967 resultados para Liquid liquid extraction


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An analytical method based on liquid chromatography with positive ion electrospray ionization (ESI) coupled to tandem mass spectrometry detection was developed for the determination of pantoprazole (CAS 102625-70-7) in human plasma using lansoprazole (CAS 103577-45-3) as the internal standard. The analyte and internal standard were extracted from the plasma samples by liquid/liquid extraction using diethyl-ether/dichloromethane (70:30; v/v) and chromatographed on a C-8 analytical column. The mobile phase consisted of acetonitrile/water/methanol (57:25:18; v/v/v) + 10 mmol/l acetic acid + 20 mmol/l ammonium acetate. The method has a chromatographic total run time of 4.5 min and was linear within the range 5.0-5,000 ng/mL. Detection was performed on a triple quadrupole tandem mass spectrometer by Multiple Reaction Monitoring (MRM). The intra- and inter-run precisions calculated from quality control (QC) samples were 4.2% and 3.2%, respectively. The accuracies as determined from QC samples were -5.0% (intra-run) and 2.0% (inter-run). The method herein described was employed in a bioequivalence study of two tablet formulations of pantoprazole.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Liquid-liquid extraction is utilized for purification of biomolecules by Aqueous Biphasic Systems (ABS), since this process does not damage the biotechnological potential of these compounds. In this work, using the free software Scilab®, the fractionated liquid-liquid extraction was studied aiming a lipase (target enzyme) partition in a water + PEG + DEX system. Lisozime was considered as contaminant. As computer simulations has been extensively used when a first estimation of technical feasibility of process is desired, this work demonstred that the system is viable for recovery the 80 % till 90 % the target enzyme, but should be noted that the trial aimed only the fractionation of the enzyme target of a contaminant, not its concentration, which should be done by another process.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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In the present study, a fast, sensitive and robust method to quantify dextromethorphan, dextrorphan and doxylamine in human plasma using deuterated internal standards (IS) is described. The analytes and the IS were extracted from plasma by a liquid-liquid extraction (LLE) using diethyl-ether/hexane (80/20, v/v). Extracted samples were analyzed by high performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Chromatographic separation was performed by pumping the mobile phase (acetonitrile/water/formic acid (90/9/1, v/v/v) during 4.0 min at a flow-rate of 1.5 mL min(-1) into a Phenomenex Gemini (R) C18, 5 mu m analytical column (150 x 4.6 mm id.). The calibration curve was linear over the range from 0.2 to 200 ng mL(-1) for dextromethorphan and doxylamine and 0.05 to 10 ng mL(-1) for dextrorphan. The intra-batch precision and accuracy (%CV) of the method ranged from 2.5 to 9.5%, and 88.9 to 105.1%, respectively. Method inter-batch precision (%CV) and accuracy ranged from 6.7 to 10.3%, and 92.2 to 107.1%, respectively. The run-time was for 4 min. The analytical procedure herein described was used to assess the pharmacokinetics of dextromethorphan, dextrorphan and doxylamine in healthy volunteers after a single oral dose of a formulation containing 30 mg of dextromethorphan hydrobromide and 12.5 mg of doxylamine succinate. The method has high sensitivity, specificity and allows high throughput analysis required for a pharmacokinetic study. (C) 2012 Elsevier B.V. All rights reserved.

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This study describes the enantioselective analysis of unbound and total concentrations of tramadol and its main metabolites O-desmethyltramadol (M1) and N-desmethyltramadol (M2) in human plasma. Sample preparation was preceded by an ultrafiltration step to separate the unbound drug. Both the ultrafiltrate and plasma samples were submitted to liquid/liquid extraction with methyl t-butyl ether. Separation was performed on a Chiralpak (R) AD column and tandem mass spectrometry consisting of an electrospray ionization source, positive ion mode and multiple reaction monitoring was used as the detection system. Linearity was observed in the following ranges: 0.2-600 and 0.5-250 ng/mL for analysis of total and unbound concentrations of the tramadol enantiomers, respectively, and 0.1-300 and 0.25-125 ng/mL for total and unbound concentrations of the M1 and M2 enantiomers, respectively. The lower limits of quantitation were 0.2 and 0.5 ng/mL for analysis of total and unbound concentration of each tramadol enantiomer, respectively, and 0.1 and 0.25 ng/mL for total and unbound concentrations of M1 and M2 enantiomers, respectively. Intra- and interassay reproducibility and inaccuracy did not exceed 15%. Clinical application of the method to patients with neuropathic pain showed plasma accumulation of (+)-tramadol and (+)-M2 after a single oral dose of racemic tramadol. Fractions unbound of tramadol, M1 or M2 were not enantioselective in the patients investigated. (C) 2011 Elsevier B.V. All rights reserved.

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An high performance liquid chromatography (HPLC) method for the enantioselective determination of donepezil (DPZ), 5-O-desmethyl donepezil (5-ODD), and 6-O-desmethyl donepezil (6-ODD) in Czapek culture medium to be applied to biotransformation studies with fungi is described for the first time. The HPLC analysis was carried out using a Chiralpak AD-H column with hexane/ethanol/methanol (75:20:5, v/v/v) plus 0.3 % triethylamine as mobile phase and UV detection at 270 nm. Sample preparation was carried out by liquid-liquid extraction using ethyl acetate as extractor solvent. The method was linear over the concentration range of 100-10,000 ng mL(-1) for each enantiomer of DPZ (r a parts per thousand yenaEuro parts per thousand 0.9985) and of 100-5,000 ng mL(-1) for each enantiomer of 5-ODD (r a parts per thousand yenaEuro parts per thousand 0.9977) and 6-ODD (r a parts per thousand yenaEuro parts per thousand 0.9951). Within-day and between-day precision and accuracy evaluated by relative standard deviations and relative errors, respectively, were lower than 15 % for all analytes. The validated method was used to assess DPZ biotransformation by the fungi Beauveria bassiana American Type Culture Collection (ATCC) 7159 and Cunninghamella elegans ATCC 10028B. Using the fungus B. bassiana ATCC 7159, a predominant formation of (R)-5-ODD was observed while for the fungus C. elegans ATCC 10028B, DPZ was biotransformed to (R)-6-ODD with an enantiomeric excess of 100 %.

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The olive oil extraction industry is responsible for the production of high quantities of vegetation waters, represented by the constitutive water of the olive fruit and by the water used during the process. This by-product represent an environmental problem in the olive’s cultivation areas because of its high content of organic matter, with high value of BOD5 and COD. For that reason the disposal of the vegetation water is very difficult and needs a previous depollution. The organic matter of vegetation water mainly consists of polysaccharides, sugars, proteins, organic acids, oil and polyphenols. This last compounds are the principal responsible for the pollution problems, due to their antimicrobial activity, but, at the same time they are well known for their antioxidant properties. The most concentrate phenolic compounds in waters and also in virgin olive oils are secoiridoids like oleuropein, demethyloleuropein and ligstroside derivatives (the dialdehydic form of elenolic acid linked to 3,4-DHPEA, or p-HPEA (3,4-DHPEA-EDA or p-HPEA-EDA) and an isomer of the oleuropein aglycon (3,4-DHPEA-EA). The management of the olive oil vegetation water has been extensively investigated and several different valorisation methods have been proposed, such as the direct use as fertilizer or the transformation by physico-chemical or biological treatments. During the last years researchers focused their interest on the recovery of the phenolic fraction from this waste looking for its exploitation as a natural antioxidant source. At the present only few contributes have been aimed to the utilization for a large scale phenols recovery and further investigations are required for the evaluation of feasibility and costs of the proposed processes. The present PhD thesis reports a preliminary description of a new industrial scale process for the recovery of the phenolic fraction from olive oil vegetation water treated with enzymes, by direct membrane filtration (microfiltration/ultrafiltration with a cut-off of 250 KDa, ultrafiltration with a cut-off of 7 KDa/10 KDa and nanofiltration/reverse osmosis), partial purification by the use of a purification system based on SPE analysis and by a liquid-liquid extraction system (LLE) with contemporary reduction of the pollution related problems. The phenolic fractions of all the samples obtained were qualitatively and quantitatively by HPLC analysis. The work efficiency in terms of flows and in terms of phenolic recovery gave good results. The final phenolic recovery is about 60% respect the initial content in the vegetation waters. The final concentrate has shown a high content of phenols that allow to hypothesize a possible use as zootechnic nutritional supplements. The purification of the final concentrate have garanteed an high purity level of the phenolic extract especially in SPE analysis by the use of XAD-16 (73% of the total phenolic content of the concentrate). This purity level could permit a future food industry employment such as food additive, or, thanks to the strong antioxidant activity, it would be also use in pharmaceutical or cosmetic industry. The vegetation water depollutant activity has brought good results, as a matter of fact the final reverse osmosis permeate has a low pollutant rate in terms of COD and BOD5 values (2% of the initial vegetation water), that could determinate a recycling use in the virgin olive oil mechanical extraction system producing a water saving and reducing thus the oil industry disposal costs .

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Die vorliegende Arbeit beschäftigt sich vorwiegend mit Detektionsproblemen, die bei Experimenten zur Chemie der Transactiniden mit dem schnellen Flüssig-Flüssig-Extraktionssystem SISAK auftraten. Bei diesen Experimenten wird als Detektionsmethode die Flüssigszintillationsspektroskopie (LSC) eingesetzt. Es werden Szintillationspulse registriert, die für das verursachende Teilchen charakteristische Formen zeigen, die unterschieden werden müssen. Am Beispiel der Auswertung des SISAK-Experimentes zur Chemie des Rutherfordiums vom November 1998 wurde gezeigt, dass es mit den herkömmlichen Verfahren zur Pulsformdiskriminierung nicht möglich ist, die aus dem Zerfall der Transactiniden stammenden alpha-Ereignisse herauszufiltern. Ursache dafür ist ein hoher Untergrund, der in erster Linie von beta/gamma-Teilchen, Spaltfragmenten und pile ups verursacht wird. Durch die Verfügbarkeit von Transientenrecordern ergeben sich neue Möglichkeiten für eine digitale Pulsformdiskriminierung. In dieser Arbeit wird erstmals die Methode der digitalen Pulsformdiskriminierung mit künstlichen neuronalen Netzen (PSD-NN) vorgestellt. Es wurde im Zuge der Auswertung des SISAK-Experimentes vom Februar 2000 gezeigt, dass neuronale Netze in der Lage sind, Pulsformen automatisch richtig zu klassifizieren. Es ergeben sich nahezu untergrundfreie alpha-Flüssigszintillationsspektren. Es werden Vor- und Nachteile der neuen Methode diskutiert. Es ist dadurch möglich geworden, in SISAK-Experimenten Transactinidenatome anhand ihres Zerfalls eindeutig zu charakterisieren. Das SISAK-System kann somit bei Experimenten zum Studium des chemischen Verhaltens von Transactiniden in flüssiger Phase eingesetzt werden.____

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Im Rahmen dieser Arbeit wurden Experimente auf verschiedenen Gebieten der chemischen Charakterisierung der schwersten Elemente durchgeführt. So wurden Vorarbeiten zur Elektrochemie der superschweren Elemente geleistet. Hier konnte gezeigt werden, dass sich Po aus verdünnten Säuren auf Metallelektroden spontan abscheiden lässt. Als wichtigste Reaktionsparameter wurden Temperatur, Konvektion und Viskosität des Elektrolyten identifiziert. Für die Elektrodeposition ist es von Bedeutung, reproduzierbar saubere Elektroden einzusetzen. Auch hierzu konnten Erkenntnisse gewonnen werden. Auf dem Gebiet der Charakterisierung von Nukliden wurde der Elektroneneinfang in Db-263 untersucht. Aus diesem Zerfall geht Rf-263 hervor, welches mit einer Halbwertszeit von 15min überwiegend durch Spontanspaltung zerfällt. Im Experiment wurde Rf-263 mittels Ionenaustauschchromatographie und nachfolgender Flüssig-Flüssig-Extraktion von Db und Aktiniden getrennt. Das erhaltene Präparat wurde auf Alpha-Zerfall und Spontanspaltung untersucht. Die Zahl der Rf-263 Zerfälle lässt auf einen Zerfallszweig durch Elektroneneinfang in Db-263 von 3% schließen. Ein Großteil der Arbeit beschäftigt sich mit der Bestimmung des Kd-Wertes von Sg am Anionenaustauscher Aminex A27 in 0.1M HNO3/5E-3M HF. Beim mit dem ALOHA-System durchgeführten Experiment wurde die Mehrsäulentechnik (MCT) erstmals für die wässrige Chemie von Sg genutzt. Aufgrund zahlreicher Probleme konnte letztlich kein Kd-Wert bestimmt werden. Stattdessen wurde das Experiment einer Fehleranalyse unterzogen. Hier zeigte sich eine Anfälligkeit der MCT auf natürliche Radionuklide. Weiterhin konnten Probleme bei ALOHA aufgedeckt werden, die eine Wiederholung des Experiments ausschlossen. In der Folge wurde ein alternativer Anionenaustauscher charakterisiert, sowie die Elektrolysebedingungen, als wichtiger Schritt der chemischen Aufarbeitung bei der MCT, genauer spezifiziert.

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An accurate and sensitive species-specific GC-ICP-IDMS (gas chromatography inductively coupled plasma isotope dilution mass spectrometry) method for the determination of trimethyllead and a multi-species-specific GC-ICP-IDMS method for the simultaneous determination of trimethyllead, methylmercury, and butyltins in biological and environmental samples were developed. They allow the determination of corresponding elemental species down to the low ng g-1 range. The developed synthesis scheme for the formation of isotopically labeled Me3206Pb+ can be used for future production of this spike. The novel extraction technique, stir bar sorptive extraction (SBSE), was applied for the first time in connection with species-specific isotope dilution GC-ICP-MS for the determination of trimethyllead, methylmercury and butyltins. The results were compared with liquid-liquid extraction. The developed methods were validated by the analysis of certified reference materials. The liquid-liquid extraction GC-ICP-IDMS method was applied to seafood samples purchased from a supermarket. The methylated lead fraction in these samples, correlated to total lead, varied in a broad range of 0.01-7.6 %. On the contrary, the fraction of methylmercury is much higher, normally in the range of 80-98 %. The highest methylmercury content of up to 12 µg g-1 has been determined in shark samples, an animal which is at the end of the marine food chain, whereas in other seafood samples a MeHg+ content of less than 0.2 µg g-1 was found. Butyltin species could only be determined in samples, where anthropogenic contaminations must be assumed. This explains the observed broad variation of the butylated tin fraction in the range of <0.3-49 % in different seafood samples. Because all isotope-labelled spike compounds, except trimethyllead, are commercially available, the developed multi-species-specific GC-ICP-IDMS method has a high potential in future for routine analysis.

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Das Element Arsen besitzt eine Reihe von Isotopen, die in nahezu trägerfreier Form (nca) produziert werden können und deshalb in der Radiopharmazie für die Diagnose oder Endoradiotherapie Verwendung finden können. Bei der Positronenemissionstomographie (PET) gibt es eine gewisse Lücke bei der Versorgung mit langlebigen Positronenemittern, die zur Untersuchung von langsamen physiologischen Prozessen wie z.B. der Biodistribution und Anreicherung von Antikörpern in Tumorgewebe eingesetzt werden können. Die beiden Arsenisotope 72As (T1/2 = 26 h, 88 % beta+) und 74As (T1/2 = 17,8 d, 29 % beta+) vereinen eine lange physikalische Halbwertszeit mit einer hohen Positronenemissionsrate und sind daher geeignete Kandidaten. Da das Verhalten von radioaktivem Arsen und seine Verwendung in der molekularen Bildgebung international relativ wenig bearbeitet sind, wurde die Radiochemie des Arsens von der Isotopenproduktion an Kernreaktor und Zyklotron, über die Entwicklung von Abtrennungsmethoden für Germanium und Arsen, bis hin zur Entwicklung einer soliden Markierungschemie für Antikörper weiterentwickelt. Die in dieser Arbeit bearbeiteten Felder sind: 1. Die Isotopenproduktion der relevanten Arsenisotope (72/74/77As) wurde an Kernreaktor und Zyklotron durch Bestrahlung von GeO2- und Germaniummetalltargets durchgeführt. Pro 6 h Bestrahlung von 100 mg Germanium konnten ca. 2 MBq 77As am TRIGA Reaktor in Mainz hergestellt werden. Am Zyklotron des DKFZ in Heidelberg konnten unter optimierten Bedingungen bei der Bestrahlung von Germaniummetall (EP = 15 Mev, 20 µA, 200 µAh) ca. 4 GBq 72As und ca. 400 MBq 74As produziert werden. 2. Die Entwicklung neuer Abtrennungsmethoden für nca 72/74/77As von makroskopischen Mengen Germanium wurde vorangetrieben. Für die Aufarbeitung von GeO2- und Germaniummetalltargets kamen insgesamt 8 verschiedene Methoden wie Festphasenextraktion, Flüssig-Flüssig-Extraktion, Destillation, Anionenaustauschchromatographie zum Einsatz. Die erzielten Ausbeuten lagen dabei zwischen 31 und 56 %. Es wurden Abtrennungsfaktoren des Germaniums zwischen 1000 und 1•10E6 erreicht. Alle erfolgreichen Abtrennungsmethoden lieferten *As(III) in 500 µl PBS-Puffer bei pH 7. Diese Form des Radioarsens ist für die Markierung von SH-modifizierten Molekülen, wie z.B. Antikörpern geeignet. 3. Die Entwicklung von Methoden zur Bestimmung des Oxidationszustandes von nca *As in organischem, neutralem wässrigen, oder stark sauren Medium mittels Radio-DC und Anionenaustauschchromatographie wurde durchgeführt und führte zu einem besseren Verständnis der Redoxchemie des nca *As. 4. SH-modifizierte Antikörper wurden mit 72/74/77As(III) markiert. Dabei wurden zwei Methoden (Modifizierung mit SATA und TCEP) miteinander verglichen. Während das *As(III) bei Verwendung von TCEP in Ausbeuten > 90 % mit dem Antikörper reagierte, wurde für SATA-modifizierte Antikörper in Abhängigkeit von der verwendeten Abtrennungsmethode eine breite Spanne von 0 % bis > 90 % beobachtet. 5. Es wurden Phantommessungen mit 18F, 72As und 74As am µ-PET-Scanner durchgeführt, um erste Aussagen über die zu erwartende Auflösung der Arsenisotope zu erhalten. Die Auflösung von 74As ist mit 18F vergleichbar, während die von 72As erkennbar schlechter ist.

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In spite of the higher toxicity of oxygen-containing polycyclic aromatic hydrocarbons (OPAHs) than of their parent-PAHs, there are only a few studies of the concentrations, composition pattern, sources and fate of OPAHs in soil, the presumably major environmental sink of OPAHs. This is related to the fact that there are only few available methods to measure OPAHs together with PAHs in soil. rnThe objectives of my thesis were to (i) develop a GC/MS-based method to measure OPAHs and their parent-PAHs in soils of different properties and pollution levels, (ii) apply the method to soils from Uzbekistan and Slovakia and (iii) investigate into the fate of OPAHs, particularly their vertical transport in soilrnI optimized and fully evaluated an analytical method based on pressurized liquid extraction, silica gel column chromatographic fractionation of extracted compounds into alkyl-/parent-PAH and OPAH fractions, silylation of hydroxyl-/carboxyl-OPAHs with N,O-bis(trimethylsilyl)trifluoracetamide and GC/MS quantification of the target compounds. The method was targeted at 34 alkyl-/parent-PAHs, 7 carbonyl-OPAHs and 19 hydroxyl-/carboxyl-OPAHs. I applied the method to 11 soils from each of the Angren industrial region (which hosts a coal mine, power plant, rubber factory and gold refinery) in Uzbekistan and in the city of Bratislava, the densely populated capital of Slovakia.rnRecoveries of five carbonyl-OPAHs in spike experiments ranged between 78-97% (relative standard deviation, RSD, 5-12%), while 1,2-acenaphthenequinone and 1,4-naphtho-quinone had recoveries between 34-44%% (RSD, 19-28%). Five spiked hydroxyl-/carboxyl-OPAHs showed recoveries between 36-70% (RSD, 13-46%), while others showed recoveries &amp;amp;lt;10% or were completely lost. With the optimized method, I determined, on average, 103% of the alkyl-/parent-PAH concentrations in a certified reference material.rnThe ∑OPAHs concentrations in surface soil ranged 62-2692 ng g-1 and those of ∑alkyl-/parent-PAHs was 842-244870 ng g-1. The carbonyl-OPAHs had higher concentrations than the hydroxyl-/carboxyl-OPAHs. The most abundant carbonyl-OPAHs were consistently 9-fluorenone (9-FLO), 9,10-anthraquinone (9,10-ANQ), 1-indanone (1-INDA) and benzo[a]anthracene-7,12-dione (7,12-B(A)A) and the most abundant hydroxyl-/carboxyl-OPAH was 2-hydroxybenzaldehyde. The concentrations of carbonyl-OPAHs were frequently higher than those of their parent-PAHs (e.g., 9-FLO/fluorene &amp;amp;gt;100 near a rubber factory in Angren). The concentrations of OPAHs like those of their alkyl-/parent-PAHs were higher at locations closer to point sources and the OPAH and PAH concentrations were correlated suggesting that both compound classes originated from the same sources. Only for 1-INDA and 2-biphenylcarboxaldehyde sources other than combustion seemed to dominate. Like those of the alkyl-/parent-PAHs, OPAH concentrations were higher in topsoils than subsoils. Evidence of higher mobility of OPAHs than their parent-PAHs was provided by greater subsoil:topsoil concentration ratios of carbonyl-OPAHs (0.41-0.82) than their parent-PAHs (0.41-0.63) in Uzbekistan. This was further backed by the consistently higher contribution of more soluble 9-FLO and 1-INDA to the ∑carbonyl-OPAHs in subsoil than topsoil at the expense of 9,10-ANQ, 7,12-B(A)A and higher OPAH/parent-PAH concentration ratios in subsoil than topsoil in Bratislava.rnWith this thesis, I contribute a suitable method to determine a large number of OPAHs and PAHs in soil. My results demonstrate that carbonyl-OPAHs are more abundant than hydroxyl-/carboxyl-OPAHs and OPAH concentrations are frequently higher than parent-PAH concentrations. Furthermore, there are indications that OPAHs are more mobile in soil than PAHs. This calls for appropriate legal regulation of OPAH concentrations in soil.

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Le sostanze perfluoralchiliche (PFAS), composti fluorurati ampiamente utilizzati negli ultimi anni in diverse applicazioni industriali e commerciali, sono ritrovati diffusamente nell’ambiente e in diverse specie animali. Recentemente i PFAS hanno destato preoccupazione anche per la salute umana. Il rischio di esposizione è principalmente legato alla dieta (i prodotti ittici sembrano essere gli alimenti più contaminati). Lo scopo di questo lavoro è stato quello di valutare la presenza del perfluorottanosulfonato (PFOS) e dell’acido perfluorottanoico (PFOA), in diverse matrici alimentari: latte vaccino commercialmente disponibile in Italia, latte materno italiano, diverse specie di pesce commercialmente disponibili in Italia e 140 branzini di diverse aree (principalmente Mediterraneo). I campioni di latte sono stati trattati con estrazione liquido-liquido seguita da due fasi di purificazione mediante cartucce SPE prima dell’iniezione nell’UPLC-MS/MS. L’analisi del latte vaccino ha evidenziato una contaminazione diffusa di PFOS, ma a basse concentrazioni (fino a 97 ng/L), mentre il PFOA è stato ritrovato raramente. In questo studio, in grado di individuare anche i livelli delle ultra-tracce, sono state osservate nel latte materno concentrazioni di 15-288 ng/L per il PFOS e di 24-241 ng/LPFOA. Le concentrazioni e le frequenze più alte, per entrambi i PFAS, sono stati ritrovate in campioni di latte forniti da donne primipare, suggerendo un rischio di esposizione per i primogeniti. Il metodo utilizzato per i campioni di pesce era basato su un’estrazione con solvente organico seguita da due fasi di purificazione: una con i sali e una con fase solida dispersiva. L’estratto, analizzato in UPLC-MS/MS, ha confermato la contaminazione di questa matrice a livelli significativi, ma anche l’alta variabilità delle concentrazioni misurate. Il monitoraggio monospecie ha mostrato una contaminazione rilevante (PFOS 11,1- > 10000 ng/L; PFOA < 9-487 ng/L), soprattutto nei branzini pescati, rispetto a quelli allevati.