Level of BPA contamination in resin composites determines BPA release.

OBJECTIVES: Resin composites may release bisphenol A (BPA) due to impurities present in the monomers. However, there is a lack of knowledge regarding the leaching characteristics of BPA from resin composites. Therefore, experimental resin composites were prepared with known amounts of BPA. The objective of this study was (1) to determine which amount of BPA initially present in the material leaches out in the short term and, (2) how this release is influenced by the resin composition. METHODS: BPA (0, 0.001, 0.01, or 0.1 wt%) was added to experimental resin composites containing 60 mol% BisGMA, BisEMA(3), or UDMA, respectively, as base monomer and 40 mol% TEGDMA as diluent monomer. Polymerized samples (n = 5) were immersed at 37 °C for 7 days in 1 mL of water, which was collected and refreshed daily. BPA release was quantified with UPLC-MS/MS after derivatization with pyridine-3-sulfonyl chloride. RESULTS: Between 0.47 to 0.67 mol% of the originally added BPA eluted from the resin composites after 7 days. Similar elution trends were observed irrespective of the base monomer. Two-way ANOVA showed a significant effect of the base monomer on BPA release, but the differences were small and not consistent. SIGNIFICANCE: The released amount of BPA was directly proportional to the quantity of BPA present in the resin composite as an impurity. BPA release was mainly diffusion-based, while polymer composition seemed to play a minor role. Our results underscore the importance for manufacturers only to use monomers of the highest purity in dental resin composites to avoid unnecessary BPA exposure in patients.

Raman silent region - based method for detection of pesticides with cyano group.

Based on the fact that not all chemical substances possess good Raman signals, this article focuses on the Raman silent region signals of pesticides with cyano group. Under the optimized conditions of methanol-water (1:1, v/v) as the solvent, irradiation at 302 nm light source for 20 min, and the use of 0.5 mol/L KI as the aggregating agent, Surface-enhanced Raman spectroscopy (SERS) method for azoxystrobin detection was developed by the Raman silent region signal of 2230 cm-1, and verified by detecting the spiked grapes with different concentrations of azoxystrobin. Other four pesticides with cyano group also could be identified at the peak of 2180 cm-1, 2205 cm-1, 2125 cm-1, and 2130 cm-1 for acetamiprid, phoxim, thiacloprid and cymoxanil, respectively. When azoxystrobin or acetamiprid was mixed respectively with chlorpyrifos without cyano group, their SERS signals in the Raman silent region of chlorpyrifos were not interfered, while mixed with cymoxanil in different ratios (1:4, 1:1 and 4:1), respectively, each two pesticides with cyano group could be distinguished by the changes in the Raman silent region. In further, four pesticides with or without cyano group were mixed together in 1:1:1:1 (acetamiprid, cymoxanil, azoxystrobin chlorpyrifos), and each pesticide still could be identified even at 0.5 mg/L. The results showed that the SERS method combined with UV irradiation may provide a new way to monitor the pesticides with C≡N performance in the Raman silent region without interference from the food matrix.

In vitro and field efficacy of fungicides against sheath blight of rice and post-harvest fungicide residue in soil, husk, and brown rice using gas chromatography-tandem mass spectrometry.

Rice is a staple food for about 65% of the India's population. India ranks first in area under rice and second in production of rice in the world. In India, it is cultivated over 43.39 m ha with a production and productivity of 104.32 million tons and 2404 kg/ha, respectively. Besides ensuring food security of the nation, it is an export commodity and earns a huge foreign exchange. In this study, we investigated the efficacy of five fungicides against Rhizoctonia solani Kuhn AG-1 IA, inciting sheath blight of rice in vitro and under field conditions along with post-harvest residue of the fungicides found effective in disease management. In vitro growth inhibition tests revealed that the EC50 values of azoxystrobin 18.2% + difenoconazole 11.4% SC, pencycuron 22.9% SC, thifluzamide 23.9% SC, hexaconazole 4% + zineb 68% WP, and validamycin 3% L against Rhizoctonia solani ranged from 0.006 to 354.81 ppm a.i., whereas the corresponding EC90 values were 0.758 to 1202.26 ppm a.i. Thifluzamide 23.9% SC was found to be the most inhibitory with EC50 and EC90 values of 0.006 and 0.758 ppm a.i. followed by hexaconazole 4% + zineb 68% WP. The complete inhibition of sclerotia formation was observed at 1 ppm, 20 ppm, and 25 ppm a.i. of thifluzamide 23.9% SC, hexaconazole 4% + zineb 68% WP, and azoxystrobin 18.2% + difenoconazole 11.4% SC, respectively. In field trials, azoxystrobin 18.2% + difenoconazole 11.4% SC was the best treatment in reducing sheath blight and in enhancing grain yield of rice followed by thifluzamide 23.9% SC, pencycuron 22.9% SC, and validamycin 3% L, whereas hexaconazole 4% + zineb 68% WP was the least effective fungicide. Benefit-cost ratio (B:C) of different fungicides reflected that pencycuron 22.9% SC (B:C 5.06) and azoxystrobin 18.2% + difenoconazole 11.4% SC(B:C 4.65) sprayed at single/recommended doses of 1 ml/l were highly economical in managing sheath blight disease of rice. Double dose of pencycuron 22.9% SC further enhanced the B:C to 7.24 while the double dose of azoxystrobin 18.2% + difenoconazole 11.4% SC was less economical (B:C 2.84) compared to their recommended doses. Samples of rice matrices were processed using QuEChERS method and analyzed for the presence of fungicide residues by gas chromatography-tandem mass spectrometry (GC-MS/MS). The post-harvest residues of azoxystrobin, difenoconazole, and pencycuron, sprayed at single/recommended and double doses with a pre-harvest interval (PHI) of 44 days, were found below the limit of quantification (LOQ), i.e., 0.01 and 0.005 mg kg-1 for azoxystrobin and difenoconazole and 0.05 mg kg-1 for pencycuron in brown rice, cropped soil, paddy straw, and husk. These results clearly demonstrated that treatment of azoxystrobin 18.2% + difenoconazole 11.4% SC and pencycuron 22.9% SC could be taken as safe for crop protection and environmental contamination point of view. The findings of this research work will have a positive impact on rice export and use.

Tailored poly(ethylene) glycol dimethacrylate based shape memory polymer for orthopedic applications.

Shape-memory polymers (SMPs) are stimuli-responsive materials known for their outstanding ability to be actuated from temporary shape into original shape. Because of this unique functionality SMPs are promising materials for diverse technological applications including smart biomedical devices. In this article, the work has been focused towards tailoring the SMP precursor and crosslinker wt% to obtain biocompatible acrylate based shape memory polymer with glass transition temperature (Tg) close to human body temperature. Methacrylate based shape memory polymer networks are synthesized via free radical polymerization by varying the wt% of t-butyl acrylate (tBA) and poly(ethylene glycol) dimethacrylate (PEGDMA) as crosslinker. The Tg is found to increase from 28 to 45°C with increasing tBA amount. The SMP synthesized from 70wt% of tBA and 30wt% of PEGDMA possess Tg close to human body temperature and is tested for cytotoxicity with two different cell lineages, osteosarcoma (MG-63) cells, and human keratinocyte (HaCaT) cells. The synthesized SMP is found to be non-cytotoxic. Thus the investigated biocompatible shape memory polymer network can be a promising soft substrate for passive thermomechanical stimulation which can adapt and meet specific needs of in vitro or in vivo orthopedic Superior Labrum Anterior and Posterior (SLAP) medical devices.

Simultaneous Determination of Seven Kinds of Fungicides in Citrus Fruits by Gas Chromatograghy/Mass Spectrometry.

A simple and accurate procedure was developed for the determination of seven fungicides, azoxystrobin (AZO), diphenyl (DP), fludioxonil (FLUDI), imazalil (IMZ), o-phenylphenol (OPP), pyrimethanil (PYRI) and thiabendazole (TBZ), in citrus fruits. The citrus fruit sample was extracted with acetonitrile and cleaned up with a graphite carbon/aminopropyl silanized silica gel solid-phase extraction cartridge using acetonitrile-toluene (3 : 1, v/v) as the eluent. Triphenylene was used as an internal standard (I.S.) at the concentration of 0.5 µg/mL. The sample solution was subjected to GC-MS utilizing the matrix-matched standard solution method. The recoveries of AZO, FLUDI, IMZ, OPP, PYRI and TBZ spiked in domestic citrus fruits (Satsuma mandarin) at the level of 0.01-10.0 µg/g were 72.8-104% and the limits of quantification were 0.01 µg/g. The recoveries of DP spiked in domestic citrus fruits at the level of 0.01-70.0 µg/g were 70.8-80.4% and the limit of quantification was 0.01 µg/g. The proposed method was applied to the determination of fungicides in citrus fruits purchased in various markets.

Determination of methacrylic acid in food simulants by pyrolytic butylation-gas chromatography.

An on-line pyrolytic butylation approach was proposed to determine methacrylic acid (MA) in food simulants by gas chromatography (GC) without an expensive pyrolyzer. MA in food simulants was converted into butyl methacrylate in the presence of tetrabutylammonium hydroxide (TBAH) without any pretreatment at 330°C in the injection-port, contributing to high GC signal response. The derivatizing conditions for the proposed method were optimized, namely the injection-port temperature, type and amount of the organic alkaline used for derivatization. A series of standard solutions of MA in the range of 1.0-50mg/kg were analyzed with correlation coefficient r≥0.9975. The limits of detection (LODs) were less than 0.15mg/kg for MA in four matrix simulants (distilled water, 3%w/v acetic acid, 10%v/v ethanol, and isooctane). Relative standard deviations (RSDs) for retention time, peak height and peak area were all less than 3.88%. The technique was successfully applied to the analysis of MA migrating from plastic cup samples, with recoveries of added MA in the range of 96.5-123.0%. Direct injection of the simulants into the GC system after migration tests, without any pretreatment step, makes the developed method of great value for rapid screening analysis of samples in bulks.

Residual behavior and risk assessment of the mixed formulation of benzene kresoxim-methyl and fluazinam in cucumber field application.

Benzene kresoxim-methyl (BKM) is a new strobilurin fungicide mixed with fluazinam (Flu) into 40 % suspension concentrate (SC) formulation to improve fungicidal efficacy and to reduce the risk of resistance on cucumber. However, the fate of the fungicide residues in a cucumber plantation remains unclear. Thus, an efficient method of ultra-performance liquid chromatography combined with a modified quick, easy, cheap, effective, rugged, and safe sample preparation was developed to simultaneously determine the BKM and Flu residues in cucumber and soil samples to investigate their residual behavior and risk assessment in the cucumber plantation. This analytical method revealed that the detection limits of BKM and Flu were 1.64 × 10(-3) and 1.82 × 10(-3) mg L(-1), respectively, and their average recoveries in the cucumber and soil samples were 77.5-106.9 %. The respective half-lives of BKM and Flu were 2.2-3.4 and 1.0-2.5 days in cucumber; in soil, the half-lives of BKM and Flu were 2.6-5.0 and 2.4-5.3 days, respectively. Seven days after application, the terminal residues of BKM and Flu in cucumber were less than 0.02 mg kg(-1). The residual profiles of BKM and Flu suggested that these fungicides could rapidly degrade in cucumber plantations. Their hazard quotient values were all less than 1 on the preharvest intervals of 3, 5, and 7 days, indicating that the dietary risk of BKM and Flu 40 % SC with the recommended usage on cucumber is negligible.

Simultaneous determination of perfluoroalkyl iodides, perfluoroalkane sulfonamides, fluorotelomer alcohols, fluorotelomer iodides and fluorotelomer acrylates and methacrylates in water and sediments using solid-phase microextraction-gas chromatography/mass spectrometry.

Here, we developed and validated a headspace-solid-phase microextraction-gas chromatography/mass spectrometry (HS-SPME-GC/MS) method for the determination of 14 volatile perfluorinated alkylated substances (PFASs) in water and sediment samples according to SANTE 11945/2015 guidelines. Three fluorotelomer alcohols (FTOHs), two perfluoroalkyl iodides (PFIs), three fluorotelomer iodides (FTIs), four fluorotelomer acrylates and methacrylates (FTACs and FTMACs) and two perfluoroalkyl sulfonamides (FASAs) were analysed simultaneously to assess the occurrence of these compounds from their emission sources to the outlets in water treatment plants. Several SPME parameters were optimised for both water and sediment to maximise responses and keep analysis time to a minimum. In tap water, the limits of quantification (LOQs) were found to be between 20ng/L and 100ng/L depending on the analyte, with mean recoveries ranging from 76 to 126%. For sediments, LOQs ranged from 1 to 3ng/g dry weight depending on the target compound, with mean recoveries ranging from 74 to 125%. SPME considerably reduced sample preparation time and its use provided a sensitive, fast and simple technique. We then used this HS-SPME-GC/MS method to investigate the presence of volatile PFASs in the vicinity of an industrial facility. Only 8:2 FTOH and 10:2 FTOH were detected in a few water and sediment samples at sub-ppb concentration levels. Moreover, several non-target fluorotelomers (12:2 FTOH, 14:2 FTOH and 10:2 FTI) were identified in raw effluent samples. These long-chain fluorotelomers have high bioaccumulative potential in the aquatic environment compared with short-chain fluorotelomers such as 6:2 FTOH and 6:2 FTI.

Zeolitic imidazolate framework-methacrylate composite monolith characterization by inverse gas chromatography.

UNLABELLED: Thermodynamic characterization of butyl methacrylate-co-ethylene dimethacrylate neat monolith and zeolitic imidazolate framework-8 incorporated with butyl methacrylate-co-ethylene dimethacrylate composite monolith were studied using inverse gas chromatography at infinite dilution under 1MPa column pressure and various column temperatures. The free energy of adsorption (ΔGA), enthalpy of adsorption (ΔHA) and entropy of adsorption (ΔSA) were determined using a series of n-alkanes. The dispersive component of surface energy (γS(D)) was estimated by Dorris-Gray and Schultz et al. METHODS: The composite monolith showed a more energetic surface than the neat monolith. The acidic, KA, and basic, KD, parameters for both materials were estimated using a group of polar probes. A basic character was concluded with more basic behavior for the neat monolith. Flory-Huggins parameter, χ, was taken as a measure of miscibility between the probes with the low molecular weight and the high molecular weight monolith. Inverse gas chromatography provides a better understanding of the role of incorporated zeolitic imidazolate framework (ZIF-8) into the polymer matrix in its monolithic form.

Fatty Acid Methyl Ester (FAME) Succession in Different Substrates as Affected by the Co-Application of Three Pesticides.

INTRODUCTION: In intensive agriculture areas the use of pesticides can alter soil properties and microbial community structure with the risk of reducing soil quality. MATERIALS AND METHODS: In this study the fatty acid methyl esters (FAMEs) evolution has been studied in a factorial lab experiment combining five substrates (a soil, two aged composts and their mixtures) treated with a co-application of three pesticides (azoxystrobin, chlorotoluron and epoxiconazole), with two extraction methods, and two incubation times (0 and 58 days). FAMEs extraction followed the microbial identification system (MIDI) and ester-linked method (EL). RESULTS AND DISCUSSION: The pesticides showed high persistence, as revealed by half-life (t1/2) values ranging from 168 to 298 days, which confirms their recalcitrance to degradation. However, t1/2 values were affected by substrate and compost age down to 8 days for chlorotoluron in S and up to 453 days for epoxiconazole in 12M. Fifty-six FAMEs were detected. Analysis of variance (ANOVA) showed that the EL method detected a higher number of FAMEs and unique FAMEs than the MIDI one, whereas principal component analysis (PCA) highlighted that the monosaturated 18:1ω9c and cyclopropane 19:0ω10c/19ω6 were the most significant FAMEs grouping by extraction method. The cyclopropyl to monoenoic acids ratio evidenced higher stress conditions when pesticides were applied to compost and compost+soil than solely soil, as well as with final time. CONCLUSION: Overall, FAMEs profiles showed the importance of the extraction method for both substrate and incubation time, the t1/2 values highlighted the effectiveness of solely soil and the less mature compost in reducing the persistence of pesticides.

In-package nonthermal plasma degradation of pesticides on fresh produce.

In-package nonthermal plasma (NTP) technology is a novel technology for the decontamination of foods and biological materials. This study presents the first report on the potential of the technology for the degradation of pesticide residues on fresh produce. A cocktail of pesticides, namely azoxystrobin, cyprodinil, fludioxonil and pyriproxyfen was tested on strawberries. The concentrations of these pesticides were monitored in priori and post-plasma treatment using GC-MS/MS. An applied voltage and time dependent degradation of the pesticides was observed for treatment voltages of 60, 70 and 80 kV and treatment durations ranging from 1 to 5 min, followed by 24h in-pack storage. The electrical characterisation revealed the operation of the discharge in a stable filamentary regime. The discharge was found to generate reactive oxygen and excited nitrogen species as observed by optical emission spectroscopy.

Determination of strobilurin fungicides in cotton seed by combination of acetonitrile extraction and dispersive liquid-liquid microextraction coupled with gas chromatography.

The simultaneous determination of four strobilurin fungicides (picoxystrobin, kresoxim-methyl, trifloxystrobin, and azoxystrobin) in cotton seed by combining acetonitrile extraction and dispersive liquid-liquid microextraction was developed prior to GC with electron capture detection. Several factors, including the type and volume of the extraction and dispersive solvents, extraction condition and time, and salt addition, were optimized. The analytes were extracted with acetonitrile from cotton seed and the clean-up was carried out by primary secondary amine. Afterwards, 60 µL of n-hexane/toluene (1:1, v/v) with a lower density than water was mixed with 1 mL of the acetonitrile extract, then the mixture was injected into 7 mL of distilled water. A 0.1 mL pipette was used to collect a few microliters of n-hexane/toluene from the top of the aqueous solution. The enrichment factors of the analytes ranged from 36 to 67. The LODs were in the range of 0.1 × 10(-3) -2 × 10(-3) mg/kg. The relative recoveries varied from 87.7 to 95.2% with RSDs of 4.1-8.5% for the four fungicides. The good performance of the method, compared with the conventional pretreatments, has demonstrated it is suitable for determining low concentrations of strobilurin fungicide residues in cotton seed.

In vitro cellular detoxification of triethylene glycol dimethacrylate by adduct formation with N-acetylcysteine.

OBJECTIVE: Various protective effects of N-acetylcysteine (NAC) against triethylene glycol dimethacrylate (TEGDMA)-induced cell damage have been demonstrated, but so far there is no evidence on NAC direct monomer detoxification mechanism. Here, we hypothesized that NAC might reduce TEGDMA cytotoxicity due to direct NAC adduct formation. METHODS: We measured the cytotoxic effects of TEGDMA in presence and in absence of NAC by MTT test. Then we analyzed the presence of TEGDMA-NAC adduct formation in extracellular and intracellular compartments by capillary electrophoresis-UV detection (CE-UV) and capillary electrophoresis-mass spectrometry (CE-MS) analytical techniques. Moreover, we quantified the effective intracellular and extracellular TEGDMA concentrations through HPLC in the presence and absence of 10 mmol/L NAC. RESULTS: TEGDMA reduced 3T3 cell vitality in a dose- and time-dependent manner, while NAC decreased monomer cytotoxicity and extracellular monomer concentrations by a direct reaction with TEGDMA. The adducts between the two molecules were detected both in the presence and absence of cell. Moreover a signal ascribed to the methacrylic acid was present in the CE-UV electropherogram of cellular lysates obtained after incubation with TEGDMA. SIGNIFICANCE: Our results suggest that in vitro detoxification capability of NAC against TEGDMA-induced cell damage might occur also through the formation of NAC-TEGDMA adduct.

Effect of household and commercial processing on acetamiprid, azoxystrobin and methidathion residues during crude rapeseed oil production.

Rape crops with residues of acetamiprid, azoxystrobin and methidathion incurred from field trials were used to evaluate the effect of household and commercial crude rapeseed oil processing on the transfer of pesticide residues. The pesticides were applied at exaggerated dosage to quantify residue levels in processed samples. The processing procedure was conducted as closely as possible to the actual conditions in practice. The conditioning step removed at least 30% of pesticides, while azoxystrobin and methidathion were concentrated by at least 15% at the single pressing step. The residue level of methidathion was concentrated with a processing factor (PF) of 1.07, while azoxystrobin and acetamiprid decreased with PFs of 0.67 and 0.04, respectively, after all processing procedures. The overall magnitudes of acetamiprid, azoxystrobin and methidathion in rapeseed oil and meal were all decreased after processing compared with the magnitude of those in raw rapeseed.

Evaluation of polypropylene and poly (butylmethacrylate-co-hydroxyethylmethacrylate) nonwoven material as oil absorbent.

Polypropylene (PP) and poly(butylmethacrylate-co-hydroxyethylmethacrylate) (PBMA-co-HEMA) nonwoven materials as oil absorbents have been fabricated for the first time via melt blown method. As-prepared nonwovens were investigated in terms of mass per unit area, density, air permeability, contact angle, and morphology observations for fiber diameter distribution and single fiber surface by a field emission scanning electron microscope. The nonwovens are demonstrated as fast and efficient absorbents for various kinds of oils with oil absorbency up to seven to ten times their own weight. The nonwovens show excellent water repulsion but superoleophilic properties. The measured contact angles for water and toluene are more than 127° and ca. 0°, respectively. The addition of PBMA-co-HEMA makes the nonwoven surface more hydrophobic while conserving superoleophilicity. Compared with PP nonwoven, broad diameter distribution of the blend nonwoven is attributed to poor melt fluidity of PBMA-co-HEMA. In terms of single fiber, coarse surface and the presence of point-like convexities lead to the fibers being more readily wetted by oil. More interesting, oil-water separation and oil recovery can be easily carried out by filter and absorption-desorption process, the recovered materials contained hardly any oil droplet and could be reused for next cycles.

Determination of monomer conversion in methacrylate-based polymer monoliths fixed in a capillary column by pyrolysis-gas chromatography.

Monomer conversion and the resultant copolymer composition of polymer monolith columns are important factors for controlling column characteristics. We propose a new method to determine monomer conversion to a polymer monolith fixed in a capillary column using pyrolysis-gas chromatography. Small pieces of a poly(butyl methacrylate-co-ethylene dimethacrylate (BMA-co-EDMA)) monolith column were pyrolyzed at 450°C with poly(ethyl methacrylate) as a non-volatile internal standard. The monomer conversions were estimated from the corresponding relative peak intensities in the pyrogram. It was determined that the conversion of EDMA was significantly greater than that of BMA in a low-conversion UV-polymerized poly(BMA-co-EDMA) monolithic capillary column.

Antiproliferative activity and apoptosis induction of Eucalyptus Citriodora resin and its major bioactive compound in melanoma B16F10 cells.

Antiproliferative activity and apoptosis induction of ethyl acetate of Eucalyptus citriodora resin (EAEER), and its major bioactive compound in melanoma B16F10 cells were investigated. 6-[1-(p-Hydroxy-phenyl)ethyl]-7-O-methyl aromadendrin (HEMA), a flavanol derivative, was isolated from EAEER and identified on the basis of its mass and NMR spectra. The results from MTT assay showed high antiproliferative effects of EAEER and HEMA on B16F10 cells. Moreover, EAEER- and HEMA-induced cell apoptosis was association with the decrease in the mitochondrial transmembrane potentials (Δψ(m)), increase in Bax/Bcl-2 ratio, and activation of caspase-3. Cells treated with EAEER and HEMA generated intracellular reactive oxygen species (ROS) and nitric oxide (NO), indicating that ROS and RNS play important roles in the induction of apoptosis in B16F10 cells. Taken together, EAEER and its major bioactive compound, HEMA, inhibited the proliferation of B16F10 cells via apoptosis and may be a potential antimelanoma agent.

[Determination of 9 residual acrylic monomers in acrylic resins by gas chromatography-mass spectrometry coupled with microwave assisted extraction].

A reliable gas chromatography-mass spectrometry (GC-MS) method was developed for the determination of 9 residual acrylic monomers (methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl acrylate, butyl methacrylate, styrene, acrylic acid and methacrylic acid) in acrylic resins. Solid resin was precipitated with methanol after microwave assisted extraction with ethyl acetate for 30 min, and liquid resin was diluted with methanol directly. The nine acrylic monomers got a good separation within 20 min on a DB-WAX column. The limits of quantification (LOQs, S/N = 10) of the method were in the range of 1-10 mg/kg for liquid resin and 3-50 mg/kg for solid resin. The calibration curves were linear within 1-500 mg/L range with correlation coefficients above 0. 995. The recoveries ranged from 84.4% to 108.6% at five spiked levels. The sensitivity, recovery and selectivity of the method can fully meet the requirements of practical work.

Análise da citoxicidade e do grau de conversão de resinas compostas de metacrilato e de silorano / Analysis of the cytotoxicity and the degree of conversion of composite resins based methacrylate and silorane

Compósitos a base de Silorano vêm apresentando bons resultados mecânicos em diversos estudos laboratoriais, mas pouco se sabe ainda sobre seus efeitos sobre as células do tecido gengival e seu grau de conversão. O objetivo deste estudo foi avaliar a viabilidade celular e o grau de conversão de uma resina composta a base de silorano (Filtek P90- 3M ESPE) e de três resinas convencionais de metacrilato (Filtek Z350XT- 3M ESPE; Filtek Z100- 3M e Filtek Z250-3M ESPE), todas fotopolimerizadas por 20 ou 40 segundos pelo LED (Flash lite DISCUS), em cultura primária de fibroblastos gengivais. Avaliou-se também se existe correlação entre grau de conversão e viabilidade celular...

Multiresidue method for the determination of 13 pesticides in three environmental matrices: water, sediments and fish muscle.

Pesticides residues in aquatic ecosystems are an environmental concern which requires efficient analytical methods. In this study, we proposed a generic method for the quantification of 13 pesticides (azoxystrobin, clomazone, diflufenican, dimethachlor, carbendazim, iprodion, isoproturon, mesosulfuron-methyl, metazachlor, napropamid, quizalofop and thifensulfuron-methyl) in three environmental matrices. Pesticides from water were extracted using a solid phase extraction system and a single solid-liquid extraction method was optimized for sediment and fish muscle, followed by a unique analysis by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Limits of quantification were below 5 ng L(-1) for water (except for fluroxypyr and iprodion) and ranged between 0.1 ng g(-1) and 57.7 ng g(-1) for sediments and regarding fish, were below 1 ng g(-1) for 8 molecules and were determined between 5 and 49 ng g(-1) for the 5 other compounds. This method was finally used as a new routine practice for environmental research.