1,052 research outputs found
Metal–Organic Frameworks in Solid-Phase Extraction Procedures for Environmental and Food Analyses
No full textHigh-Performance Liquid Chromatography/Mass Spectrometry Methods in Pesticide Analysis
No full textIn this article, a detailed overview of the current high-performance liquid chromatography/mass spectrometry (HPLC/MS) instrumentation, suitable for the determination of a large number of pesticides, is reported. Particular emphasis is given to the role of the mass spectrometric apparatus involved in each interfacing technique with several information regarding the ionization processes, analyzer principles, and system configurations. The article is an up-to-date picture of the current instrumentation available and the reader will find only brief references to some important historical approaches that are no longer in use
Profiling of non-esterified fatty acids in human plasma using liquid chromatography-electron ionization mass spectrometry
No full textThis paper focuses on the development of a
novel approach to analyze underivatized fatty acids in
human plasma. The method is based on liquid–liquid
extraction followed by reversed phase liquid chromatography
coupled to direct-electron ionization mass spectrometry
(LC-Direct-EI-MS). The assay is validated. Calibrations
show satisfactory linearity and precision in the investigated
range of linearity. Recoveries span from 75% to 104%. The
method limits of detection, varying from 0.53 to 5.35 μM,
are satisfactory for the quantitation of non-esterified fatty
acids (NEFAs) in plasma at physiological levels. The
method has been successfully applied to the NEFAs
profiling of plasma samples from healthy adult volunteers
and subjects affected by diabetes mellitus. Compared with
published protocols based on gas chromatography–mass
spectrometry and liquid chromatography coupled to electrospray
ionization mass spectrometry, this method does not
require derivatization and does not show matrix effects,
thus simplifying sample preparation procedure and reducing
the total time of analysis to approximately 90 min. In
addition, Direct-EI-MS allows the acquisition of highquality
NIST library-matchable EI spectra, allowing an
easy-to-obtain identification of the target NEFAs
Occurrence of specific environmental risk factors in brain tissues of sudden infant death and sudden intrauterine unexpected death victims assessed with gas chromatography–tandem mass spectrometry
No full textAtmospheric Pressure Vaporization Mechanism for Coupling a Liquid Phase with Electron Ionization Mass Spectrometry
No full textA novel liquid chromatography-mass spectrometry (LC-MS) interfacing concept is presented and discussed. The new interface, called Liquid-EI (LEI), is based on electron ionization (EI) but, differently from any previous attempt, the vaporization of solutes and mobile phase takes place at atmospheric pressure into a specifically designed region, called “vaporization micro-channel”, before entering the high-vacuum ion source. The interface is completely independent from the rest of the instrumentation, and can be adapted to any gas chromatography-mass spectrometry (GC-MS) system, as an add-on for a rapid LC-MS conversion. Pressure drop and temperature gradient between LC and MS were considered to enhance the analyte response and reduce band broadening and/or solute carryovers. A fused silica liner, placed inside the vaporization micro-channel, acts as an inert vaporization surface speeding up the gas-phase conversion of large molecules while lessening possible memory effects. The liner is easily replaceable for a quick and extremely simple interface maintenance. Proof of concept and detailed description of the interface are here presented
Derivatization Strategies in Flavor Analysis: An Overview over the Wine and Beer Scenario
No full textWine and beer are the most appreciated and consumed beverages in the world. This success is mainly due to their characteristic taste, smell, and aroma, which can delight consumer’s palates. These olfactory characteristics are produced from specific classes of volatile compounds called “volatile odor-active compounds” linked to different factors such as age and production. Given the vast market of drinking beverages, the characterization of these odor compounds is increasingly important. However, the chemical complexity of these beverages has led the scientific community to develop several analytical techniques for extracting and quantifying these molecules. Even though the recent “green-oriented” trend is directed towards direct preparation-free procedures, for some class of analytes a conventional step like derivatization is unavoidable. This review is a snapshot of the most used derivatization strategies developed in the last 15 years for VOAs’ determination in wine and beer, the most consumed fermented beverages worldwide and among the most complex ones. A comprehensive overview is provided for every method, whereas pros and cons are critically analyzed and discussed. Emphasis was given to miniaturized methods which are more consistent with the principles of “green analytical chemistry”
The Rapid Measurement of Benzodiazepines in a Milk-Based Alcoholic Beverage Using QuEChERS Extraction and GC–MS Analysis
No full textBenzodiazepines (BDZs) are widely used as tranquilizers and antidepressive
drugs in common clinical practice. However, their ready
availability and their synergistic effects with alcohol make them
attractive for criminal intentions. To prove criminal action for legal
reasons, it is often necessary to analyze beverage residues from a
crime scene. Milk-based alcoholic drinks (whiskey creams) are gaining
popularity due to their lower alcohol content pleasant taste.
However, the complexity of this sample, containing proteins and
fatty acids, can mask the presence of drugs or other substances in
standard analysis methods. These characteristics make whiskey
creams highly suitable for illicit purposes. In this study, eight BDZs,
including diazepam, chlordiazepoxide, clobazam, flunitrazepam, bromazepam,
flurazepam, nitrazepam and clonazepam, were extracted
from whiskey cream using the Quick, Easy, Cheap, Effective,
Rugged and Safe (QuEChERS) method and analyzed using GC–MS.
The QuEChERS protocol can efficiently separate most of the matrix
from the target compounds while maintaining acceptable recoveries.
The presented method is simple and rapid and has been validated in
terms of precision, accuracy and recoveries. Limits of detection and
limits of quantitationwere in the range of 0.02–0.1 and 0.1–0.5 mg/mL,
respectively. Whiskey cream beverages, fortified with commercial
drugs at 20 mg/mL, were extracted and analyzed demonstrating the
applicability of the method in forensic analysis
Liquid chromatography-electron ionization tandem mass spectrometry with the Direct-EI interface in the fast determination of diazepam and flunitrazepam in alcoholic beverages
No full textThis is the first application based on electron ionization (EI) using a Direct-EI LC interface and MS/MS to detect unequivocally target compounds in a very small real sample. The determination and quantification of benzodiazepines (BDZ) in very small residues of beverages, collected at the scene of drug-facilitated crimes (DFC) are mandatory in legal procedures. A specific and sensitive analytical instrumentation is needed, involving little or no sample preparation. Here, a direct flow injection analysis (FIA) of alcoholic beverages spiked with commercially available drugs containing diazepam and flunitrazepam is presented. The method proposed is very fast and requires neither sample preparation nor chromatographic separation. Linearity (R(2) ) was between 0.9977 and 0.9992; LOD and LOQ spanned from 0.01 to 0.02 ng/μL and from 0.1 to 0.5 ng/μL, respectively; intra- and inter-day repeatabilities were between 1 and 8%. No matrix effects (ME) were observed from the comparison of the linear regression curves obtained in real fortified samples and in pure ethanol. Vodka, whisky and white wine specimens were fortified with commercial drugs, Valium(®) and Rohypnol(®) , at two different concentrations (20 and 50 ng/μL) to simulate the typical amounts found in adulterated real samples and analyzed to demonstrate the method applicability to forensic analyses. This article is protected by copyright. All rights reserved
LC-EI-MS: UN NUOVO APPROCCIO STRUMENTALE
No full textIn questo lavoro viene presentato un nuovo strumento, chiamato Liquid-EI (LEI), capace di interfacciare efficacemente la cromatografia liquida (LC) con la spettrometria di massa a ionizzazione elettronica (MS). L’interfaccia LEI è completamente indipendente e può essere adattata ad ogni sistema GC-MS per una rapida conversione ad LC-MS. Il suo funzionamento verrà di seguito descritto
Boosting the Detection Potential of Liquid Chromatography-Electron Ionization Mass Spectrometry Using a Ceramic Coated Ion Source
No full textDetection of target and non-target substances and their characterization in complex samples is a challenging task. Here we demonstrate that coating the electron ionization (EI) ion source of an LC-MS system with a sol-gel ceramic film can drastically improve the detection of high-molecular weight and high-boiling analytes. A new ion source coated with a ceramic material was developed and tested with a mixture of polycyclic aromatic hydrocarbons (PAH) with an increasing number of rings. Comparison of the results obtained with those for an uncoated stainless steel (SS) ion source shows a dramatic improvement in the MS signals, with a nearly 40-fold increase of the signal-to-noise ratio. We also demonstrate the ability of the new system to produce excellent chromatographic profiles for hard-to-detect hormones
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