Search results for "Microextraction"

Recent Advances in Sample Preparation for Pesticide Analysis

2012

Much progress has been made in pesticide analysis in the past decade. During this time, hyphenated techniques involving highly efficient separation with sensitive mass spectrometric detection have become the methods of choice. Even with such powerful instrumental techniques, a demanding task in pesticide residue analysis is the development of multiresidue methods for the determination of pesticides in air, water, soil, sediment, biota, and food. This chapter summarizes the analytical characteristics of the different methods of sample preparation for the determination of pesticide residues in a variety of food matrices, and surveys their recent applications in combination with gas chromatogr…

Comparison of solid-phase microextraction and stir bar sorptive extraction for determining six organophosphorus insecticides in honey by liquid chrom…

2004

Abstract Two approaches based on sorptive extraction, solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE), in combination with liquid chromatography (LC)–atmospheric pressure chemical ionization mass spectrometry (MS) have been assayed for analyzing chlorpyriphos methyl, diazinon, fonofos, phenthoate, phosalone, and pirimiphos ethyl in honey. In both, SPME and SBSE, enrichment was performed using a poly(dimethylsiloxane) coating. Significant parameters affecting sorption process such as sample volume, sorption and desorption times, ionic strength, elution solvent, and dilution (water/honey) proportion were optimized and discussed. Performance of both methods has been …

Current trends in affinity-based monoliths in microextraction approaches: A review

2019

Abstract This article reviews the research contributions along the past five years concerning to monolithic materials for the development of affinity-based sorbents in the field of microextraction techniques. The first part of this paper includes an introduction regarding monolithic affinity media and information of different binding agents (such as immunoglobulin-binding proteins, enzymes, lectins, antibodies, aptamers, dyes and immobilized metal ions and nanoparticles, among others) that can act as affinity ligands. Then, the preparation of monoliths and ligand immobilization strategies as well as the different available formats (syringes, pipette tips, spin columns, capillaries, disks an…

An in-tube SPME device for the selective determination of chlorophyll a in aquatic systems.

2010

We report a new device for the estimation of the content of chlorophyll a pigment in water samples as an indicator of water quality. The extraction of the pigment from water was also optimized. 10 mL of water was filtered through a nylon filter (45m pore size and 13 mm of diameter), after the chlorophylls were dissolved by immersing the filter in 1 mL of a low non-hazardous solvent as ethanol. An in-valve in-tube SPME device coupled to capillary liquid chromatography with diode array detection was designed. A capillary column of 70 cm in length (0.32 mm i.d. coated with 5% diphenyl–95% polydimethylsiloxane, 3m coating thickness) was used as the loop of the injection valve for preconcentrati…

Comparison of different methods: static and dynamic headspace and solid-phase microextraction for the measurement of interactions between milk protei…

2002

Interactions between 10 aroma compounds from different chemical classes and 5 mixtures of milk proteins have been studied using static or dynamic headspace gas chromatography and solid-phase microextraction (SPME). Static headspace analysis allows the quantification of the release of only the most abundant compounds. Dynamic headspace analysis does not allow the discrimination of flavor release from the different protein mixtures, probably due to a displacement of headspace equilibrium. By SPME analysis and quantification by GC-MS (SIM mode) all of the volatiles were quantified. This method was optimized to better discriminate aroma release from the different milk protein mixtures and then …

Solid Phase Microextraction (SPME) of Orange Juice Flavor:  Odor Representativeness by Direct Gas Chromatography Olfactometry (D-GC-O)

2003

The sensorial quality of solid phase microextraction (SPME) flavor extracts from orange juice was measured by direct gas chromatogrphy-olfactometry (D-GC-O), a novel instrumental tool for evaluating odors from headspace extracts. In general, odor impressions emerging from SPME extracts poorly resembled that of the original orange juice. In an attempt to improve the sensorial quality of extracts, sample equilibration and exposure times were varied on Carboxen/polydimethylsiloxane (CAR/PDMS) and divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fibers. Best sensorial results were obtained with the DVB/CAR/PDMS fiber exposed for the shortest time; a trained panel of eight assess…

Determination of antifreeze substances in the airport runoff waters by solid-phase microextraction and gas chromatography–mass spectrometry method

2016

Abstract A new method has been developed for the determination of antifreeze agents such as ethylene glycol (EG), propylene glycol (PG), and diethylene glycol (DEG) in the samples of airport runoff water. The method is based on headspace solid–phase microextraction (HS–SPME) of target analytes, which is coupled with gas chromatography–mass spectrometry (GC–MS). Until now, there was a lack of appropriate methodology for collecting reliable data about the concentration levels of these toxic de/anti-icing substances in the new type of environmental samples such as the airport runoff water. The evaluation of green extraction technique, i.e., HS–SPME resulted in establishing the optimal extracti…

Miniaturized liquid chromatography coupled on-line to in-tube solid-phase microextraction for characterization of metallic nanoparticles using plasmo…

2018

Abstract This tutorial aims at providing guidelines for analyzing metallic nanoparticles (NPs) and their dispersions by using methods based on miniaturized liquid chromatography with diode array detection (MinLC-DAD) and coupled on-line to in-tube solid-phase microextraction (IT-SPME). Some practical advice and considerations are given for obtaining reliable results. In addition, this work outlines the potential applications that set these methodologies apart from microscopy-related techniques, dynamic light scattering, single particle ICP-MS, capillary electrophoresis, field-flow fractionation and other chromatographic configurations, which are discussed and mainly seek to accomplish size …

Determination by solid-phase microextraction/gas chromatography/mass spectrometry of polycyclic aromatic hydrocarbons in bitumen fumes during road pa…

1999

Free fatty acids and other volatile compounds for the characterisation of “Vastedda della valle del Belìce” cheese Acidos grasos libres y otros const…

2010

The analysis of the volatile constituents of “Vastedda della valle del Belice”, a typical Sicilian pasta filata cheese, was performed using solid phase microextraction and high-resolution gas chromatography/mass spectrometry. The research aimed to verify if the volatile fraction, determinant for cheese flavor, differs among producers and/or production seasons. The samples were provided by four producers from the area of the Protected Designation of Origin (PDO) production, during two different seasons of production. A total of 42 volatile components were identified: the main components were found to be butanoic, hexanoic, octanoic, and decanoic acid. Free fatty acids were quantified using t…