Search results for "Clean-up"

Comparison of Two Solid-Phase Extraction (SPE) Methods for the Identification and Quantification of Porcine Retinal Protein Markers by LC-MS/MS

2018

Proper sample preparation protocols represent a critical step for liquid chromatography-mass spectrometry (LC-MS)-based proteomic study designs and influence the speed, performance and automation of high-throughput data acquisition. The main objective of this study was to compare two commercial solid-phase extraction (SPE)-based sample preparation protocols (comprising SOLA&micro

Determination of amphetamines in hair by integrating sample disruption, clean-up and solid phase derivatization

2016

The utility of matrix solid phase dispersion (MSPD) for the direct analysis of amphetamines in hair samples has been evaluated, using liquid chromatography (LC) with fluorescence detection and precolumn derivatization. The proposed approach is based on the employment of MSPD for matrix disruption and clean-up, followed by the derivatization of the analytes onto the dispersant-sample blend. The fluorogenic reagent 9-fluorenylmethyl chloroformate (FMOC) has been used for derivatization. Different conditions for MSPD, analyte purification and solid phase derivatization have been tested, using amphetamine (AMP), methamphetamine (MET), ephedrine (EPE) and 3,4-methylenedioxymethamphetamine (MDMA)…

Solid-Phase Extraction and Clean-Up Procedures in Pharmaceutical Analysis

2012

Solid-phase extraction (SPE) using small cartridges filled with sorbents of a small particle size has rapidly established itself as an important sample clean-up technique. It has prospered at the expense of liquid-liquid extraction (LLE), which is considered labor intensive and frequently plagued by problems, such as emulsion formation and use of large volumes of hazardous solvents. A remarkable characteristic of SPE is its easy adaptation to on-line mode by column-switching techniques; switching can be effected manually or by automated controllers. The same analyte/sorbent interactions that are exploited in liquid chromatography (LC) are of use in SPE, but particle sizes employed are great…

Pressurized liquid extraction of organic contaminants in environmental and food samples

2015

Pressurized liquid extraction (PLE) is an automated technique that uses elevated temperature and pressure to achieve exhaustive extraction from solid matrices, so reducing solvent consumption and enhancing sample throughput when compared with traditional procedures. Hence, it can be considered an environment-friendly technique, generating small volumes of waste and reducing costs and time. This review focuses on application of this green technique to the analysis of organic contaminants in food and environmental matrices for monitoring purposes. We examine fundamentals and key aspects of the development of a PLE method, including pressurized hot-water extraction, together with some relevant…

A LC/MS/MS method for the simultaneous quantification of free and masked fumonisins in maize and maize-based products

2008

An LC-ESI-MS/MS method for the simultaneous detection of the main fumonisins and their hydrolysed derivatives is described, allowing for a simplified sample preparation without previous clean up. The method has a very low quantification limit (10 µg/kg for FB1, 12 µg/kg for FB2 and FB3, 70 µg/kg for HFB1, HFB2 and HFB3 in maize flour) and a very good recovery for all the analytes. The method has been applied to check several maize-based foods for the presence of free and bound forms of fumonisins, the latter being determined after alkaline hydrolysis as hydrolysed derivatives. Bound fumonisins were found to be present not only in thermally treated maize-based products but also in mild proc…

Simultaneous clean up of fish fat containing low levels of residues and separation of PCB from chlorinated pesticides by thin-layer chromatography

1974

Levels, fingerprint and daily intake of polycyclic aromatic hydrocarbons (PAHs) in bread baked using wood as fuel

2009

Concentrations, fingerprint and daily intake of 16 PAHs in 15 bread samples baked using wood as fuel are examined in this work. Analysis was performed by GC/MS after saponification of the samples and clean up of the extract. The total concentration of the 16 analytes varies from 6 to 230 microg/kg on dry weight (d.w.). The better extraction procedure was estimated by analyzing test-samples and using different extraction methods. Additionally, for every analyzed sample, the extraction yield has been determined by the use of surrogate standards. Extraction yields were never less than 77% and in most cases almost 100%. The profiles of PAHs (percentage) are similar for all the analyzed samples …

Photochemical sample treatment: a greener approach to chlorobenzene determination in sediments.

2014

Abstract Due to worker׳s exposure, solvent and stationary phases׳ consumption, sample purification is one of the most polluting steps in analytical procedures for determination of organic pollutants in real samples. The use of photochemical sample treatment represents a valid alternative methodology for extracts clean up allowing for a reduction of the used amount of organic solvents. In this paper we report the first application on the photolytic destruction of organic substances to eliminate some of the interferences in the analysis of Chlorobenzenes in sediment samples. The method׳s efficiency and robustness were compared with classic silica column purification process currently used in …

Determination of microcystins in fish by solvent extraction and liquid chromatography

2005

A liquid chromatography electrospray mass spectrometry (LC/ESI/MS) method has been developed to identify and quantify microcystins in fish liver and intestine. Microcystins (MCs) were extracted from 500 mg sample with methanol-water (85:25, v/v) and the extracts concentrated to 250 microl. The parameters were optimized by a full factorial 2(3) design. Neither laborious pre-treatment nor clean up were necessary. MCs were separated using conventional C18 column and an acetonitrile-acidified water (pH 3) gradient. Negative samples (without MCs) were discriminated by liquid chromatography diode array detection (LC/DAD). The limits of detection (LOD) and the limits of quantification (LOQ) result…

Using semi-permeable membrane devices as passive samplers

2007

Abstract We discuss the present state of, and future developments in, using semi-permeable membrane devices (SPMDs) for environmental monitoring of organic pollutants. SPMDs allow the determination of time-weighted average concentrations of bioavailable pollutants in the sampled media, reducing significantly the costs of analysis compared with active samplers. We summarize developments in SPMDs, including simplified devices and devices modified by incorporating solvents other than triolein, and applications. We review contaminants (e.g., organotin compounds, polycyclic musk, triclosan, petroleum biomarkers, nitrated PAHs, polychlorinated naphthalenes and a wide range of pesticides sampled i…