The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform

R Cela - One of the best experts on this subject based on the ideXlab platform.

  • determination of selected uv filters in indoor dust by matrix solid phase dispersion and gas chromatography tandem mass spectrometry
    Journal of Chromatography A, 2009
    Co-Authors: Noelia Negreira, I Rodriguez, E Rubi, R Cela
    Abstract:

    Abstract A simple, inexpensive sample preparation procedure, based on the matrix solid-phase dispersion (MSPD) technique, for the determination of six UV filters: 2-ethylhexyl salicylate (EHS), 3,3,5-trimethylcyclohexyl salicylate (Homosalate, HMS), 3-(4-methylbenzylidene) camphor (4-MBC), isoamyl-p-methoxycinnamate (IAMC), 2-ethylhexyl-p-methoxycinnamate (EHMC) and octocrylene (OCR), in dust from indoor environments is presented and the influence of several operational parameters on the extraction performance discussed. Under the final working conditions, sieved samples (0.5 g) were mixed with the same amount of anhydrous sodium sulphate and dispersed with 2 g of octadecyl bonded silica (C18) in a mortar with a pestle. This blend was transferred to a polypropylene solid-phase extraction cartridge containing 2 g of activated silica, as the clean-up co-sorbent. The cartridge was first rinsed with 5 mL of n-hexane and the analytes were then recovered with 4 mL of acetonitrile. This extract was adjusted to 1 mL, filtered and the compounds were determined by gas chromatography combined with tandem mass spectrometry (GC–MS/MS). Recoveries for samples spiked at two different concentrations ranged between 77% and 99%, and the limits of quantification (LOQs) of the method between 10 and 40 ng g−1. Analysis of settled dust from different indoor areas, including private flats, public buildings and vehicle cabins, showed that EHMC and OCR were ubiquitous in this matrix, with maximum concentrations of 15 and 41 μg g−1, respectively. Both UV filters were also quantified in dust reference material SRM 2585 for first time. EHS, 4-MBC and IAMC were detected in some of the analyzed samples, although at lower concentrations than EHMC and OCR.

  • sensitive determination of salicylate and benzophenone type uv filters in water samples using solid phase microextraction derivatization and gas chromatography tandem mass spectrometry
    Analytica Chimica Acta, 2009
    Co-Authors: Noelia Negreira, I Rodriguez, E Rubi, M Ramil, R Cela
    Abstract:

    Abstract A sensitive procedure for the determination of three UV filters: ethylhexyl salicylate (EHS), 3,3,5-trimethylcyclohexyl salicylate (Homosalate, HMS), 2-hydroxy-4-methoxybenzophenone (BP-3) and two related hydroxylated benzophenones (2,4-dihydroxybenzophenone, BP-1 and 2,2′-dihydroxy-4-methoxybenzophenone, BP-8) in water samples is presented. Analytes were first concentrated on the coating of a solid-phase microextraction (SPME) fibre, on-fibre silylated and then determined using gas chromatography combined with tandem mass spectrometry (GC–MS/MS). Factors affecting the performance of extraction and derivatization steps are thoroughly evaluated and their effects on the yield of the sample preparation discussed. Under final working conditions, a PDMS-DVB coated SPME fibre was exposed directly to 10 mL of water, adjusted at pH 3, for 30 min. After that, the fibre was placed in the headspace (HS) of a 1.5 mL vial containing 20 μL of N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA). On-fibre silylation of hydroxyl groups contained in the structure of target compounds was performed at 45 °C for 10 min. The whole sample preparation process was completed in 40 min, providing limits of quantification from 0.5 to 10 ng L −1 and acceptable precision (RSDs under 13%) for samples spiked at different concentrations. All compounds could be accurately determined in river and treated wastewater (relative recoveries from 89 to 115%) using standards in ultrapure water, whereas standard addition is recommended to quantify their levels in untreated wastewater. Analysis of wastewater revealed the systematic presence of BP-3 and BP-1 in raw samples with maximum concentrations close to 500 and 250 ng L −1 , respectively.

Hian Kee Lee - One of the best experts on this subject based on the ideXlab platform.

  • simultaneous determination of ultraviolet filters in aqueous samples by plunger in needle solid phase microextraction with graphene based sol gel coating as sorbent coupled with gas chromatography mass spectrometry
    Analytica Chimica Acta, 2012
    Co-Authors: Hong Zhang, Hian Kee Lee
    Abstract:

    A simple, sensitive and selective method for the simultaneous determination of five ultraviolet (UV) filters: benzophenone, octyl salicylate, Homosalate, 3-(4-methylbenzylidene) camphor, 2-hydroxy-4-methoxybenzophenone in aqueous samples was developed. The analytes were extracted by plunger-in-needle solid-phase microextraction with graphene as sorbent, then silylated on-fiber with N-methyl-N-(trimethylsilyl)trifluoroacetamide, and analyzed by gas chromatography-mass spectrometry. Factors affecting the performance of extraction and derivatization steps were thoroughly evaluated. For the optimization of extraction conditions, six relevant factors (parameters) were investigated, including sample pH, salt concentration, extraction time, extraction temperature, stirring speed and sampling mode. In the first stage, a two-level orthogonal array design OA(8) (2(7)) matrix was employed to study the effect of six factors. Based on the results of the first stage, three factors were selected for further optimization with a univariant approach during the second stage. Under the final optimized conditions, the method limits of detection for the five UV filters were determined to be in the range of 0.5 and 6.8 ng L(-1) (at a signal/noise ratio of 3) and the precision (% relative standard deviation, n=5) was 0.8-5.6% at a concentration level of 1 μg L(-1). The linearities for different analytes were 10-10,000 or 1-5000 ng L(-1). The coefficients of determination for the calibration curves were all greater than 0.994. Finally, the proposed method was successfully applied to the extraction and determination of the UV filters in river water samples.

  • determination of ultraviolet filters in water samples by vortex assisted dispersive liquid liquid microextraction followed by gas chromatography mass spectrometry
    Journal of Chromatography A, 2012
    Co-Authors: Yufeng Zhang, Hian Kee Lee
    Abstract:

    Abstract For the first time, a simple solvent microextraction method termed vortex-assisted liquid–liquid microextraction (VADLLME) coupled with gas chromatography–mass spectrometry (GC–MS) has been developed and used for the analysis of six benzophenone ultraviolet (UV) filters (i.e. benzhydrol, 2,4-dihydroxybenzophenone, benzophenone, 2-hydroxy-4-methoxybenzophenone, ethylhexyl salicylate and Homosalate) in water samples. The most favorable extraction variables in the VADLLME process were determined. In the extraction procedure, 40 μL of tetrachloroethene as extraction solvent were directly injected into a 15-mL centrifuge tube containing 10 mL of aqueous sample, adjusted to pH 4 for VADLLME. After VADLLME, the extract was evaporated under a gentle nitrogen gas stream and then reconstituted with N , O -bis-(trimethylsilyl)trifluoroacetamide (BSTFA), thus allowing the target analytes to be converted into their trimethylsilyl derivatives to optimize the GC–MS analysis. No centrifugation and disperser solvent were required in this microextraction procedure. Significantly, short extraction time and high extraction efficiency were achieved. This method opens up a potentially new horizon for on-site dispersive liquid–liquid microextraction. Under the optimum conditions, the proposed method provided good enrichment factors up to 310, with relative standard deviations ranging from 6.1 to 12.9%. The limits of quantification were in the range of 20–100 ng/L, depending on the analytes. The linearities were between 0.05 and 10 μg/L and 0.1 and 10 μg/L for different UV filters. Finally, the proposed method was successfully applied to the determination of UV filters from spiked genuine water samples and acceptable recoveries over the range of 71.0–120.0% were obtained.

Noelia Negreira - One of the best experts on this subject based on the ideXlab platform.

  • determination of selected uv filters in indoor dust by matrix solid phase dispersion and gas chromatography tandem mass spectrometry
    Journal of Chromatography A, 2009
    Co-Authors: Noelia Negreira, I Rodriguez, E Rubi, R Cela
    Abstract:

    Abstract A simple, inexpensive sample preparation procedure, based on the matrix solid-phase dispersion (MSPD) technique, for the determination of six UV filters: 2-ethylhexyl salicylate (EHS), 3,3,5-trimethylcyclohexyl salicylate (Homosalate, HMS), 3-(4-methylbenzylidene) camphor (4-MBC), isoamyl-p-methoxycinnamate (IAMC), 2-ethylhexyl-p-methoxycinnamate (EHMC) and octocrylene (OCR), in dust from indoor environments is presented and the influence of several operational parameters on the extraction performance discussed. Under the final working conditions, sieved samples (0.5 g) were mixed with the same amount of anhydrous sodium sulphate and dispersed with 2 g of octadecyl bonded silica (C18) in a mortar with a pestle. This blend was transferred to a polypropylene solid-phase extraction cartridge containing 2 g of activated silica, as the clean-up co-sorbent. The cartridge was first rinsed with 5 mL of n-hexane and the analytes were then recovered with 4 mL of acetonitrile. This extract was adjusted to 1 mL, filtered and the compounds were determined by gas chromatography combined with tandem mass spectrometry (GC–MS/MS). Recoveries for samples spiked at two different concentrations ranged between 77% and 99%, and the limits of quantification (LOQs) of the method between 10 and 40 ng g−1. Analysis of settled dust from different indoor areas, including private flats, public buildings and vehicle cabins, showed that EHMC and OCR were ubiquitous in this matrix, with maximum concentrations of 15 and 41 μg g−1, respectively. Both UV filters were also quantified in dust reference material SRM 2585 for first time. EHS, 4-MBC and IAMC were detected in some of the analyzed samples, although at lower concentrations than EHMC and OCR.

  • sensitive determination of salicylate and benzophenone type uv filters in water samples using solid phase microextraction derivatization and gas chromatography tandem mass spectrometry
    Analytica Chimica Acta, 2009
    Co-Authors: Noelia Negreira, I Rodriguez, E Rubi, M Ramil, R Cela
    Abstract:

    Abstract A sensitive procedure for the determination of three UV filters: ethylhexyl salicylate (EHS), 3,3,5-trimethylcyclohexyl salicylate (Homosalate, HMS), 2-hydroxy-4-methoxybenzophenone (BP-3) and two related hydroxylated benzophenones (2,4-dihydroxybenzophenone, BP-1 and 2,2′-dihydroxy-4-methoxybenzophenone, BP-8) in water samples is presented. Analytes were first concentrated on the coating of a solid-phase microextraction (SPME) fibre, on-fibre silylated and then determined using gas chromatography combined with tandem mass spectrometry (GC–MS/MS). Factors affecting the performance of extraction and derivatization steps are thoroughly evaluated and their effects on the yield of the sample preparation discussed. Under final working conditions, a PDMS-DVB coated SPME fibre was exposed directly to 10 mL of water, adjusted at pH 3, for 30 min. After that, the fibre was placed in the headspace (HS) of a 1.5 mL vial containing 20 μL of N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA). On-fibre silylation of hydroxyl groups contained in the structure of target compounds was performed at 45 °C for 10 min. The whole sample preparation process was completed in 40 min, providing limits of quantification from 0.5 to 10 ng L −1 and acceptable precision (RSDs under 13%) for samples spiked at different concentrations. All compounds could be accurately determined in river and treated wastewater (relative recoveries from 89 to 115%) using standards in ultrapure water, whereas standard addition is recommended to quantify their levels in untreated wastewater. Analysis of wastewater revealed the systematic presence of BP-3 and BP-1 in raw samples with maximum concentrations close to 500 and 250 ng L −1 , respectively.

Hong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • a fully automated analytical platform integrating water sampling miniscale liquid liquid extraction full evaporation dynamic headspace concentration gas chromatography mass spectrometry for the analysis of ultraviolet filters
    Analytica Chimica Acta, 2018
    Co-Authors: Christina Shu Min Liew, Xiao Li, Hong Zhang
    Abstract:

    Abstract A fully automated analytical platform that seamlessly integrates online water sampling-sample preparation-gas chromatography-mass spectrometry (GC-MS) was developed for ultraviolet (UV) filters in this work. The online water sampling system consisted of a conventional sample vial (slightly modified to have both inlet and outlet ports), two tubings and a peristaltic pump, which controlled the water flow into and out of the vial. The sample preparation segment consists of miniscale liquid-liquid extraction (msLLE), coupled to full evaporation dynamic headspace concentration (FEDHS) on a commercial dual-arm autosampler. The extract from the msLLE step was subjected to a derivatization step, before being passed through a Tenax TA sorbent tube at the FEDHS stage. UV filters were used as model compounds in this work due to their potential endocrine and developmental toxicities, including benzhydrol, 2-ethylhexyl salicylate, Homosalate, 2-hydroxy-4-methoxybenzophenone, 3-(4′-methylbenzylidene) camphor and benzophenone. The analytes (of which the first four underwent derivatization, by virtue of them possessing hydroxyl groups, but not the last two) were concentrated on the sorbent, and were thermally desorbed before being introduced to the GC-MS system for analysis. An orthogonal array design (OAD) strategy was employed to facilitate the optimization of the msLLE and derivatization factors while univariate optimization was performed for FEDHS. The optimized settings achieved low limits of detection (0.6–9.7 ng L −1 ) with good linearity (r 2  ≥ 0.9926), and satisfactory absolute extraction recoveries (62.0%–80.7%) were obtained. The fully automated online water sampling-extraction/concentration-detection approach was demonstrated by applying it to the analysis of swimming pool water. Relative recoveries of the analytes in the pool water ranged from 85.4% to 118.2%. The described procedure has the potential to be a fully automated online water sampling-msLLE-FEDHS-GC-MS platform for the purpose of conducting routine onsite water analysis.

  • simultaneous determination of ultraviolet filters in aqueous samples by plunger in needle solid phase microextraction with graphene based sol gel coating as sorbent coupled with gas chromatography mass spectrometry
    Analytica Chimica Acta, 2012
    Co-Authors: Hong Zhang, Hian Kee Lee
    Abstract:

    A simple, sensitive and selective method for the simultaneous determination of five ultraviolet (UV) filters: benzophenone, octyl salicylate, Homosalate, 3-(4-methylbenzylidene) camphor, 2-hydroxy-4-methoxybenzophenone in aqueous samples was developed. The analytes were extracted by plunger-in-needle solid-phase microextraction with graphene as sorbent, then silylated on-fiber with N-methyl-N-(trimethylsilyl)trifluoroacetamide, and analyzed by gas chromatography-mass spectrometry. Factors affecting the performance of extraction and derivatization steps were thoroughly evaluated. For the optimization of extraction conditions, six relevant factors (parameters) were investigated, including sample pH, salt concentration, extraction time, extraction temperature, stirring speed and sampling mode. In the first stage, a two-level orthogonal array design OA(8) (2(7)) matrix was employed to study the effect of six factors. Based on the results of the first stage, three factors were selected for further optimization with a univariant approach during the second stage. Under the final optimized conditions, the method limits of detection for the five UV filters were determined to be in the range of 0.5 and 6.8 ng L(-1) (at a signal/noise ratio of 3) and the precision (% relative standard deviation, n=5) was 0.8-5.6% at a concentration level of 1 μg L(-1). The linearities for different analytes were 10-10,000 or 1-5000 ng L(-1). The coefficients of determination for the calibration curves were all greater than 0.994. Finally, the proposed method was successfully applied to the extraction and determination of the UV filters in river water samples.

Margarita Kapsi - One of the best experts on this subject based on the ideXlab platform.

  • persistent and emerging pollutants assessment on aquaculture oysters crassostrea gigas from nw portuguese coast ria de aveiro
    Science of The Total Environment, 2019
    Co-Authors: J R Gadelha, Cristina A S Rocha, Carolina Camacho, Ethel Eljarrat, Andrea Peris, Yann Aminot, James W Readman, Vasiliki Boti, Christina I Nannou, Margarita Kapsi
    Abstract:

    The study aim was to determine a range of relevant persistent and emerging pollutants in oysters produced in an aquaculture facility located in an important production area, to assure their safety for human consumption. Pollutants, including 16 PAHs, 3 butyltins (BTs), 29 flame retardants (FRs, including organophosphate and halogenated FRs), 35 pesticides (including 9 pyrethroid insecticides) and 13 personal care products (PCPs, including musks and UV filters), were determined in oysters' tissues collected during one year in four seasonal sampling surveys. The seasonal environmental pollution on the production site was evaluated by water and sediment analysis. Furthermore, oysters' nutritional quality was also assessed and related with the consumption of healthy seafood, showing that oysters are a rich source of protein with low fat content and with a high quality index all year around. Results showed that most analysed pollutants were not detected either in oyster tissues or in environmental matrixes (water and sediments). The few pollutants detected in oyster tissues, including both regulated and non-legislated pollutants, such as a few PAHs (fluorene, phenanthrene, anthracene, fluoranthene, pyrene and indenopyrene), FRs (TPPO, TDCPP, DCP, BDE-47, BDE-209 and Dec 602) and PCPs (galaxolide, galaxolidone, Homosalate and octocrylene), were present at low levels (in the ng/g dw range) and did not represent a significant health risk to humans. The observed seasonal variations related to human activities (e.g. tourism in summer) highlights the need for environmental protection and sustainable resource exploration for safe seafood production.