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MS techniques for analyzing phenols, their metabolites and transformation products of environmental interest
No full textThis overview covers, in particular, chlorinated phenols, alkylphenols and steroidal estrogens that have caused great concern because of their adverse effects, diffusion and resistance to (bio)degradation. We first describe strategies for combining liquid chromatography with mass spectrometry (LC-MS) to recognize metabolites, providing evidence for the advantages and the limitations of the available techniques and predicting future trends in this field. We then review the present state of the art in the analysis of the above compounds. We pay particular attention to those LC-MS methods involving the analysis of target phenolic compounds and identification of their unknown products in the various environmental compartments. (C) 2008 Elsevier Ltd. All rights reserved
LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY FOR PERFORMING CONFIRMATORY ANALYSIS OF VETERINARY DRUGS IN ANIMAL-FOOD PRODUCTS
No full textThis review focuses on recent developments and trends in liquid chromatography coupled to mass spectrometry, with a particular emphasis on tandem mass spectrometry and the new criteria established by the European Union for performing confirmatory analysis of veterinary drugs in animal-food products. The combination of liquid chromatography and tandem mass spectrometry allows unequivocal identification of traces of antibiotics and antibacterial agents in complex biological matrices, such as honey, eggs, milk and meat. The sensitivity of the coupling is particularly useful for confirming the presence of banned substances that require limits of detection as low as possible. (c) 2005 Elsevier Ltd. All rights reserved
Solid-phase extraction followed by high-performance liquid chromatography-ionspray interface-mass spectrometry for monitoring of herbicides in environmental water
No full textIn this work we developed a sensitive and specific multiresidue method, based on reversed-phase liquid chromatography-mass spectrometry, with an ionspray interface (LC-ISI-MS), for determining 53 of most representative compounds of herbicides in water samples. The procedure used involved passing 0.5 l of surface water, 2 l of ground water and 4 l of drinking water samples, respectively, through a 0.5 g graphitized carbon black (GCB) extraction cartridge. Base-neutral and acid herbicides were differential eluted from GCB cartridge and follow analyzed by HPLC-ISI-MS apparatus. A conventional 4.6-mm-ID reversed-phase LC C-18 column, operating with a mobile phase flow-rate of 1 ml/min, was used to chromatograph the analytes. A flow of 100 mu l/min of the column effluent was diverted to the ISI source. The study demonstrates the sensitivity of the technique, with detection limit under 10 ng/l in drinking water samples. Performance data for the method such as recovery and precision are also reported. (C) 2000 Elsevier Science B.V. All rights reserved
Pressurized liquid extraction of chlormequat and mepiquat from cereal flours followed by LC tandem MS analysis
No full textA new analytical method for the rapid extraction and unequivocal confirmation of herbicides chlormequat (CQ) and mepiquat (MQ) in wheat flours and various flours utilized in infant foods was developed.
The extraction procedure is based on pressurized liquid extraction (PLE), using ethanol as extractant at high pressure and temperatures; the extraction rapidity is combined with the elevated selectivity and sensibility of the LC-MS-MS.
Analytes were separated by ion exchange chromatography and d9-chlormequat was used as internal standard.
Mass-spectrometric detection was conducted with a triple quadrupole equipped with a TurboIonSpray source operating in positive ionization mode.
Two Selected Reaction Monitoring (SRM) were chosen for each analyte and the developed analytical method was validated by evaluating recovery, precision, linear dynamic range, sensitivity, limit of detection (LOD) and limit of quantitation (LOQ).
Special emphasis was placed on the versatility and robustness of automated PLE for routine trace determination of the selected analytes; moreover, the use of ethanol allowed one to inject the sample directly, avoiding the evaporation step.
In particular, the study addresses the impact of the food matrix on ion suppression by comparing solvent calibration curves with those obtained by blank extracts, spiked with analytes. Calibration curves in matrix displayed a slope lower of about 20% than that noticed in the solvent.
Recoveries ranged from 83 to 99% at a fortification level of 10 ppb, corresponding to the maximum residue limit established by the European Union, while intra-day precision was less than 10% for all samples.
The developed method was applied to detect the incidental presence of MQ and CQ in different cereal flours.
In particular, traces of the selected herbicides were detected in about 50% of baby foods
OPTIMIZATION OF HIGH PERFORMANCE LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY APPARATUS FOR DETERMINATION OF IMIDAZOLINONE HERBICIDES IN SOIL AT LEVELS OF A FEW PPB
No full textA rapid, simple and accurate method for the simultaneous determination of residues of the imidazolinone herbicides (imazapyr, imazaquin, imazamethabenz and imazamethabenz-methyl) in soil is described, The basis of the method is the formation of a supernatant by sonication of the soil with 0.1 M KCI, After removal from the soil particles, the pesticides are quantified by reversed-phase liquid chromatography/mass spectrometry with an Turboionspray interface (LC/TurboIS-MS). This is a new high flow ionspray (IS) interface developed by Sciex, A conventional 4.6 mm i.d. reversed phase LC C-18 column operating with a mobile phase flow rate of 1 mL/min, was used to chromatograph the analytes, A flow of 200 mu L/min. of the column effluent was diverted to the ISI source. The effects of acid concentration on IS-MS detector response in the mobile phase were investigated. The effects on the production of diagnostic fragments produced by varying the orifice plate voltage and the response of the MS detector were also evaluated. For the analyte considered, the response of the mass detector was linearly related to the amount of analyte injected between 1 and 50 ng, Recoveries from a variety of soil types, fortified over the range 50-200 ppb, are essentially quantitative for each imidazolinone and the detection limits (signal-to-noise ratio = 3) of the method are always lower than 14 ng/g, (C) 1998 John Wiley & Sons, Ltd
Simultaneous determination of base/neutral and acid herbicides in natural water at the part per trillion level
No full textA new method for the simultaneous identification and quantification of base/neutral and acidic pesticides at a low nanogram per liter concentration level in natural waters is presented. The method includes enrichment of the compounds by solid phase extraction on graphitized carbon black, followed by sequential elution of the base/neutral and acidic pesticides. Identification and quantification of the compounds is performed with HPLC-ESI-MS. This procedure involves passing 1 L of ground water and 2 L of drinking water samples through a 0.5 g graphitized carbon black (GCB) extraction cartridge. A conventional 4.6-mm-i.d. reversed phase LC C-18 operating with a 1 mt min-l flow of the mobile phase was used to chromatograph the analytes. A flow of 100 mu L min(-1) of the column effluent was diverted to the ESI source. The ESI source was operated in positive ion mode for base/neutral pesticides and in negative-ion mode for acid pesticides. For the analyte considered, the response of the mass detector was linearly related to the amount of the analytes injected between 5 and 250 ng. In all cases, recoveries of the analytes were better than 90%. The limit of detection (signal-to-noise ratio = 3) of the method for the pesticides considered in drinking water samples was estimated to be about 3-10 ng L-1
LIQUID CHROMATOGRAPHIC/MASS SPECTROMETRIC DETERMINATION OF DESMEDIPHAN AND PHENMEDIPHAN AND THEIR METABOLITES IN SOIL
No full textA simple method is described for the simultaneous determination of residues of 2 carbamate herbicides (phenmedipham and desmedipham) and related metabolites (m-aminophenol, aniline, and m-toluidine) in soil. The analytes are extracted from spiked soils with methanol. The solvent/soil suspension is centrifuged, and the supernatant is directly injected, without any further cleanup, into a reversed-phase liquid chromatography/mass spectrometry apparatus equipped with a TurbolonSpray interface. The method was tested on 5 soils having different physicochemical properties. Recoveries from the soil types, spiked over the range of 50-200 ppb, were essentially quantitative for each analyte. The detection limits of the method are less than or equal to 25 ng/g
Development of a method based on pressurized fluid extraction and liquid chromatography tandem mass spectrometry for determination of arylphenoxypropionic herbicides in soil
No full textQUADRUPOLE TIME-OF-FLIGHT VERSUS TRIPLE-QUADRUPOLE MASS SPECTROMETRY FOR THE DETERMINATION OF NON STEROIDAL ANTIINFLAMMATORY DRUGS IN SURFACE WATER BY LIQUID CHROMATOGRAPHY/TANDEM MASS SPECTROMETRY
No full textA triple-quadrupole instrument and a hybrid quadrupole/time-of-flight (TOF) mass spectrometer were compared for the determination of pharmaceutical compounds in water samples. The drugs investigated were the analgesics Ibuprofen, Fenoprofen, Ketoprofen, Naproxen, and Diclofenac. The recently introduced Q2-pulsing function, which enhances the transmission of fragment ions of a selected m/z window from the collision cell into the TOF analyzer, improved the sensitivity of product ion scans on the quadrupole/TOF instrument. The selectivity is much better on quadrupole/TOF systems than on triple quadrupoles because the high resolving power of the reflectron-TOF mass analyzer permits high-accuracy fragment ion selection. This minimizes interferences from environmental matrices and allows acquisition of full spectra for selected analytes with better signal-to-noise characteristics than comparable spectra obtained with a scanned quadrupole. The qualitative information obtained (mass accuracy, resolution and full-scan spectra) by hybrid quadrupole/TOF mass spectrometry allows a more certain identification of analytes in environmental matrices at trace levels. Sample enrichment of water samples was achieved by a solid-phase extraction procedure. Average recoveries for loading 1 L of samples varied from 88 to 110%, and the quantification limits were less than 1.2 ng/L for the triple-quadrupole instrument (in MRM mode) and less than 3 ng/L for the quadrupole/TOF instrument. Copyright (C) 2003 John Wiley Sons, Ltd
PRESSURIZED-LIQUID EXTRACTION FOR DETERMINATION OF IMIDAZOLINONE HERBICIDES IN SOIL
No full textA rapid and simple method has been developed for determination of imidazolinone (IMI) residues in soil. Extraction of the analytes from the soil matrix was performed with a pressurized-liquid-extraction apparatus built in this laboratory. Four different types of soil sample (clay, clay loam, sandy clay loam, and silty loam) were fortified with target compounds at levels of 10 and 50 ng g-1 by a procedure which can mimic weathered soils. The samples were then dried and packed in a 25 cm × 4.6 mm i. d. stainless steel column; this was placed inside a GC oven and extracted by passing an aqueous solution of KCl (0.1 M, 20 mL) through the column at 90°C. Quantification of the analytes in the final extract (50-μL injection) was performed by reversed-phase liquid chromatography-mass spectrometry with a TurbolonSpray interface. Recoveries of the analytes were greater than 83% and RSD less than 7%. The method detection limit was in the 1 - 2.5 ng g-1 range in analysis by time-scheduled selected-ion monitoring (SIM)
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