self-service shopping. Polyvinylchloride (PVC)- and polyethylene (PE)-based cling-films are widely used worldwide for wrapping cheeses. For this purpose, films used in retail possess suitable technical properties such as clinginess and unrolling capacity, that are [...] Read more.
Nowadays food wrapping assures attractive presentation and simplifies self-service shopping. Polyvinylchloride (PVC)- and polyethylene (PE)-based cling-films are widely used worldwide for wrapping cheeses. For this purpose, films used in retail possess suitable technical properties such as clinginess and unrolling capacity, that are achieved by using specific plasticizers during their manufacturing process. In the present study, the main VOCs of three cling-films (either PVC-based or PE-based) for retail use were characterized by means of Solid-Phase Micro-Extraction and GC/MS. In addition, the effects of cling film type and contact time on the migration of VOCs from the films to four different PDO Italian cheeses during cold storage under light or dark were also investigated. Among the VOCs isolated from cling-films, PVC released 2-ethylhexanol and triacetin. These compounds can likely be considered as a “non-intentionally added substance”. These same compounds were also detected in cheeses wrapped in PVC films with the highest concentration found after 20 days storage. The PE cling-film was shown to possess a simpler VOC profile, lacking some molecules peculiar to PVC films. The same conclusions can be drawn for cheeses wrapped in the PE cling-film. Other VOCs found in wrapped cheeses were likely to have been released either by direct transfer from the materials used for the manufacture of cling-films or from contamination of the films. Overall, HS-SPME is shown to be a rapid and solvent free technique to screen the VOCs profile of cling-films, and to detect VOCs migration from cling-films to cheese under real retail storage conditions. Full article
(This article belongs to the Special Issue Microextraction)
Open AccessArticle Volatile Fingerprint of Italian Populations of Orchids Using Solid Phase Microextraction and Gas Chromatography Coupled with Mass Spectrometry
Molecules 2014, 19(6), 7913-7936; doi:10.3390/molecules19067913
Received: 25 April 2014 / Revised: 2 June 2014 / Accepted: 6 June 2014 / Published: 11 June 2014
Cited by 4 | PDF Full-text (2226 KB) | HTML Full-text | XML Full-text
Abstract
The volatile fraction of Ophrys sphegodes Mill. subsp. sphegodes, Ophrys bertolonii subsp. benacensis (Reisigl) O. Danesch, E. Danasch & Ehrend. and Neotinea tridentata (Scop.) R.M. Bateman, Pridgeon & M.W. Case, three orchid species with different pollinator attraction strategies, sampled in vivo [...] Read more.
The volatile fraction of Ophrys sphegodes Mill. subsp. sphegodes, Ophrys bertolonii subsp. benacensis (Reisigl) O. Danesch, E. Danasch & Ehrend. and Neotinea tridentata (Scop.) R.M. Bateman, Pridgeon & M.W. Case, three orchid species with different pollinator attraction strategies, sampled in vivo and in situ, were evaluated by headspace solid phase microextraction coupled with gas-chromatography and mass spectrometry. The results were compared with the volatile compounds emitted by flowering plant samples picked from the same populations of orchid species. Hydrocarbons, aldehydes, alcohols and terpenes were the major constituents of “in vivo” orchid scents and some distinctive differences in volatile metabolite composition were observed between Ophrys and Neotinea species. Moreover, the odour bouquets of the picked flowering plant samples were different from the in vivo ones and in particular different proportions of the various terpenes and an increase of α-pinene were observed. In conclusion HS/SPME GCMS proved to be a suitable technique for analyzing and distinguishing the volatile fingerprint of different orchid species, sampled in vivo and in situ in a non-disruptive way, with potentially great advantages for ecophysiological studies of rare and endangered species. Full article
(This article belongs to the Special Issue Microextraction)
Open AccessArticle Determination of Pesticide Residues in Honeybees using Modified QUEChERS Sample Work-Up and Liquid Chromatography-Tandem Mass Spectrometry
Molecules 2014, 19(3), 2911-2924; doi:10.3390/molecules19032911
Received: 3 December 2013 / Revised: 24 February 2014 / Accepted: 26 February 2014 / Published: 6 March 2014
Cited by 5 | PDF Full-text (917 KB) | HTML Full-text | XML Full-text
Abstract
Increasing emissions of chemical compounds to the environment, especially of pesticides, is one of factors that may explain present honeybee colony losses. In this work, an analytical method employing liquid chromatography-tandem mass spectrometry (LC-MS/MS) was optimized for the simultaneous screening of 19 [...] Read more.
Increasing emissions of chemical compounds to the environment, especially of pesticides, is one of factors that may explain present honeybee colony losses. In this work, an analytical method employing liquid chromatography-tandem mass spectrometry (LC-MS/MS) was optimized for the simultaneous screening of 19 pesticides which have not been yet determined in honeybee samples from northern Poland (Pomerania). The sample preparation, based on the QuEChERS method combining salting-out liquid-liquid extraction to acetonitrile and a dispersive-SPE clean-up, was adjusted to honeybee samples by adding a small amount of hexane to eliminate beeswax. The recovery of analytes ranged from 70% to 120% with relative standard deviation ≤20%. The limits of detection were in the range of 0.91–25 ng/g. A total of 19 samples of honeybees from suspected pesticide poisoning incidents were analyzed, in which 19 different pesticides were determined. Full article
(This article belongs to the Special Issue Microextraction)

Review

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Open AccessReview Microextraction Techniques Coupled to Liquid Chromatography with Mass Spectrometry for the Determination of Organic Micropollutants in Environmental Water Samples
Molecules 2014, 19(7), 10320-10349; doi:10.3390/molecules190710320
Received: 13 May 2014 / Revised: 2 July 2014 / Accepted: 10 July 2014 / Published: 16 July 2014
Cited by 9 | PDF Full-text (541 KB) | HTML Full-text | XML Full-text
Abstract
Until recently, sample preparation was carried out using traditional techniques, such as liquid–liquid extraction (LLE), that use large volumes of organic solvents. Solid-phase extraction (SPE) uses much less solvent than LLE, although the volume can still be significant. These preparation methods are [...] Read more.
Until recently, sample preparation was carried out using traditional techniques, such as liquid–liquid extraction (LLE), that use large volumes of organic solvents. Solid-phase extraction (SPE) uses much less solvent than LLE, although the volume can still be significant. These preparation methods are expensive, time-consuming and environmentally unfriendly. Recently, a great effort has been made to develop new analytical methodologies able to perform direct analyses using miniaturised equipment, thereby achieving high enrichment factors, minimising solvent consumption and reducing waste. These microextraction techniques improve the performance during sample preparation, particularly in complex water environmental samples, such as wastewaters, surface and ground waters, tap waters, sea and river waters. Liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS) and time-of-flight mass spectrometric (TOF/MS) techniques can be used when analysing a broad range of organic micropollutants. Before separating and detecting these compounds in environmental samples, the target analytes must be extracted and pre-concentrated to make them detectable. In this work, we review the most recent applications of microextraction preparation techniques in different water environmental matrices to determine organic micropollutants: solid-phase microextraction SPME, in-tube solid-phase microextraction (IT-SPME), stir bar sorptive extraction (SBSE) and liquid-phase microextraction (LPME). Several groups of compounds are considered organic micropollutants because these are being released continuously into the environment. Many of these compounds are considered emerging contaminants. These analytes are generally compounds that are not covered by the existing regulations and are now detected more frequently in different environmental compartments. Pharmaceuticals, surfactants, personal care products and other chemicals are considered micropollutants. These compounds must be monitored because, although they are detected in low concentrations, they might be harmful toward ecosystems. Full article
(This article belongs to the Special Issue Microextraction)
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Open AccessReview Microextraction Techniques Used in the Procedures for Determining Organomercury and Organotin Compounds in Environmental Samples
Molecules 2014, 19(6), 7581-7609; doi:10.3390/molecules19067581
Received: 17 April 2014 / Revised: 20 May 2014 / Accepted: 30 May 2014 / Published: 6 June 2014
Cited by 5 | PDF Full-text (581 KB) | HTML Full-text | XML Full-text
Abstract
Due to human activities, the concentrations of organometallic compounds in all parts of the environment have increased in recent decades. The toxicity and some biochemical properties of mercury and tin present in the environment depend on the concentration and chemical form of [...] Read more.
Due to human activities, the concentrations of organometallic compounds in all parts of the environment have increased in recent decades. The toxicity and some biochemical properties of mercury and tin present in the environment depend on the concentration and chemical form of these two elements. The ever-increasing demand for determining compounds at very low concentration levels in samples with complex matrices requires the elimination of interfering substances, the reduction of the final extract volume, and analyte enrichment in order to employ a detection technique, which is characterised by high sensitivity at low limits of quantification. On the other hand, in accordance with current trends, the analytical procedures should aim at the miniaturisation and simplification of the sample preparation step. In the near future, more importance will be given to the fulfilment of the requirements of Green Chemistry and Green Analytical Chemistry in order to reduce the intensity of anthropogenic activities related to analytical laboratories. In this case, one can consider the use of solvent-free/solvent-less techniques for sample preparation and microextraction techniques, because the use of the latter leads to lowering the quantity of reagents used (including solvents) due to the reduction of the scale of analysis. This paper presents an overview of microextraction techniques (SPME and LPME) used in the procedures for determining different chemical forms of mercury and tin. Full article
(This article belongs to the Special Issue Microextraction)
Open AccessReview Applications of Liquid-Phase Microextraction in the Sample Preparation of Environmental Solid Samples
Molecules 2014, 19(5), 6776-6808; doi:10.3390/molecules19056776
Received: 21 April 2014 / Revised: 19 May 2014 / Accepted: 21 May 2014 / Published: 23 May 2014
Cited by 5 | PDF Full-text (315 KB) | HTML Full-text | XML Full-text
Abstract
Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research [...] Read more.
Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc.) published in the last decade. Several innovative liquid-phase microextraction (LPME) techniques that have emerged recently have also been applied as an aid in sample preparation of these samples: single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME). Besides the common organic solvents, surfactants and ionic liquids are also used. However, these techniques have to be combined with another technique to release the analytes from the solid sample into an aqueous solution. In the present review, the published methods were categorized into three groups: LPME in combination with a conventional solvent extraction; LPME in combination with an environmentally friendly extraction; LPME without previous extraction. The applicability of these approaches to the sample preparation for the determination of pollutants in solid environmental samples is discussed, with emphasis on their strengths, weak points and environmental impact. Full article
(This article belongs to the Special Issue Microextraction)

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