Effect of temperature,collection mode,and modifier on the supercritical CO2 extraction of dicofol residues from fish samples

Toxicity evaluation of Dicofol to Astyanax bimaculatus schubarti, a characteristic fish species living in tropical rivers and lakes was carried out through LC₅₀ – 96 Hours. These experiments were performed under laboratory controlled conditions with atmospheric air flow and dilution water at 25°C in the static mode, supercritical fluid extraction (SFE) with pure CO₂ and CO₂ modified with hexane and methanol were used at 50, 70, 80, and 100°C and 300 atm. Several collection modes were studied to extract Dicofol from fish samples. The extraction efficiencies were directly comparedd with those obtained after 8 h of Soxhlet extraction using the same clean-up with Florisil and analysis by HRGC/ECD and HRGC/MS as a confirmatory analytical technique. The SFE recoveries at temperatures lower than 80°C were typically lower than soxhlet recoveries; however a temperature increase enhanced the efficiency of SFE. The results showed that under certain conditions, supercritical fluid gave higher extractio power (extracted 11 % more pesticide), shorter extraction time, and lower solvent consumption than Soxhlet, thus affording an excellent alternative to the conventional method for extracting Dicofol from fish sample.     

Determination of simple bromophenols in marine fishes by reverse-phase high performance liquid chromatography (RP-HPLC)

Brominated phenols 2- and 4-bromophenol (2-BP and 4-BP); 2,4- and 2,6-dibromophenol (2,4-DBP and 2,6-DBP) and 2,4,6-tribromophenol (2,4,6-TBP) have been identified as key flavor compounds found in seafoods. Depending on their concentrations, they were responsible for marine or ocean flavor (shrimp/crab/fish/sea salt-like) or for phenolic/iodine/iodoform-like off-flavor. In this work a new analytical methodology was developed to determine, simultaneously, such bromophenols in fish meats, based on reversed-phased high-performance liquid chromatographic separation (RP-HPLC). The separation of bromophenols was made onto a Lichrospher 100 RP-18 column using water:acetonitrile gradient at a flow rate of 1.0 mL min⁻¹, using absorbance detection at 286 nm, were the 2-BP, 4-BP, 2,4- and 2,6-DBP show significant absorbtivity values and at 297 nm for 2,4,6-TBP. They were separated in 20 min with a good chromatographic resolution (Rs) for the isomeric compounds: 2- and 4-BP, Rs = 1.23; 2,4- and 2,6-DBP, Rs = 1.63. The calibration curves were linear in the bromophenols concentration range of 200.0-1000 ng mL⁻¹. Under optimized conditions, the detection limit of the HPLC method was 127 ng mL⁻¹ for 2-BP; 179 ng mL⁻¹ for 4-BP; 89.0 ng mL⁻¹ for 2,4-DBP; 269 ng mL⁻¹ for 2,6-DBP and 232 ng mL⁻¹ for 2,4,6-TBP. This method has been applied in determination of bromophenols, isolated by combined steam distillation-solvent extraction with 2 mL of pentane/diethyl ether (6:4), from Brazilian fishes samples, collected on the Atlantic coast of Bahia (13°01′S and 38°31′W), Brazil. The concentration range determined were 0.20 ng g⁻¹ (2-BP) to 299 ng g⁻¹ (2,4,6-TBP). The method proposed here is rapid and suitable for simultaneous quantification of simple bromophenols in fish meat. As long as we know, it is the first analytical methodology, using RP-HPLC/UV, which was developed to determine simple bromophenols in fish meat.     

Titanium dioxide as an adsorbent to enhance the detection ability of near-infrared diffuse reflectance spectroscopy

A method for quantitative determination of fish sperm deoxyribonucleic acid(fsDNA) was developed by using titanium dioxide(TiO2) as an adsorbent and near-infrared diffuse reflectance spectroscopy(NIRDRS). The selective enrichment of fsDNA was proved by comparing the adsorption efficiency of bovine serum albumin, tyrosine and tryptophan, and the low adsorption background of TiO2 was illustrated by comparing the spectra of four commonly-used inorganic adsorbents(alkaline aluminium oxide, neutral aluminium oxide, nano-hydroxyapatite and silica). The spectral feature of fsDNA can be clearly observed in the spectrum of the sample. Partial least squares(PLS) model was built for quantitative determination of fsDNA using 28 solutions, and 13 solutions with interferences were used for validation of the model. The results showed that the correlation coefficient(R) between the predicted and the reference concentration is 0.9727 and the recoveries of the validation samples are in the range of98.2%–100.7%     

Combined biological and chemical assessment of estrogenic activities in wastewater treatment plant effluents

Five wastewater treatment plant effluents were analyzed for known endocrine disrupters and estrogenicity. Estrogenicity was determined by using the yeast estrogen screen (YES) and by measuring the blood plasma vitellogenin (VTG) concentrations in exposed male rainbow trout (Oncorhynchus mykiss). While all wastewater treatment plant effluents contained measurable concentrations of estrogens and gave a positive response with the YES, only at two sites did the male fish have significantly increased VTG blood plasma concentrations after the exposure, compared to pre-exposure concentrations. Estrone (E1) concentrations ranged up to 51 ng L^–1, estradiol (E2) up to 6 ng L^–1, and ethinylestradiol (EE2) up to 2 ng L^–1 in the 90 samples analyzed. Alkylphenols, alkylphenolmonoethoxylates and alkylphenoldiethoxylates, even though found at µg L^–1 concentrations in effluents from wastewater treatment plants with a significant industrial content, did not contribute much to the overall estrogenicity of the samples taken due to their low relative potency. Expected estrogenicities were calculated from the chemical data for each sample by using the principle of concentration additivity and relative potencies of the various chemicals as determined with the yeast estrogen screen. Measured and calculated estradiol equivalents gave the same order of magnitude and correlated rather well (R ²=0.6).An erratum to this article can be found at     

Synthesis and characterization of zeolite Linde Type W and its metal oxide composite Ag-O-LTW used for the decontamination of chemical warfare agent simulant

Abstract

In this study, we have evaluated the performance of novel adsorbent zeolite Linde Type W and modified LTW with AgO metal oxide composite for the decontamination of chemical warfare agent simulant 2-chloroethylphenylsulphide (CEPS). Zeolites are nanoporous aluminosilicate minerals composed of silicon, aluminum and oxygen framework with cations and water molecules within the pores. The synthesized zeolite LTW and its composites Ag-O-LTW was characterized by XRD, FTIR, SEM-EDS and BET analytical techniques. The decontamination study of CWA simulant, CEPS was monitored by using GC-FID technique. The nanocrystalline zeolite LTW and Ag-O-LTW composites were found powerful adsorbents and showed great decontamination potential toward CWA simulant CEPS. The Ag-O-LTW showed better results (～98 % decontamination in 7?hours) than LTW zeolite.     

Effective removal of adhering cells via ultrashort laser pulses

A technique for accurately and effectively removing adhering red blood cells in a blood plasma thin film via a picosecond pulsed laser was developed. The laser beam was focused to the surface of the film to generate plasma-mediated ablation and an automated stage was employed for raster scan. The SEM images showed that the red blood cells distributed in the ablation scanned area were removed neatly, leaving the surroundings and the film base intact. For cells across the boundary between the ablated and untreated areas, a trim cutting interface was observed. Complete ablation of red blood cells in the target area is achieved without visible thermal and collateral damage in the remaining structure. The removal method is very effective because it is not necessary to selectively focus a laser beam on individual target cells and remove cells one by one. The ablation is scanned over a certain size of area, enabling practical cell killing or microbial decontamination in clinical/industrial scale.     

NaF+HNO3浸泡法去除金属部件表面241Am污染

241Am是极毒、亲骨超钚核素,主要发射5.49MeVα粒子和59.6keV的γ射线,半衰期为423年。曾经作为烟雾探测器广泛地应用于火灾报警器生产中,长期的生产造成了生产线各个部位,尤其是金属部件表面存在较为严重的放射性污染。在其生产线退役过程中,需要对这些污染表面进行去污以减少操作人员受照剂量和退役过程废物产生量。放射性污染的去污按去污机理可分为机械法、化学法、物理法和电化学法等[1]。其中化学浸泡去污在核设施退役中应用较为广泛[2]。NaF HNO3浸泡去污工艺早期由前苏联开发,针对的去污对象主要为不锈钢,开始采用的试剂组成为3…     

Conversion of waste meat to resources by enzymatic reaction under high pressure carbon dioxide conditions

ABSTRACT

Every year, a tremendous amount of meat is wasted, which may have adverse effects on the environment. Therefore, waste meat should be recycled. Building a recycling system for waste meat to reduce financial loss and careful treatment of life-based resources is essential. As meat contains abundant amino acids, it can be used as an immense source of amino acids for other industries following enzymatic hydrolysis. However, during the enzymatic hydrolysis process, the waste meat can easily get contaminated by microbes and therefore needs high temperature. In the present study, we applied high pressure carbon dioxide (HPCD) technology to prevent the contamination of meat by microbes during enzymatic hydrolysis process. According to our research, HPCD has a great potential to be adopted as a novel decontamination technology in the industrial enzymatic hydrolysis process at relatively lower temperature.     

Modeling a swimming fish with an initial boundary value problem: Unsteady maneuvers of an elastic plate with internal force generation

In order to model unsteady maneuvers in swimming fish, we develop an initial-boundary value problem for a fourth-order hyperbolic partial differential equation in which the fish's body is treated as an inhomogeneous elastic plate. The model is derived from the three-dimensional equations of elastic dynamics, and is essentially a simple variant of the classical Kirchhoff model for a dynamic plate. The model incorporates body forces generating moment to simulate muscle force generation in fish. The initial-boundary value problem is reduced to a beam model in one spatial dimension and formulated computationally using finite differences. Interaction with the surrounding water is represented by nonlinear viscous damping. Two example applications using simple but physically reasonable physiological parameters are presented and interpreted. One models the acceleration from rest to steady swimming, the other a rapid turn from rest.     

Multiresidue determination of organochlorines in fish oil by GC-MS: A new strategy in the sample preparation

A rapid, economic and environmentally friendly analytical methodology has been implemented for the determination of α-, β-, γ- and δ-HCH, p,p′-DDT, p,p′-DDD and p,p′-DDE, PCBs congeners #28, #52, #101, #153, #138 and #180 and Hexachlorobenzene in fish oil. 1,2,3,4-Tetrachloronaphtalene was used as internal standard. The sample preparation, consisting of a single step of clean-up and fractionation, took place in a column filled with different layers of neutral and sulphuric acid modified silica. The analytes were eluted by vacuum with of hexane. Significant reduction in terms of solvents, sorbents, and analysis time was achieved in comparison with literature.Gas chromatography coupled to mass spectrometry was used for the separation and determination of the analytes. The instrumental limits of detection were from 0.1 to 1.3 ng mL⁻¹ and the response of the detector was linear up to 200 ng mL⁻¹. The separation proved to be precise (RSD < 3.7% in peak area) and robust in terms of peak area, peak efficacy and resolution. The methodology was validated with two certified reference materials of cod liver oil, BCR 598 and BCR 349, obtaining no statistically significant differences between the concentrations found and certified. For the analytes that were not certified, aliquots of the reference materials were spiked and the recoveries obtained were satisfactory. These results were consistent with those found previously for DDTs by gas chromatography with an electron-capture detector.The methodology was applied to the analysis of three fish oil pills sold in Spain as a dietary supplement of vitamins and omega-3 fatty acids. The sum of the analytes studied was from 64 to 80 ng g⁻¹. The most abundant compounds are PCBs, followed by DDTs in all samples.