Search results for "solid phase"
showing 10 items of 360 documents
Assessment of two extraction methods to determine pesticides in soils, sediments and sludges. Application to the Túria River Basin.
2014
Pressurized liquid extraction (PLE) and Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) extraction methods were optimized for the simultaneous determination of 50 pesticides in sediment, soils and sewage sludge. For QuEChERS development, several buffers and dispersive solid-phase extraction clean-up (dSPE) sorbents were tested. In the PLE method, several parameters affecting the extraction efficiency, such as organic solvent, amount of sample, cell size, temperature, pressure, static time, number of cycles and % of flush, as well as sorbent used for the on-line clean up, were also evaluated. PLE and QuEChERS were assessed and compared in obtained recoveries (33-89% versus 25-120%)…
Determination of pharmaceuticals in soils and sediments by pressurized liquid extraction and liquid chromatography tandem mass spectrometry
2010
13 páginas, 4 figuras, 6 tablas.
Risk assessment on the presence of pharmaceuticals in sediments, soils and waters of the Pego-Oliva Marshlands (Valencia, eastern Spain).
2012
9 páginas, 3 figuras, 2 tablas.
Expanding the application of stir bar sorptive-dispersive microextraction approach to solid matrices: Determination of ultraviolet filters in coastal…
2018
This work describes a new method for the determination of organic compounds in solid samples based on the equilibrium desorption of the analytes in an aqueous phase followed by stir bar sorptive-dispersive microextraction (SBSDME). Sand samples, contaminated with UV filters due to bathing and recreational activities, were dispersed in an aqueous medium by using a coated stir bar with CoFe2O4@oleic acid magnetic nanoparticles. The UV filters were physically desorbed from the surface of the sand particles and rapidly adsorbed on the hydrophobic coating of the nanoparticles, which were retrieved by means of their magnetism after stopping the stirring. In this manner, both preconcentration of t…
In syringe hybrid monoliths modified with gold nanoparticles for selective extraction of glutathione in biological fluids prior to its determination …
2020
Abstract In this work, a simple device for extraction glutathione (GSH) in biological fluids using a hybrid monolithic material within a polypropylene syringe is developed. For this purpose, glycidyl methacrylate-based monolith was firstly prepared within this housing material, and the polymer was modified with different ligands (ammonia, cysteamine and cystamine). The resulting materials (containing amine or thiol groups, respectively) were then functionalized with gold nanoparticles (AuNPs). The hybrid material that gave the largest AuNPs coverage was selected as solid-phase (SPE) sorbent and several variables affecting the extraction recovery of this compound were investigated. Under opt…
Extraction of β-blockers from urine with a polymeric monolith modified with 1-allyl-3-methylimidazolium chloride in spin column format
2020
Abstract A glycidyl methacrylate-based monolith was modified with imidazolium-based ionic liquid (IL) to be used as stationary phase for solid-phase extraction (SPE). The host monolithic support was prepared by in-situ UV polymerization in spin column format. Two approaches were developed to incorporate the IL into the polymeric monolithic matrix: generation of IL onto the surface monolith, and copolymerization by addition of the IL to the polymerization mixture, which gave the best results. The resulting sorbent materials were morphologically characterized and used for the isolation of five β-blockers from human urine samples. All SPE steps were accomplished by centrifugation, which reduce…
Assays for Detection of Fungal Hallucinogens Such as Psilocybin and Psilocin
2016
Abstract Methods applicable to the detection of hallucinogenic indole compounds, namely psilocybin, psilocin, and related molecules, that have been developed so far for purposes of mycological research, toxicological studies, or forensic investigations are described in this chapter. The most current literature as well as some interesting older publications are cited, providing a historical overview of the subject. Methods of qualitative and quantitative analysis are presented. Additionally, preliminary purification steps and sample treatment before the exact quantitative determination are proposed. The methods described utilized various analytical techniques for the measurement of psilocybi…
Sensitive Screening of New Psychoactive Substances in Serum Using Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry.
2021
Abstract Analysis of new psychoactive substances (NPS) still poses a challenge for many institutions due to the number of available substances and the constantly changing drug market. Both new and well-known substances keep appearing and disappearing on the market, making it hard to adapt analytical methods in a timely manner. In this study we developed a qualitative screening approach for serum samples by means of liquid chromatography--quadrupole time-of-flight mass spectrometry. Samples were measured in data-dependent auto tandem mass spectrometry mode and identified by fragment spectra comparison, retention time and accurate mass. Approximately 500 NPS, including 195 synthetic cannabino…
Occurrence of glyphosate in beer from the Latvian market.
2018
A sensitive LC-MS/MS method for the determination of glyphosate in beer has been developed, validated, and applied to analyse 100 beer samples from 24 different producers and distributors in Latvia. The selected samples represented most beer brands and varieties sold in local supermarkets. Different procedures for sample preparation and chromatographic separation were compared. The final version of the method consisted of solid phase extraction, chromatographic separation on aminopropyl stationary phase, and detection using tandem mass spectrometry. The concentration of glyphosate in beer varied from below the LOD of 0.2 μg kg-1 up to 150 μg kg-1, higher than previously reported. Significan…
Analysis of cannabinoids by liquid chromatography–mass spectrometry in milk, liver and hemp seed to ensure food safety
2017
A method for determining cannabinoids, Δ9-tetrahidrocannabinol (THC), 11-nor-9-carboxy-Δ9-THC (THC-COOH) and 11-hidroxy-Δ9-THC (THC-OH) in milk, liver and hemp seeds based on liquid chromatography tandem mass spectrometry has been optimized and validated. Analytes were extracted with methanol and the extracts cleaned-up by solid-phase extraction using Oasis HLB (60 mg). The developed method was validated according to the Commission Decision 2002/657/EC. The decision limit (CCα) and detection capability (CCβ) ranged from 3.10–10.5 ng g−1 and 3.52–11.5 ng g−1, the recoveries were 76–118% and matrix effect ranged from −17.8% to 19.9% in the three matrices studied. The method was applied to foo…