Publications by authors named "Natalia Campillo"

71 Publications

Non-targeted analysis by DLLME-GC-MS for the monitoring of pollutants in the Mar Menor lagoon.

Chemosphere 2021 Jul 17;286(Pt 1):131588. Epub 2021 Jul 17.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100, Murcia, Spain. Electronic address:

Non-targeted analysis for the monitoring of organic pollutants resulting from agricultural and industrial practices, plastics and pharmaceutical products of seawater from the Mar Menor lagoon (SE Spain) is proposed using dispersive liquid-liquid microextraction (DLLME) and gas chromatography-mass spectrometry (GC-MS). Initially, a home-made MS database including 118 environmental organic pollutants, whose presence in different ecosystems has already been reported, was created. The analytical method was applied for the analysis of 42 samples and a total of 18 pollutants were detected and identified. Samples were obtained from different sites around the Mar Menor in three sampling campaigns, enabling the assessment of impact of rain on the input of the detected chemicals and their distribution. In addition, this methodology was validated using a standard mixture containing 54 of the environmental pollutants included in the database, allowing the quantification of the 9 of the identified compounds (dibutyl phthalate, diisobutyl phthalate, diethyl phthalate, bis(2-ethylhexyl) phthalate, anthracene, 2-methylnaphthalene, hexachlorocyclopentadiene, bis(2-ethylhexyl) adipate and oleamide) with concentration between 3 and 271 μg L.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131588DOI Listing
July 2021

Cellulose-ferrite nanocomposite for monitoring enniatins and beauvericins in paprika by liquid chromatography and high-resolution mass spectrometry.

Talanta 2021 May 28;226:122144. Epub 2021 Jan 28.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100, Murcia, Spain. Electronic address:

Paprika is considered a high-quality product being one of the most consumed spices in the world. Contamination with mycotoxins may appear due to inappropriate practices during processing or resulting from invading mould in the final manufactured products. A sample treatment based on dispersive magnetic solid-phase extraction (DMSPE) has been proposed for emerging mycotoxin determination, enniatins (ENNs) and beauvericins (BEAs), in paprika. Different magnetic nanoparticles were tested, and cellulose-ferrite nanocomposite was selected for the extraction and preconcentration of the mycotoxins. Nanocomposite was characterised using field emission scanning electron microscopy and energy dispersive X-ray spectroscopy in terms of morphology and elemental composition. High-resolution mass spectrometry allowed the quantification of the five main emerging mycotoxins and the monitoring of unexpected members of this class of toxic fungal secondary metabolites. The method has been validated, obtaining limits of quantification between 9.5 and 9.9 μg kg and testing its trueness through recovery studies, with satisfactory values of between 89.5 and 97.7%. Relative standard deviations were calculated to evaluate the intra- and inter-day precision and values lower than 8% were obtained in all cases. The analysis of 26 samples, including conventional and organic, demonstrated the presence of ENNB1 at 12.0 ± 0.6 μg kg in one of the samples studied. Other analogues ENNs and BEAs were not detected.
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http://dx.doi.org/10.1016/j.talanta.2021.122144DOI Listing
May 2021

Monitoring Lipophilic Toxins in Seawater Using Dispersive Liquid-Liquid Microextraction and Liquid Chromatography with Triple Quadrupole Mass Spectrometry.

Toxins (Basel) 2021 01 13;13(1). Epub 2021 Jan 13.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain.

The use of dispersive liquid-liquid microextraction (DLLME) is proposed for the preconcentration of thirteen lipophilic marine toxins in seawater samples. For this purpose, 0.5 mL of methanol and 440 µL of chloroform were injected into 12 mL of sample. The enriched organic phase, once evaporated and reconstituted in methanol, was analyzed by reversed-phase liquid chromatography with triple-quadrupole tandem mass spectrometry. A central composite design multivariate method was used to optimize the interrelated parameters affecting DLLME efficiency. The absence of any matrix effect in the samples allowed them to be quantified against aqueous standards. The optimized procedure was validated by recovery studies, which provided values in the 82-123% range. The detection limits varied between 0.2 and 5.7 ng L, depending on the analyte, and the intraday precision values were in the 0.1-7.5% range in terms of relative standard deviation. Ten water samples taken from different points of the Mar Menor lagoon were analyzed and were found to be free of the studied toxins.
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http://dx.doi.org/10.3390/toxins13010057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7828625PMC
January 2021

Development of a new methodology for the determination of N-nitrosamines impurities in ranitidine pharmaceuticals using microextraction and gas chromatography-mass spectrometry.

Talanta 2021 Feb 15;223(Pt 2):121659. Epub 2020 Sep 15.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100, Murcia, Spain. Electronic address:

Ranitidine drug products were recently recalled because they contained carcinogenic nitrosamines (NAs), such as N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA). This episode emphasises the importance of developing analytical methods to determine NAs in this type of product. This study describes the development and validation of an analytical method for the determination of nine NAs (NDMA, N-nitrosomethylethylamine (NEMA), NDEA, N-nitrosopyrrolidine (NPYR), N-nitrosomorpholine (NMOR) N-nitrosodi-n-propylamine (NDPA) N-nitrosopiperidine (NPIP), N-nitrosodi-n-butylamine (NDBA) and N-nitrosodiphenylamine (NDPhA)) in ranitidine drug samples using a combination of microextraction and gas chromatography-mass spectrometry. The procedure involved the dissolution of 1 g of sample in 10 mL of water. For the dispersive liquid-liquid microextraction, 0.5 g of NaCl was added to this aqueous solution, followed by a mixture containing 0.5 mL methanol as dispersant and 150 μL chloroform as extractant solvent. The recovered organic phase was injected into the GC-MS system and a 20 min oven programme was applied. Quantification limits were in the 0.21-21 ng g range, corresponding the lower limit to NDPhA and the higher to NDMA. Relative standard deviations lower than 12% were achieved in all cases, which indicates the adequate precision of the method. Seven pharmaceutical products containing two different amounts of ranitidine (150 and 300 mg) were analysed. None of the samples contained NEMA, NDEA, NPYR, NMOR, NDPA or NPIP, while NDMA, NDBA and NDPhA were found in three products.
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http://dx.doi.org/10.1016/j.talanta.2020.121659DOI Listing
February 2021

A rapid dispersive liquid-liquid microextraction of antimicrobial onion organosulfur compounds in animal feed coupled to gas chromatography-mass spectrometry.

Anal Methods 2020 06;12(21):2668-2673

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain.

A rapid analytical procedure is proposed for determining two antimicrobial onion organosulfur compounds, propyl disulfide (PDS) and propyl propane thiosulfonate (PTSO), in animal feed. The use of PTSO as a natural ingredient in animal feed is allowed due to its antimicrobial activity against pathogenic organisms. Two analytical methodologies using gas chromatography coupled to mass spectrometry (GC-MS) are compared. After the extraction of the compounds from animal feed with acetonitrile, dispersive solid phase extraction (DSPE) as a cleaning stage with C18, or dispersive liquid-liquid microextraction (DLLME), using 100 μL of CHCl3, was tried. Both the methods were validated using a pig feed sample and the best results were achieved by DLLME. This technique provided cleaner extracts, five-times greater linear ranges and lower detection limits than simple cleaning due to the enrichment factor achieved. The relative standard deviation decreased from 22% with DSPE to 13% with DLLME. The usefulness of the DLLME-GC-MS methodology was tested by analysing 10 different samples of chicken, calf, hen, cow and fish feed. The concentrations of PDS were in the 0.1-1.7 μg g-1 range and those of PTSO were between 0.09 and 2.1 μg g-1.
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http://dx.doi.org/10.1039/d0ay00632gDOI Listing
June 2020

Targeted and untargeted gas chromatography-mass spectrometry analysis of honey samples for determination of migrants from plastic packages.

Food Chem 2021 Jan 10;334:127547. Epub 2020 Jul 10.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain. Electronic address:

Plastic food packages usually contain additives which may migrate from the package into the food and then be ingested by the consumer, representing a risk for their health. In this study, targeted and untargeted analysis by gas chromatography-mass spectrometry (GC-MS) is proposed to monitor any contaminants of this type in honey. The application of dispersive liquid-liquid microextraction (DLLME) as a preconcentration technique allowed very low detection limits to be reached for all the substances. Fifteen target compounds, including styrene, phthalates, fatty acids, alkylphenols and bisphenol A, were quantified. Untargeted analyses were also carried out, allowing other migrants in the honey samples to be identified, such as two phthalates, four acids, three esters, one aldehyde, one hydrocarbon and two alkyl phenol compounds. The proposed method was seen to be a useful approach for the quantification and identification of potential migrants from plastics in challenging samples such as honey.
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http://dx.doi.org/10.1016/j.foodchem.2020.127547DOI Listing
January 2021

Occurrence of Organochlorine Pesticides in Human Tissues Assessed Using a Microextraction Procedure and Gas Chromatography-Mass Spectrometry.

J Anal Toxicol 2021 Feb;45(1):84-92

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain.

This work focuses on the development, validation and application of an analytical method for the determination of twenty organochlorine pesticides (OCPs) in human tissues using salting-out liquid-liquid extraction and dispersive liquid-liquid microextraction for sample preparation and gas chromatography-mass spectrometry to analyze the obtained extracts. Measurement of the concentration levels of these toxics in tissues can be used to assess the risk of the population to exposure. The linearity of the proposed method was verified in the 10-1,000 ng/g range. The sensitivity was evaluated calculating the limits of detection (LODs) for 20 OCPs (α-, β-, γ- and δ-hexachlorocyclohexane (HCH), α- and β-endosulfan, endosulfan sulfate, aldrin, dieldrin, endrin, endrin ketone, endrin aldehyde, α- and γ-chlordane, 4,4'-dichlorodiphenyltrichloroethane, 4,4'-dichlorodiphenyldichloroethylene (DDE), 4,4'-dichlorodiphenyldichloroethane, heptachlor, heptachlor epoxide and methoxychlor), most of them being found between 1.0 and 16 ng/g. The intra- and interday precisions were <12% for relative standard deviation values. The accuracy of the method was evaluated by recovery studies, which gave recovery percentages in the 85-109% range. Seven different tissues (liver, kidney, heart, spleen, lung, brain and abdominal fat) from eight autopsies were analyzed, and only three cases were seen to have β-HCH and 4,4'-DDE in abdominal fat, while 4,4'-DDE was also detected in the heart of one case. The rest of the samples were free of the studied OCPs at least above the corresponding LODs.
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http://dx.doi.org/10.1093/jat/bkaa036DOI Listing
February 2021

Determination of amphenicol antibiotics and their glucuronide metabolites in urine samples using liquid chromatography with quadrupole time-of-flight mass spectrometry.

J Chromatogr B Analyt Technol Biomed Life Sci 2020 Jun 18;1146:122122. Epub 2020 Apr 18.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain. Electronic address:

A rapid procedure for the determination of amphenicol antibiotics in human urine by liquid chromatography with quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) is proposed. The presence of thiamphenicol (TAP), florfenicol (FF) and chloramphenicol (CAP) in the human body can be attributed to their administration to treat certain diseases or by eating food of animal origin. The TAP, FF and CAP excreted in urine is mainly in the form of glucuronide conjugates, although their free forms may also be excreted to a lesser extent. In the procedure described, the enzymatic hydrolysis of amphenicol glucuronide forms in urine was carried out using β-glucuronidase and sulfatase at pH 5 (37 °C, overnight) in order to discriminate the free and conjugated forms. Then, amphenicol antibiotics were submitted to dispersive liquid-liquid microextraction (DLLME) for preconcentration. All the parameters affecting DLLME efficiency were optimized, and the following conditions were selected: 0.9 g NaCl in 10 mL of urine, to which 1.2 mL methanol (as dispersant solvent) and 1 mL of 4-methyl-2-pentanone (as extractant solvent) were added. The absence of a matrix effect allowed quantification of the samples against aqueous standards. Detection limits were 29, 6 and 3 pg mL for TAP, FF and CAP, respectively. Relative standard deviations were calculated to evaluate the intra- and inter-day precision and values lower than 10% were obtained in all cases. The trueness of the method was tested through recovery studies, obtaining satisfactory values (83-104%). Ten urine samples obtained from volunteers were analysed and all of them were free of the studied antibiotics.
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http://dx.doi.org/10.1016/j.jchromb.2020.122122DOI Listing
June 2020

Dispersive Solid-Phase Extraction using Magnetic Carbon Nanotube Composite for the Determination of Emergent Mycotoxins in Urine Samples.

Toxins (Basel) 2020 01 15;12(1). Epub 2020 Jan 15.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain.

Dispersive magnetic solid-phase extraction (DMSPE) has received growing attention for sample treatment preconcentration prior to the separation of analytes due to its many advantages. In the present work, the potential of DMSPE for the determination of emergent mycotoxins (enniatins A, A1, B and B1, and beauvericin) is investigated for the first time. Different magnetic nanoparticles were tested and a magnetic multiwalled carbon nanotube ([email protected]) composite was selected for the extraction and preconcentration of the five target mycotoxins in human urine samples before their analysis by ultrahigh performance liquid chromatography coupled to high resolution mass spectrometry (UHPLC-HRMS). The nanocomposite was characterized by energy dispersive X-ray spectrometry, scanning electron microscopy, Fourier transform infrared spectrophotometry, and X-ray diffraction. Several parameters affecting the adsorption and desorption of DMSPE steps were optimized and the method was fully validated. Due to a matrix effect, matrix-matched calibration curves were necessary to carry out quantification. In this way, limits of quantification of between 0.04 and 0.1 μg/L, relative standard deviation values lower than 12% and recoveries between 89.3% and 98.9% were obtained. Finally, a study of the reuse of the [email protected] composite was carried out, confirming that it can be reused at least four times.
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http://dx.doi.org/10.3390/toxins12010051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7020456PMC
January 2020

Determination of Cyanotoxins and Phycotoxins in Seawater and Algae-Based Food Supplements Using Ionic Liquids and Liquid Chromatography with Time-Of-Flight Mass Spectrometry.

Toxins (Basel) 2019 10 22;11(10). Epub 2019 Oct 22.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain.

An analytical procedure is proposed for determining three cyanotoxins (microcystin RR, microcystin LR, and nodularin) and two phycotoxins (domoic and okadaic acids) in seawater and algae-based food supplements. The toxins were first isolated by a salting out liquid extraction procedure. Since the concentration expected in the samples was very low, a dispersive liquid-liquid microextraction procedure was included for preconcentration. The ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate (80 mg) was used as green extractant solvent and acetonitrile as disperser solvent (0.5 mL) for a 10 mL sample volume at pH 1.5, following the principles of green analytical chemistry. Liquid chromatography with electrospray ionization and quadrupole time of flight-mass spectrometry (LC-Q-TOF-MS) was used. The selectivity of the detection system, based on accurate mass measurements, allowed the toxins to be unequivocally identified. Mass spectra for quadrupole time of flight-mass spectrometry (Q-TOF-MS) and Q-TOF-MS/MS were recorded in the positive ion mode and quantification was based on the protonated molecule. Retention times ranged between 6.2 and 17.9 min using a mobile phase composed by a mixture of methanol and formic acid (0.1%). None of the target toxins were detected in any of the seawater samples analyzed, above their corresponding detection limits. However, microcystin LR was detected in the blue green alga sample.
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http://dx.doi.org/10.3390/toxins11100610DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6832300PMC
October 2019

Dual stir bar sorptive extraction coupled to thermal desorption-gas chromatography-mass spectrometry for the determination of endocrine disruptors in human tissues.

Talanta 2020 Jan 6;207:120331. Epub 2019 Sep 6.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100, Murcia, Spain. Electronic address:

The validation of a procedure for the determination of six alkylphenols (APs), 4-tert-butylphenol, 4-pentylphenol, 4-tert-octylphenol, 4-hexylphenol, 4-octylphenol and 4-nonylphenol, and three bisphenols (BPs), bisphenol A, bisphenol F and bisphenol Z, in seven human organs and tissues (kidney, liver, heart, lung, spleen, brain and abdominal fat) obtained from eight autopsies is presented. Previously ground samples were treated by salt-assisted liquid-liquid extraction (SALLE) for isolation of the analytes and then pre-concentrated using dual stir bar sorptive extraction (SBSE), allowing two different extraction conditions for the same sample. Finally, thermal desorption was used as the injector system in combination with gas chromatography coupled to mass spectrometry (GC-MS). To determine BPs, derivatization using acetic anhydride was required, although this step was not necessary for the APs. Two parallel extractions of the contaminants with the stir bars were performed, followed by thermal desorption and chromatographic analysis. The procedure provided quantification limits between 0.050 and 4.0 ng g for APs and from 0.26 to 2.6 ng g for BPs. Repeatability and reproducibility values were lower than 15% in all cases. The accuracy of the procedure was established by a recovery study, which provided values in the 85.8-115% range for APs and 83.6-120% for BPs. Samples were analyzed with the proposed methodology and data were processed by ANOVA tests to study the behaviour and bioaccumulation of these compounds in human tissues or organs. In addition, discriminant analysis detected age- and sex-dependent differences in bioaccumulation.
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http://dx.doi.org/10.1016/j.talanta.2019.120331DOI Listing
January 2020

Untargeted headspace gas chromatography - Ion mobility spectrometry analysis for detection of adulterated honey.

Talanta 2019 Dec 5;205:120123. Epub 2019 Jul 5.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100, Murcia, Spain. Electronic address:

The recognized properties of honey together with its price have, almost inevitably, led to economically motivated adulteration. In this work, headspace gas chromatography coupled to ion mobility spectrometry (HS-GC-IMS) is proposed for the differentiation of honey according to its purity and the level of adulteration by sugar cane or corn syrups. An easy and rapid sample treatment, consisting of incubating 1 g of honey at 100 °C for 15 min and then injecting 750 μL of the sample headspace into the GC-IMS system, is proposed. A 3-dimensional data map is obtained in 32 min. The proposed method was used for the analysis of 198 honey samples (56 pure honeys of different botanical origins, 71 honeys adulterated with sugar cane syrup and 71 adulterated with corn syrup). The influence of the adulterant on variations in the honey sample spectrum was studied. In order to obtain chemometric models for the detection of adulterated honey samples, the data obtained by HS-GC-IMS were processed selecting the significant markers of the spectrum fingerprint. OPLS-DA models were constructed using 80% of the samples, and the remaining 20% were used for method validation. The differentiation between pure and adulterated honeys had a validation success of 97.4%, and the assessment of adulterant content was obtained with a 93.8% validation success rate for both adulterant agents assayed. Nine commercial honey samples were analysed using the proposed methodology, and seven of them were classified as adulterated.
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http://dx.doi.org/10.1016/j.talanta.2019.120123DOI Listing
December 2019

Bioaccumulation of Polycyclic Aromatic Hydrocarbons for Forensic Assessment Using Gas Chromatography-Mass Spectrometry.

Chem Res Toxicol 2019 08 24;32(8):1680-1688. Epub 2019 Jul 24.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum" , University of Murcia , E-30100 Murcia , Spain.

Polycyclic aromatic hydrocarbons (PAHs) are considered xenobiotics of a potentially carcinogenic nature, being accumulated in the fatty tissue of the body. The objective of this work was the development and validation of a new analytical method to check the bioaccumulation of these toxic compounds in human organs obtained from autopsies. The contaminants were first isolated from the tissues by salt-assisted liquid-liquid extraction in acetonitrile. Because of the low concentrations of these compounds in the human body, a dispersive liquid-liquid microextraction procedure was included. The preconcentrated samples were analyzed by gas chromatography-mass spectrometry to identify the compounds. Principal component analysis was applied to show the natural clustering of forensic samples and orthogonal partial least-squares discriminant analysis to develop a multivariate regression method, which permitted the classification of samples. The quantification limits for the 13 PAHs (acenaphthylene, fluorene, phenanthrene, anthracene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, benzo(g,h,i)perylene, and indeno(1,2,3-cd)pyrene) analyzed were in the 0.06-0.44 ng g range, depending on the compound, while the mean intraday relative standard deviation of about 7% demonstrated the high precision of the method. Linearity was verified in the 0.5-200 ng g range, and the enrichment factors were between 55 and 122. The results provided by the analysis of seven different human organs (brain, liver, kidney, lung, heart, spleen, and abdominal fat) from eight autopsies confirmed the PAH-bioaccumulation capacity of human body, fat showing the highest degree of bioaccumulation. The present work is the first study on PAH contamination in different organs obtained from autopsies, being PAH detected in most human samples at values ranged from 0 to 19 ng g.
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http://dx.doi.org/10.1021/acs.chemrestox.9b00213DOI Listing
August 2019

Microwave Assisted Cloud Point Extraction for the Determination of Vitamin K Homologues in Vegetables by Liquid Chromatography with Tandem Mass Spectrometry.

J Agric Food Chem 2019 Jun 29;67(23):6658-6664. Epub 2019 May 29.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia , E-30100 Murcia , Spain.

Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) with a triple quadrupole (QqQ) is proposed for determining the vitamin K homologues, phylloquinone (PK), menaquinone-4 (MK) and menadione (MD), in vegetables. The analytes were isolated from the samples (1-1.5 g) by ultrasound assisted extraction using acetonitrile (2 mL), and the liquids were submitted to microwave assisted cloud point extraction with Triton X-45. The enrichment factors were between 20 and 50, depending on the vitamin homologue in question. The analytes were determined by LC-ESI-QqQ-MS/MS in the multiple reaction monitoring (MRM) mode, providing unequivocal identification and quantification, with limits of detection of 0.8, 1.0, and 16 ng/g for MK, PK, and MD, respectively. Recovery assays for samples spiked at two concentration levels, between 40 and 600 ng/g depending on the compound, provided recoveries in the 90-114% range. Only PK was detected in the samples analyzed, at concentrations in the 90-2350 ng/g range.
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http://dx.doi.org/10.1021/acs.jafc.9b01617DOI Listing
June 2019

Determination of nitrophenols in environmental samples using stir bar sorptive extraction coupled to thermal desorption gas chromatography-mass spectrometry.

Talanta 2018 Nov 20;189:543-549. Epub 2018 Jul 20.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain. Electronic address:

This paper presents a procedure for the determination of seven nitrophenols (NPs) in water and soil samples using stir bar sorptive extraction (SBSE) coupled to gas chromatography with mass spectrometry (GC-MS) by means of a thermal desorption unit (TDU). Microwave assisted extraction (MAE) is proposed to release the NPs from the soil matrices into an aqueous phase, prior to their acetylation. The different variables affecting the preconcentration efficiency of SBSE, during both the adsorption and the thermal desorption steps, are studied. As regards the analytical characteristics of the method, the accuracy was measured through recovery studies, recovery percentages in all cases being in the 79-120% range, as well as by analyzing a certified reference material. The precision was evaluated in terms of relative standard deviation, which provided values lower than 15% for both repeatability and reproducibility. The limits of detection were between 0.001 and 0.031 µg L for water and 0.020-0.107 ng g for soil samples. When environmental samples of different origins were analyzed, contents in the 0.01-1.0 µg L and 0.7-40 ng g ranges were obtained for waters and soils, respectively.
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http://dx.doi.org/10.1016/j.talanta.2018.07.043DOI Listing
November 2018

Magnetic carbon nanotube composite for the preconcentration of parabens from water and urine samples using dispersive solid phase extraction.

J Chromatogr A 2018 Aug 10;1564:102-109. Epub 2018 Jun 10.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain. Electronic address:

This study describes the use of a magnetic multi-walled carbon nanotube composite for the preconcentration of nine parabens (methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, phenyl and benzylparaben) from water and urine samples after in situ acetylation. The enriched extracts were obtained by dispersive magnetic solid phase extraction (DMSPE) and analysed by gas chromatography with mass spectrometry (GC-MS). Several parameters affecting the adsorption (extraction time, magnetic material mass and ionic strength) and desorption (desorption solvent nature and volume, and desorption time) DMSPE steps were investigated. Matrix-matched calibration was recommended for quantification of the samples. Linearities in the 0.5-150 ng mL range were obtained, depending on the compound. Under the optimal experimental conditions, the limits of detection ranged between 0.03 and 2.0 ng mL, depending on the sample matrix and the paraben congener. None of the samples analysed contained the above mentioned parabens. The method was validated with two water samples (harbour and wastewater treatment plant) and two urine samples spiked at two concentration levels. Recoveries in the 81-119% range were obtained.
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http://dx.doi.org/10.1016/j.chroma.2018.06.025DOI Listing
August 2018

Magnetic solid-phase extraction or dispersive liquid-liquid microextraction for pyrethroid determination in environmental samples.

J Sep Sci 2018 Jun 2;41(12):2565-2575. Epub 2018 May 2.

Faculty of Chemistry, Department of Analytical Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, Murcia, Spain.

The determination of 15 pyrethroids in soil and water samples was carried out by gas chromatography with mass spectrometry. Compounds were extracted from the soil samples (4 g) using solid-liquid extraction and then salting-out assisted liquid-liquid extraction. The acetonitrile phase obtained (0.8 mL) was used as a dispersant solvent, to which 75 μL of chloroform was added as an extractant solvent, submitting the mixture to dispersive liquid-liquid microextraction. For the analysis of water samples (40 mL), magnetic solid-phase extraction was performed using nanocomposites of magnetic nanoparticles and multiwalled carbon nanotubes as sorbent material (10 mg). The mixture was shaken for 45 min at room temperature before separation with a magnet and desorption with 3 mL of acetone using ultrasounds for 5 min. The solvent was evaporated and reconstituted with 100 μL acetonitrile before injection. Matrix-matched calibration is recommended for quantification of soil samples, while water samples can be quantified by standards calibration. The limits of detection were in the range of 0.03-0.5 ng/g (soil) and 0.09-0.24 ng/mL (water), depending on the analyte. The analyzed environmental samples did not contain the studied pyrethroids, at least above the corresponding limits of detection.
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http://dx.doi.org/10.1002/jssc.201800109DOI Listing
June 2018

Determination of synthetic phosphodiesterase-5 inhibitors by LC-MS in waters and human urine submitted to dispersive liquid-liquid microextraction.

Talanta 2017 Nov 29;174:638-644. Epub 2017 Jun 29.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, E-30100 Murcia, Spain.

High-performance liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS) with a triple quadrupole is proposed for determining the synthetic phosphodiesterase-5 inhibitors, sildenafil, tadalafil and vardenafil, and the active metabolite N-desmethyl sildenafil. The method was successfully applied to the analysis of waters of different origins and human urine samples. Dispersive liquid-liquid microextraction (DLLME) was applied in the classical way for water analysis, whereas a previous extraction into an organic solvent was necessary for urine samples, the acetonitrile extract being used as dispersant solvent in the DLLME step. The analytes were determined by LC-ESI-MS in the multiple reaction monitoring mode. Detection limits were in the 5-50 and 15-250ngL ranges for water and urine samples, respectively. The repeatability was calculated using the relative standard deviation, obtaining values of between 3.6% and 10.1%. The enrichment factors were between 75 and 81. Accuracy of the procedure was calculated through recovery assays and average recoveries ± SD (n = 48) of 93.6 ± 3.5 and 91.1 ± 3.5 were obtained for water and urine samples, respectively. None of the samples analyzed contained the target compounds, at least above the corresponding detection limits.
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http://dx.doi.org/10.1016/j.talanta.2017.06.076DOI Listing
November 2017

Combination of solvent extractants for dispersive liquid-liquid microextraction of fungicides from water and fruit samples by liquid chromatography with tandem mass spectrometry.

Food Chem 2017 Oct 19;233:69-76. Epub 2017 Apr 19.

Equipo de Calidad Alimentaria, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), C/ Mayor s/n, La Alberca, 30150 Murcia, Spain. Electronic address:

A multiresidue method was developed to determine twenty-five fungicides belonging to three different chemical families, oxazoles, strobilurins and triazoles, in water and fruit samples, using dispersive liquid-liquid microextraction (DLLME) and liquid chromatography/tandem mass spectrometry (LC-MS). Solid-liquid extraction with acetonitrile was used for the analysis in fruits, the extract being used as dispersant solvent in DLLME. Since some of the analytes showed high affinity for chloroform and the others were more efficiently extracted with undecanol, a mixture of both solvents was used as extractant in DLLME. After evaporation of CHCl, the enriched phase was analyzed. Enrichment factors in the 23-119 and 12-60 ranges were obtained for waters and fruits, respectively. The approach was most sensitive for metominostrobin with limits of quantification of 1ngL and 5ngkg in waters and fruits, respectively, while a similar sensitivity was attained for tebuconazole in fruits. Recoveries of the fungicides varied between 86 and 116%.
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http://dx.doi.org/10.1016/j.foodchem.2017.04.094DOI Listing
October 2017

Gas chromatography with mass spectrometry for the determination of phthalates preconcentrated by microextraction based on an ionic liquid.

J Sep Sci 2017 Mar 14;40(6):1310-1317. Epub 2017 Feb 14.

Faculty of Chemistry, Department of Analytical Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum," University of Murcia, Murcia, Spain.

A new procedure is proposed for the analysis of migration test solutions obtained from plastic bottles used in the packaging of edible oils. Ultrasound-assisted emulsification microextraction with ionic liquids was applied for the preconcentration of six phthalate esters: dimethylphthalate, diethylphthalate, di-n-butylphthalate, n-butylbenzylphthalate, di-2-ethylhexylphthalate, and di-n-octylphthalate. The enriched ionic liquid was directly analyzed by gas chromatography and mass spectrometry using direct insert microvial thermal desorption. The different factors affecting the microextraction efficiency, such as volume of the extracting phase (30 μL of the ionic liquid) and ultrasound application time (25 s), and the thermal desorption step, such as desorption temperature and time, and gas flow rate, were studied. Under the selected conditions, detection limits for the analytes were in the 0.012-0.18 μg/L range, while recovery assays provided values ranging from 80 to 112%. The use of butyl benzoate as internal standard increased the reproducibility of the analytical procedure. When the release of the six phthalate esters from the tested plastic bottles to liquid simulants was monitored using the optimized procedure, analyte concentrations of between 1.0 and 273 μg/L were detected.
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http://dx.doi.org/10.1002/jssc.201601173DOI Listing
March 2017

Glyoxal and methylglyoxal determination in urine by surfactant-assisted dispersive liquid-liquid microextraction and LC.

Bioanalysis 2017 Feb 19;9(4):369-379. Epub 2017 Jan 19.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia, E-30100 Murcia, Spain.

Aim: Two important markers of oxidative stress, glyoxal and methylglyoxal, are preconcentrated from human urine by surfactant-assisted dispersive liquid-liquid microextraction and separated by LC-fluorescence.

Methods/results: Derivatization was carried out overnight with 0.8 mM 2,3-diaminonaphthalene at 4°C. For surfactant-assisted dispersive liquid-liquid microextraction, 500 µl buffer solution (pH 10.5) and 25 µl 0.03 M Triton X-114 were added to 2.5 ml of the sample and the mixture was made up to 10 ml before the rapid injection of 75 µl 1-undecanol (extractant solvent) and 0.5 ml ethanol (dispersant solvent).

Conclusion: The method can be applied to analyze glyoxal and methylglyoxal in urine with LOD of 13 and 16 ng/l, respectively, and recoveries in the 88-103% range.
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http://dx.doi.org/10.4155/bio-2016-0217DOI Listing
February 2017

Magnetic solid phase extraction with CoFeO/oleic acid nanoparticles coupled to gas chromatography-mass spectrometry for the determination of alkylphenols in baby foods.

Food Chem 2017 Apr 11;221:76-81. Epub 2016 Oct 11.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain. Electronic address:

Magnetic solid phase extraction (MSPE) with cobalt ferrite nanoparticles coated with oleic acid is described for the determination of alkylphenols (APs), 4-tert-butylphenol (TBP), 4-pentylphenol (PP), 4-hexylphenol (HP), 4-tert-octylphenol (TOP), 4-n-octylphenol (OP) and 4-nonylphenol (NP) in baby foods using gas chromatography with mass spectrometry (GC-MS). Prior to MSPE, the sample was treated with trichloroacetic acid, and the APs derivatized with acetic anhydride. Parameters affecting the extraction efficiency: amount of magnetic nanoparticles, extraction time and desorption conditions, were optimized. The enriched phase obtained was evaporated to dryness and the residue reconstituted in 50μL of methanol, 1μL of which was injected into the GC-MS. Samples were quantified applying matrix-matched calibration and using 2-chloro-5-bromoanisole as surrogate standard. The analysis of 0.5g of sample provided detection limits in the 0.4-1.7ngg range. Some samples contained APs at levels of between 3ngg for HP and 122ngg for TOP.
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http://dx.doi.org/10.1016/j.foodchem.2016.10.035DOI Listing
April 2017

A study of the influence on diabetes of free and conjugated bisphenol A concentrations in urine: Development of a simple microextraction procedure using gas chromatography-mass spectrometry.

J Pharm Biomed Anal 2016 Sep 28;129:458-465. Epub 2016 Jul 28.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain. Electronic address:

The association between bisphenol A (BPA) exposure and adult health status is examined by measuring the urinary BPA concentration using a miniaturized technique based on dispersive liquid-liquid microextraction (DLLME) in combination with gas chromatography-mass spectrometry (GC-MS). Both the free bioactive and the glucuronide conjugated forms of BPA were measured, the glucuronide form usually being predominant. The main analogs of BPA, including bisphenol Z (BPZ), bisphenol F (BPF) and biphenol (BP) were also determined. Several parameters affecting enzymatic hydrolysis, derivatization by in-situ acetylation and the DLLME stages were carefully optimized by means of multivariate designs. DLLME parameters were 2mL urine, 1mL acetone and 100μL chloroform, and hydrolysis was performed using β-glucuronidase and sulfatase at pH 5. No matrix effect was observed and quantification was carried out by aqueous calibration with a surrogate standard. Detection limits were in the range 0.01-0.04ngmL(-1). The intraday and interday precisions were lower than 11% in terms of relative standard deviation. Satisfactory values for all compounds were obtained in recovery studies (92-117%) at two concentration levels. Other bisphenols (BPF, BPZ and BP) were not detected in the urine samples, while BPA was the only bisphenol detected in the free form (creatinine adjusted) at concentration levels ranging from the detection limit to 15.9ngg(-1), and total BPA was detected at concentrations ranging from 0.46 to 24.5ngg(-1) levels. A comparison of the BPA content for both groups of patients revealed that slightly higher mean values were obtained for both free BPA and total BPA for diabetic patients, than for non-diabetic patients. However, a statistical comparison of the contents of BPA revealed that there were no significant differences. The procedure was validated using a certified reference material.
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http://dx.doi.org/10.1016/j.jpba.2016.07.042DOI Listing
September 2016

Gas chromatography with mass spectrometry for the quantification of ethylene glycol ethers in different household cleaning products.

J Sep Sci 2016 Jun 30;39(12):2292-9. Epub 2016 May 30.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, Murcia, Spain.

A rapid and simple procedure is reported for the determination of six ethylene glycol ethers in cleaning products and detergents using gas chromatography with mass spectrometry. The analytes were extracted from 2.0 g samples in acetonitrile (3 mL) and the extract was submitted to a clean-up step by QuEChERS method, using a mixture containing 0.3 g magnesium sulfate, 0.15 g primary/secondary amine, and 0.05 g C18 . The clean acetonitrile extract (1 μL) was injected into the chromatographic system. No matrix effect was observed, so the quantification of the samples was carried out against external standards. Detection limits were in the range 3.0-27 ng/g for the six ethylene glycol ethers. The recoveries obtained, using the optimized procedure, were in the 89.4-118% range, with relative standard deviations lower than 14%. Twenty-three different household cleaning products, including glass cleaner, degreaser, floor, softeners, and clothes and dishwashing detergents, were analyzed. Large interindividual variations were observed between samples and compounds.
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http://dx.doi.org/10.1002/jssc.201600180DOI Listing
June 2016

Use of oleic-acid functionalized nanoparticles for the magnetic solid-phase microextraction of alkylphenols in fruit juices using liquid chromatography-tandem mass spectrometry.

Talanta 2016 May 21;151:217-223. Epub 2016 Jan 21.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain. Electronic address:

Magnetic nanoparticles of cobalt ferrite with oleic acid as the surfactant (CoFe2O4/oleic acid) were used as sorbent material for the determination of alkylphenols in fruit juices. High sensitivity and specificity were achieved by liquid chromatography and detection using both diode-array (DAD) and electrospray-ion trap-tandem mass spectrometry (ESI-IT-MS/MS) in the selected reaction monitoring (SRM) mode of the negative fragment ions for alkylphenols (APs) and in positive mode for ethoxylate APs (APEOs). The optimized conditions for the different variables influencing the magnetic separation procedure were: mass of magnetic nanoparticles, 50mg, juice volume, 10mL diluted to 25mL with water, pH 6, stirring for 10min at room temperature, separation with an external neodymium magnet, desorption with 3mL of methanol and orbital shaking for 5min. The enriched organic phase was evaporated and reconstituted with 100µL acetonitrile before injecting 30µL into a liquid chromatograph with a mobile phase composed of acetonitrile/0.1% (v/v) formic acid under gradient elution. Quantification limits were in the range 3.6 to 125ngmL(-1). The recoveries obtained were in the 91-119% range, with RSDs lower than 14%. The ESI-MS/MS spectra permitted the correct identification of both APs and APEOs in the fruit juice samples.
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http://dx.doi.org/10.1016/j.talanta.2016.01.039DOI Listing
May 2016

Determination of spirocyclic tetronic/tetramic acid derivatives and neonicotinoid insecticides in fruits and vegetables by liquid chromatography and mass spectrometry after dispersive liquid-liquid microextraction.

Food Chem 2016 Jul 1;202:389-95. Epub 2016 Feb 1.

Equipo de Calidad Alimentaria, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), C/ Mayor s/n, La Alberca, 30150 Murcia, Spain. Electronic address:

Dispersive liquid-liquid microextraction was used to preconcentrate three spirocyclic tetronic/tetramic acid derivatives (spirotetramat, spiromesifen and spirodiclofen) and five neonicotinoid (thiamethoxam, chlotianidin, imidacloprid, acetamiprid and thiacloprid) insecticides previously extracted from fruit and vegetable matrices with acetonitrile. The organic enriched phase was evaporated, reconstituted in 25μL acetonitrile and analyzed by reversed-phase liquid chromatography with tandem mass spectrometry using a triple quadrupole in selected reaction monitoring mode. Enrichment factors in the 15-100 range were obtained. A matrix effect was observed, the detection limits varying between 0.025 and 0.5ngg(-1), depending on the compound and the sample matrix. The developed method was applied to the analysis of 25 samples corresponding to five different fruit and vegetable matrices. Only thiamethoxam was detected in a lemon sample at a concentration close to the quantification limit, and spiromesifen and spirotetramat at concentrations between 11.6 and 54.5ngg(-1).
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http://dx.doi.org/10.1016/j.foodchem.2016.01.143DOI Listing
July 2016

Determination of synthetic phenolic antioxidants in edible oils using microvial insert large volume injection gas-chromatography.

Food Chem 2016 Jun 8;200:249-54. Epub 2016 Jan 8.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, E-30100 Murcia, Spain. Electronic address:

Three synthetic phenolic antioxidants, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ), were determined in different edible vegetable oil samples. The analyses were carried out by gas chromatography-mass spectrometry (GC-MS) using microvial insert large volume injection (LVI). Several parameters affecting this sample introduction step, such as temperatures, times and gas flows, were optimised. Quantification was carried out by the matrix-matched calibration method using carvacrol as internal standard, providing quantification limits between 0.08 and 0.10 ng g(-1), depending on the compound. The three phenolic compounds were detected in several of the samples, BHT being the most frequently found. Recovery assays for oil samples spiked at two concentration levels, 2.5 and 10 ng g(-1), provided recoveries in the 86-115% range.
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http://dx.doi.org/10.1016/j.foodchem.2016.01.026DOI Listing
June 2016

Improved sensitivity gas chromatography-mass spectrometry determination of parabens in waters using ionic liquids.

Talanta 2016 Jan 11;146:568-74. Epub 2015 Sep 11.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, E-30100 Murcia, Spain. Electronic address:

A new procedure for the introduction of ionic liquid samples in gas chromatography (GC) is proposed. This procedure, based on microvial insert thermal desorption, allows the direct analysis of the compounds preconcentrated by ionic liquid based liquid-liquid microextraction (IL-LLME) using the combination of a thermal desorption unit (TDU) and a programmed temperature vaporization injector (PTV). Two different IL-LLME methodologies, one based on the formation of a microdroplet emulsion by dispersive liquid-liquid microextraction (DLLME) and other through ultrasound-assisted emulsification microextraction (USAEME) were studied and evaluated. IL-DLLME proved advantageous and consequently, it was adopted for preconcentration purposes. This easy to apply approach was used for the determination of five parabens (methyl-, ethyl-, propyl-, butyl- and isobutyl paraben) in swimming pool waters, after in situ acetylation. The optimized conditions of TDU/PTV allowed the analytes contained in 20 µL of the enriched IL to be transferred to the capillary column. Quantification of the samples was carried out against aqueous standards, and quantification limits of between 4.3 and 8.1 ng L(-1) were obtained, depending on the compound. Concentrations of between 9 and 47 ng L(-1) for some analytes were obtained in the analysis of ten samples.
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http://dx.doi.org/10.1016/j.talanta.2015.09.022DOI Listing
January 2016

In situ ionic liquid dispersive liquid-liquid microextraction and direct microvial insert thermal desorption for gas chromatographic determination of bisphenol compounds.

Anal Bioanal Chem 2016 Jan 17;408(1):243-9. Epub 2015 Oct 17.

Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, 30100, Murcia, Spain.

A new procedure based on direct insert microvial thermal desorption injection allows the direct analysis of ionic liquid extracts by gas chromatography and mass spectrometry (GC-MS). For this purpose, an in situ ionic liquid dispersive liquid-liquid microextraction (in situ IL DLLME) has been developed for the quantification of bisphenol A (BPA), bisphenol Z (BPZ) and bisphenol F (BPF). Different parameters affecting the extraction efficiency of the microextraction technique and the thermal desorption step were studied. The optimized procedure, determining the analytes as acetyl derivatives, provided detection limits of 26, 18 and 19 ng L(-1) for BPA, BPZ and BPF, respectively. The release of the three analytes from plastic containers was monitored using this newly developed analytical method. Analysis of the migration test solutions for 15 different plastic containers in daily use identified the presence of the analytes at concentrations ranging between 0.07 and 37 μg L(-1) in six of the samples studied, BPA being the most commonly found and at higher concentrations than the other analytes.
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http://dx.doi.org/10.1007/s00216-015-9098-zDOI Listing
January 2016

Assessment of strobilurin fungicides' content in soya-based drinks by liquid micro-extraction and liquid chromatography with tandem mass spectrometry.

Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2015 14;32(12):2039-47. Epub 2015 Oct 14.

a Department of Analytical Chemistry, Faculty of Chemistry , Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia , Murcia , Spain.

Seven strobilurin fungicides were pre-concentrated from soya-based drinks using dispersive liquid-liquid micro-extraction (DLLME) with a prior protein precipitation step in acid medium. The enriched phase was analysed by liquid chromatography (LC) with dual detection, using diode array detection (DAD) and electrospray-ion trap tandem mass spectrometry (ESI-IT-MS/MS). After selecting 1-undecanol and methanol as the extractant and disperser solvents, respectively, for DLLME, the Taguchi experimental method, an orthogonal array design, was applied to select the optimal solvent volumes and salt concentration in the aqueous phase. The matrix effect was evaluated and quantification was carried out using external aqueous calibration for DAD and matrix-matched calibration method for MS/MS. Detection limits in the 4-130 and 0.8-4.5 ng g(-1) ranges were obtained for DAD and MS/MS, respectively. The DLLME-LC-DAD-MS method was applied to the analysis of 10 different samples, none of which was found to contain residues of the studied fungicides.
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http://dx.doi.org/10.1080/19440049.2015.1096966DOI Listing
September 2016
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