1,720,972 research outputs found
Analisi di contaminanti emergenti: messa a punto di un metodo multiresiduo GC-MS per l'analisi di PCPs (Personal Care Products) nelle acque
No full textI componenti chimici presenti nei prodotti per la cura e l’igiene personale (PCPs), riconosciuti come contaminanti emergenti e persistenti nell’ambiente, includono un’ampia e diversificata gamma di sostanze chimiche: tensioattivi, profumi, filtri UV, antibatterici, conservanti , . Un singolo metodo di analisi per differenti classi di composti risulta molto vantaggioso per il loro monitoraggio, in quanto riduce i tempi di analisi, il numero di campioni da prelevare e i costi.
Si è messo a punto un metodo multiresiduo che utilizza Gas Cromatografia-Spettrometria di Massa (GC-MS) per l'analisi simultanea di PCPs volatili appartenenti a classi diverse e presenti in tracce in matrici acquose ambientali.
Il campione è purificato e preconcentrato usando estrazione in fase solida (SPE) prima dell’analisi GC-MS. Dopo un preliminare studio bibliografico , sono stati valutati due tipi di cartucce SPE: C-18 (Restek) e STRATA-X (Phenomenex), con caratteristiche sia lipofile che idrofile. Sono stati esaminati e confrontati diversi eluenti, volumi di eluente e altre condizioni per la preconcentrazione del campione. Il metodo è stato testato su 30 composti target rappresentativi delle diverse classi di PCPs. Si è osservato che le rese di estrazione risultano più elevate utilizzando cartucce STRATA-X, eluendo con Etilacetato, con rese medie > 70%
Development of advanced analytical methods for the determination of emerging pollutants in environmental waters
No full textThis thesis work was focused on the analytical determination of emerging
pollutants in environmental water matrix, concerning preparative step and
analysis using Gas Chromatography coupled with Mass Spectrometry (GCMS).
The emerging pollutants are so defined because they have been
recognized only recently as pollutants and regulatory and monitoring plans
are not yet implemented at Italian and European level. Pharmaceuticals
and Personal Care Products (PPCPs) are considered emerging
contaminants, they describe a large class of chemical contaminants that
can originate from human usage and excretions and veterinary
applications. There are a large number of different substances used as
medicines, during and after treatment, humans and animals excrete a
combination of intact and metabolised pharmaceuticals, many of which are
generally soluble in water and have been discharged to the aquatic
environment with little evaluation of possible risks or consequences to
humans and environment. In addition, the chemicals that are components
of personal care products (PCPs) number in the thousands, the world’s
people consume enormous quantities of skin care products, dental care
products, soaps, sunscreen agents, and hair styling products. PCPs
continuously enter the wastewater after their regular use during showering
or bathing. Recent studies indicate the potential widespread occurrence on
low-level concentrations (ng-μg/L) of PPCPs in the aquatic environment.
Therefore, there’s critical need for efficient and reliable analytical methods
to address the occurrence concentrations, and fate of the PPCPs in
environment. GC-MS has been the basic tool for environmental analyses of
various organic pollutants and it has been the approach of this study choice
because of its superior separation and identification capabilities.
The activity has been concentrated on the development of sample
preparation procedures that could be fast, cost-effective and environmentfriendly
for the analysis of PPCPs. It’s known that sample pre-treatment
causes an analysis bottleneck that typically accounts for over 60% of the total analysis time. The work was focused on evaluation and optimization of
different extraction techniques for treatment of water matrix.
There are fundamentally two kinds of approach for parameters
optimization. One Factor At Time (OFAT) method involves the testing of
factors, or causes, one at a time instead of all factors are changed at once.
Even more people, prominent text books and academic papers currently
favour design of experiments (DOE) approach; it’s a statistically
multivariate method for screening and/or optimization of different factors at
the same time (multiple factors are changed at once). It shows several
relevant advantages over OFAT approach: it requires less runs for the
same (sometimes more) precision in effect estimation, it can estimate
interactions and it provides a knowledge (and optimal settings of factors) in
the whole experimental domain, where OFAT can miss them. For these
reasons this approach was chosen for several published works, using in
particular Central Composite Design (CCD) or Box-Behnken Design (BBD).
Two different extraction procedure have been studied: Solid Phase
Extraction (SPE) and Solid Phase Micro Extraction (SPME). The first
technique was evaluated in order to optimize extraction step of 25 PCPs,
including fragrances, PAHs, antioxidants, UV-filters, plasticizers, and
pesticides, from water, using OFAT approach. The optimized parameters
were different: SPE sorbent, type and volume of eluent, elution rate, and
evaporation procedure. The better recovery yield considering the totality of
PCPs were found extracting with a Strata-X SPE cartridge, using a volume
of 15 mL of Ethyl Acetate as solvent, operating with slow flow rate, and
evaporating at 40°C of temperature. Under these con ditions the procedure
achieves a recovery higher than 70% for most PCPs investigated (with
LOD ranged from 5 to 10 pg injected on GC), this result makes the
developed method suitable for comprehensive chemical profiling of PCPs in
various aqueous matrices. It is clear that higher recovery values can be
achieved only for selected PCPs using specific target-compound methods.
That it was done for method optimization for determination of two synthetic
phenolic antioxidants and their five main metabolites in water. This is the first published method dedicated solely to the determination of this
chemical class in water samples. The methodology was developed using
SPE approach with derivatization before GC-MS analysis. Extraction on 10
mg Oasis HLB cartridges provides a satisfactory enrichment factor for
environmental samples avoiding the need of solvent evaporation and
reducing SPE costs and organic solvent wastes. After extraction, polar
metabolites are derivatized with MTBSTFA to produce stable, less polar
analytes that are determined by GC-MS at low levels. The usage of two
surrogate internal standards results in a method providing good accuracy,
with relative recoveries between 80 and 110%, and limits of detection (2-44
ng/L). The application of the method to wastewater and river samples
showed BHT and BHT-Q as the compounds in higher concentrations in
wastewater (up to 800 ng/L) and the metabolites BHT-CHO and BHTCOOH
as the most resistant to water treatment, being at the 10-100 ng/L in
sewage and river samples. In this work the optimization was done with an
experimental design approach, using a Box-Behnken design (BBD). This
work was developed in collaboration with University of Santiago de
Compostela (E).
SPME technique was investigated in order to extract a mixture of several
PCPs, evaluating extraction time and temperature and desorption time and
temperature. A simple SPME method has been developed for the
simultaneous GC-MS determination of 23 PCPs (i.e. antioxidants, PAHs,
UV-filters, pesticides, fragrances, plasticizers, that display log Kow values >
3.2) at trace levels in water. An Inscribed Central Composite (CCI) design
approach was employed for investigate extraction temperature and time,
and desorption temperature and time. A direct immersion mode was used
for extraction from a fixed sample volume. The optimum SPME operating
conditions have been defined as: extraction time of 90 min at a temperature
of 80°C, desorption time of 11 min at 260°C. Under these conditions the
procedure provides low detection limits (<= ppb) and satisfactory
reproducibility (RSD%<=1%) for most of the PCPs investigated.
The analysis was then extended to more polar compounds, for a total of 21
PPCPs that display a range of log Kow between 1.2 and 6.4 (i.e. antiseptic,
antinflammatory drugs, estrogens, UV-filters) with the necessity of
derivatize the compounds before GC analysis. A on-fiber after extraction
approach was chosen for SPME derivatization, using silylation agent. The
derivatization can be performed in only 30.5 minutes with a very small
consumption of silylation reagent and without need of high temperature.
Under the optimized conditions of extraction, derivatization and desorption,
the procedure provides low detection limits (<= 1 ppb for the non polar
analytes and <=35 ppb for the derivatized ones) and satisfactory
reproducibility (RSD% <=10% or 20%) for most of the PPCPs investigated.
The PhD project, in his totality, was a logic progressive work, expanding the
study in term of kind of analytes studied, extraction techniques and
optimization approach. A preliminary and careful study was carried out in
order to properly understand the current situation and the possible research
developments of interest. The study was initially focused on less polar
analytes (PCPs), then extending to more polar ones (PPCPs). It was firstly
took in consideration the SPE technique, going to more innovative and
preferable on several points of view SPME. The expanded range (in
particular polarity range) of analytes makes necessary a derivatization step
before GC-MS analysis, for these reason the subsequent step was the
optimization of a method that includes SPME-derivatization. Also
considering the optimization approach, the work started using OFAT
optimization, this approach was left after the first work for the more
accurate and precise DOE.
These works led to development of multiresidual analytical method suitable
for the comprehensive analysis of this kind of pollutants in water matrix.
These methodologies may be the basis of water monitoring for temporal
and spatial changes
Enantiomeric resolution of biomarkers in space analysis: Chemical derivatization and signal processing for gas chromatography–mass spectrometry analysis of chiral amino acids
No full textThe work compares two GC–MS methods for enantioselective separation of amino acids as suitable candidate for stereochemical analysis of chiral amino acids on board spacecrafts in space exploration missions of solar system body environments. Different derivatization reagents are used: a mixture of alkyl chloroformate–alcohol–pyridine to obtain the alkyl alkoxy carbonyl esters and a mixture of perfluorinated
alcohols and anhydrides to form perfluoroacyl perfluoroalkyl esters. 20 proteinogenic amino acids were derivatized with the two procedures and submitted to GC–MS analysis on a Chirasil-l-Valstationary phase.
The results were then compared in terms of the enantiomeric separation achieved and intensity of MS response. The combination of methyl chloroformate (MCF) and heptafluoro-1-butanol (HFB) allows separation of 14 enantiomeric pairs, five of which display a resolution (Rs ≥1.2) supposed
to be sufficient to quantify the enantiomeric excess. Three mixtures of trifluoroacetic (TFAA) and heptafluorobutyric
(HFBA) anhydrides were combined with the corresponding perfluorinated alcohols – TFE (2,2,2-trifluoro-1-ethanol) and HFB (2,2,3,3,4,4,4-heptafluoro-1-butanol) – to give three different
reagents (TFAA–TFE, TFAA–HFB, HFBA–HFB): the derivatives obtained show separation of the same number of proteinogenic amino acids (14 of 20) at a temperature lower than column bleeding limit (200 ◦C) and 8 of them give a separation with Rs ≥1.2. Linearity study and limit of detection (XLOD) computation
show that both methods are suitable for quantitative determination of several amino acid diastereomers
at trace level (XLOD ≈0.5 nmol as derivatized quantity).
Both the procedures were coupled with automatic data handling to increase their suitability for space analysis: the simplified data treatment is especially helpful to handle the low quality data recovered from space experiments and labor and time are saved,
as imposed by the space experiments requiring a rapid delivery of the results. To achieve this aim, a chemometric approach based on the computation of the Autocovariance Function (ACVF) was applied to extract information on the enantiomeric pairs present in the sample and the enantioseparation achieved
on the chiral column
Evaluation of a gas chromatography-mass spectrometry method for the analysis of personal care products (PCPs) in wastewater.
No full textPersonal care products (PCPs) constitute a diverse group of chemicals that have recently been recognized as emerging contaminants of the aquatic environment, where they are continually introduced primarily by both untreated and treated sewage. They include compounds belonging to different chemical classes: surfactants in detergents (alkyl benzenes), fragrances in cosmetics (nitro and polycyclic musks), antioxidants and preservatives (phenols), plasticizers (phthalates). A multi-analytical method is required to determine these compounds and their bioactive metabolites in wastewater: even if LC/MS and LC/MS/MS are the most common analytical techniques for these soluble compounds, GC/MS and GC/MS/MS are sometimes used to identify and quantify volatile compounds and metabolites, in particular when resolution is mandatory to separate isomers or congeners.
In the paper a GC/MS method is presented for the simultaneous analysis of PCPs belonging to different chemical classes in wastewaters: preconcentration and clean-up of the soluble components were performed using solid-phase extraction (SPE) prior to GC-MS determination. Due to the complexity of the aquatic environment where PCPs are introduced as complex mixtures, the chromatograms obtained from wastewater samples are complex signals whose interpretation can be difficult and time-consuming. Therefore, a signal processing procedure can be helpful to extract chemical information on the sample — number of components, abundance distribution — and separation — separation performance, retention pattern.
Different extraction procedures were tested and compared, i.e., cartridge composition, solvent type and volume used to elute analytes from the cartridge in order to develop appropriate sample preparation and GC separation conditions to separate as many as possible components of the sample. The developed method may be the basis of wastewater monitoring for temporal and spatial changes of both target and non-target compounds. It will be also applied to monitoring the fate of PCPs in the wastewater treatment plant (WWTP) effluent to evaluate removal efficiency of PCPs in innovative treatment, i.e., constructed wetlands using natural processes involving wetland vegetation, filling media and their associated microbial colonias
GC-MS analytical methods for the determination of personal-care products in water matrices
No full textThis article discusses the more recent methods combining gas chromatography and mass spectrometry (GC-MS) for analysis of personal-care products (PCPs) in water matrices. We describe different procedures for sample extraction and preparation as well as different instrumental methods commonly used for these compounds. GC-MS and GC-tandem MS (GC-MS2), which are complementary to liquid chromatography combined with MS (LC-MS), allow identification and quantification of PCPs belonging to different classes with the sensitivity and the selectivity necessary for environmental monitoring.
The compounds investigated include fragrances (e.g., nitro and polycyclic musks), antimicrobial compounds (e.g., triclosan), ultraviolet blockers (e.g., methylbenzylidene camphor), antioxidants and preservatives (e.g., phenols and p-hydroxybenzoic acid (parabens)) and insect repellents (e.g., N,N-diethyl- m-toluamide (DEET)). We critically review data in the literature by focusing attention on analytical methods devoted to simultaneous detection and quantification of structurally diverse pharmaceuticals and PCPs
DEVELOPMENT OF A SPME/GC/MS METHOD FOR THE SIMULTANEOUS DETERMINATION OF PHARMACEUTICALS AND PERSONAL CARE PRODUCTS IN ENVIRONMENTAL WATERS
No full textPharmaceuticals and personal care products (PPCPs) constitute a broad class of emerging contaminants, belonging to the list of high production volume chemicals that are currently used for human and veterinary application (e.g., pharmaceuticals, sunscreens, cosmetics, insect repellents, and soaps).
These substances have been continuously discharged to the aquatic environment, with resulting environmental and human health impact.
In this work, a headspace solid phase microextraction (HS-SPME) method coupled with gas chromatography and MS detection (GC/MS) was optimized for the simultaneous determination of 21 target PPCPs in water samples. The analytes included fragrances, UV-filters, antiseptics, estrogens, anti-inflammatory drugs and pesticides. SPME is an environmentally-friendly alternative to the common approaches, because it achieves extraction and clean-up in a single step eliminating the need for solvents and expensive equipments.
An on-fiber SPME derivatization, using silyl reagents, was performed for the analysis of more polar acidic compounds. An experimental design approach was applied to systematically
investigate and optimize the operative parameters affecting the extraction recovery: extraction temperature and time, derivatization time, desorption temperature and time. The optimal conditions were: extraction time of 125min at 40°C; derivatization time of 30.5 min; desorption time of 2 min at
300°C. Under these conditions, good repeatability was assessed as RDS% values ≤ 10% for underivatized PPCPs and ≤ 20% for derivatized ones. The method detection limits were between 0.7 and 9.0 ng L-1, with the highest values in the range 2.5-9.0 ng L-1 for the derivatized analytes. Method accuracy was evaluated on spiked tap water samples: recoveries varied from
85 to 103% and from 75 to 110 % for non derivatized and derivatized compounds, respectively. The results obtained indicate the potentiality of the method for the determination of the investigated analytes at trace levels
Analisi di contaminanti emergenti: messa a punto di un metodo multiresiduo GC-MS per l'analisi di PCPs (Personal Care Products) nelle acque
No full textI componenti chimici presenti nei prodotti per la cura e l’igiene personale (PCPs), riconosciuti come contaminanti emergenti e persistenti nell’ambiente, includono un’ampia e diversificata gamma di sostanze chimiche: tensioattivi, profumi, filtri UV, antibatterici, conservanti [1,2].
Sono definiti emergenti in quanto sono stati riconosciuti solo recentemente come agenti inquinanti e, a livello nazionale ed europeo, ne sono previsti regolamentazione e monitoraggio ancora non attuati. Sono inquinanti che persistono nell’ambiente grazie al loro continuo rilascio; hanno, si può dire, una “pseudo-persistenza”, con significative conseguenze sull’ambiente [2].
Tra le principali problematiche relative a questi composti vi è la necessità di definire metodiche analitiche di monitoraggio adeguate. Un singolo metodo di analisi per differenti classi di composti risulta molto vantaggioso per il loro monitoraggio, in quanto riduce i tempi di analisi, il numero di campioni da prelevare e i costi.
Si è messo a punto un metodo multiresiduo che utilizza Gas Cromatografia-Spettrometria di Massa (GC-MS) per l'analisi simultanea di PCPs volatili appartenenti a classi diverse e presenti in tracce in matrici acquose ambientali.
Il campione è purificato e preconcentrato usando estrazione in fase solida (SPE) prima dell’analisi GC-MS. Dopo un preliminare studio bibliografico [3], sono stati valutati due tipi di cartucce SPE: C-18 (Restek) e STRATA-X (Phenomenex), con caratteristiche sia lipofile che idrofile. Sono stati esaminati e confrontati diversi eluenti, volumi di eluente e altre condizioni per la preconcentrazione del campione.
Sono state ottimizzate le condizioni operative d’analisi tramite GC, per separare il maggior numero di componenti possibili nel campione. Il metodo è stato testato su 29 composti target rappresentativi delle diverse classi di PCPs.
Si è osservato che le rese di estrazione risultano più elevate utilizzando cartucce STRATA-X, eluendo con 15 ml di Etilacetato, con rese medie > 75% (figura 1)
GC-MS multiresidue method for the analysis of Personal Care Products (PCPs) in wastewaters
No full textPersonal Care Products (PCPs) constitute a diverse group of chemicals that have recently been recognized as particular contaminants of the aquatic environment, where they are continually introduced as complex mixtures primarily by both untreated and treated sewage [1]. Though most of the published methods are devoted to a small number of PCPs belonging to the same chemical class, a multi-analytical method is relevant to simultaneously determine many PCPs and their bioactive metabolites displaying a wide range of physico-chemical properties, i.e., volatility, polarity, water solubility [2].
In this work a GC-MS multi-residue method has been developed for the simultaneous analysis of PCPs belonging to different chemical classes in wastewaters: the preliminary step for pre-concentration and clean-up of the complex sample prior to GC-MS analysis has been investigated and optimized using the SPE (solid-phase extraction) procedure. The work was focused on 31 target compounds properly selected to represent different chemical classes of PCPs occurring in wastewaters: nitro and polycyclic musks (fragrances in cosmetics), phenols (antioxidants and preservatives), phthalates (plasticizers).
Different SPE adsorbents and eluting conditions were tested and compared: in addition to the conventional stationary phase, a surface modified styrene divinylbenzene polymeric phase ( SPE cartridge) has been investigated as properly suitable for polar and non-polar compounds. Different solvent compositions and eluting conditions were tested to achieve the best recovery for all the target analytes. With the optimized experimental procedure most of the PCPs can be reproducibly extracted with high recoveries (above 80%).
In the GC-MS analysis, the high complexity of the GC-MS signal due to the low selectivity of the extraction step can be solved by the high selectivity and sensitivity of the SIM or MS/MS detection
Signal processing to evaluate parameters affecting SPE for multi-residue analysis of personal care products
No full textThis paper discusses the development of a comprehensive method for the simultaneous analysis of Personal Care Products (PCPs) based on Solid-Phase Extraction and Gas Chromatography/Mass Spectrometry. The method was developed on 29 target compounds to represent PCPs belonging to different chemical classes displaying a wide range of volatility, polarity, water solubility: surfactants in detergents (alkyl benzenes), fragrances in cosmetics (nitro and polycyclic musks), antioxidants and preservatives (phenols), plasticizers (phthalates).
In addition to the conventional stationary phase, a surface modified styrene divinylbenzene polymeric phase ( SPE cartridge) has been investigated as suitable to for the simultaneous extraction of several PCPs with polar and non-polar characteristics. For both sorbents different solvent compositions and eluting conditions were tested and compared in order to achieve high extraction efficiency for as many sample components as possible.
Comparison of the behavior of the two cartridges reveals that, overall, provides better efficiency with extraction recovery higher than 70% for most of the PCPs investigated. The best results were obtained under the following operative conditions: an evaporation temperature of 40°C, elution on cartridge using a volume of 15 mL of ethyl acetate as solvent and operating with slow flow rate (-10 KPa).
In addition to the conventional method based on peak integration, a chemometric approach based on the computation of the Autocovariance Function ( ACVF) was applied to the complex GC-MS signal: the percentage recovery and information on peak abundance distribution can be evaluated for each procedure step. The PC-based signal processing proved very helpful in assisting the development of the analytical procedure, since it saves labor and time and increases result reliability in handling GC complex signals
Analisi di contaminanti emergenti nelle acque: messa a punto di un metodo multiresiduo GC-MS per l’analisi di PCP
No full textI componenti chimici presenti nei prodotti per la cura e l’igiene personali (PCPs, Personal Care Products) includono un’ampia e diversificata gamma di sostanze chimiche, fra cui: tensioattivi (benzeni alchilici), profumi (nitro muschi e muschi policiclici), filtri UV (benzofenone, ottocrilene), antibatterici (triclosan, clorophene), conservanti (parabeni) , . Sono definiti emergenti in quanto sono stati riconosciuti solo recentemente come agenti inquinanti e, a livello nazionale ed europeo, ne sono previsti regolamentazione e monitoraggio ancora non attuati. Sono inquinanti che persistono nell’ambiente grazie al loro continuo rilascio; hanno, si può dire, una “pseudo-persistenza”, con significative conseguenze sull’ambiente .
Tra le principali problematiche relative a questi composti vi è la necessità di definire metodiche analitiche di monitoraggio adeguate. Un singolo metodo di analisi per differenti classi di composti è molto vantaggioso, in quanto riduce i tempi di analisi, il numero di campioni da prelevare e i costi.
Si sta lavorando alla messa a punto di un metodo multiresiduo che utilizza Gas Cromatografia-Spettrometria di Massa (GC-MS) per l'analisi simultanea di PCPs volatili appartenenti a classi diverse in matrici acquose ambientali. Il campione è purificato e preconcentrato usando estrazione in fase solida (SPE) prima dell’analisi GC-MS. Dopo un preliminare studio bibliografico , sono state esaminate e confrontate differenti condizioni di estrazione: la composizione della cartuccia, il tipo ed il volume del solvente utilizzato per eluire gli analiti da questa. L’obiettivo di questa ricerca è mettere a punto un metodo analitico in grado d’estrarre e concentrare composti PCPs presenti in tracce in acqua. Sono state valutate cartucce SPE C-18 (Restek) e STRATA-X (Phenomenex), quest’ultima con caratteristiche sia lipofile che idrofile, con diversi eluenti ognuna. Sono state ottimizzate le condizioni operative d’analisi tramite GC, per separare il maggior numero di componenti possibili nel campione. Il metodo è stato testato su 30 composti target
- …
