Solvent Soxhlet Extraction Research Articles

Influence of the extraction process on the chemical composition and oxidation state of baobab (Adansonia digitata L.) seed oil

Baobab oil is nowadays highly prized by local populations as well as the cosmetic industry. It is a rare oil due to the low oil content of the seeds of the baobab fruit (Adansonia digitata L.). To obtain this oil, the collected seeds were cleaned and ground into powder. Then, the extraction was done by pressing and solvent. The aim of this study is to assess the impact of the extraction method on the composition of baobab oil. According to the results obtained, the solvent extraction process has an influence on the fatty acid composition, especially for oleic (36.42 vs 37.40) % and linoleic (26.85 vs 25.21) % acids. We note a significant difference in the total sterol in favor of the solvent extraction process (370.02 mg.100.g-1 for the oil obtained by pressing against 458.14 mg.100.g-1 for the oil obtained by solvent). Solvent extraction drastically reduces total tocopherols from 1562.4 mg.kg-1 to 547.6 mg.kg-1. The chlorophyll content decreases slightly. However, the carotenoid content increases slightly with solvent extraction. According to the results obtained, the soxhlet solvent extraction process has an effect on the chemical composition of the oil. The heat contributes to the oxidation of the oil and the reduction of sensitive elements such as tocopherols.

Phytochemical Profiling and Cytotoxicity Evaluation of Wrightia tinctoria Extracts on Vero Cell Lines: A Comparative Analysis and Insight into the Bioactive Compounds

Introduction: The utilisation of plant-based medicine is a continuing practice that remains prevalent even with modern times. Some therapeutic modalities have a long history, while others are quite recent. The lack of sufficient reporting on the utilisation of medicinal plants has resulted in an ongoing deficit in the understanding of their therapeutic benefits, as well as, their potential short-term and long-term side-effects. The Sweet Indrajao, commonly known as Pala Indigo Plant or Dyer’s Oleander, and scientifically identified as Wrightia tinctoria R. Br, is a member of the Apocynaceae family. It is known as the “Cure for jaundice tree” in southern India. Wrightia is a plant commonly found in India and Burma. The Wrightia tinctoria plant has been chosen for this study due to its long-standing medicinal usage and the variety of pharmacologically active compounds it contains. Despite of the fact, it is been widely used for medicinal uses, the information concerning its safety mentioned in the literature is scarce, particularly its cytotoxic effects on normal cellular systems, which this research aims to address. Aim: The study was aimed to analyse the therapeutic potential of Wrightia tinctoria plant extracts by evaluating the phytochemical composition and to assess the effect of the Wrightia tinctoria plant extracts on Vero cell lines, for a clearer understanding of its medicinal application and its safety profile. Materials and Methods: This in-vitro study was conducted at SRM Institute of Science and Technology, Chennai and the duration of the study was eight months (Jan to August 2023). For the phytochemical analysis of Wrightia tinctoria, dried plant material (leaves) was collected shade dried and extracted using Soxhlet solvent extraction methods followed by fractionation using techniques like column chromatography. Ethanol, ethyl acetate and aqueous solvents were used for the in-vitro study. The various standard protocols were employed to identify phytoconstituents. The cytotoxicity analysis on Vero cell line (Kidney epithelial cells of African green Monkey) was performed using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2Htetrazolium bromide) assay, where vero cells were cultured and seeded into 96-well microtitre plates. Different concentrations of Wrightia tinctoria extract were added to the wells, followed by incubation. After incubation, MTT solution was added, and formazan crystals formed by viable cells were solubilised using a suitable solvent. Absorbance was measured at a specific wavelength using a microplate reader to assess cell viability and cytotoxic effects. Results: Phytochemical analysis revealed the presence of phenols, steroids, terpenoids, alkaloids, flavonoids, and glycosides. Of the three solvents used in the study, ethanolic extract yielded maximum amount of phytochemicals when compared with the other solvents (aqueous and ethyl acetate) that were investigated. MTT assay was used to determine the cytotoxicity and the Wrightia tinctoria ethanolic extract demonstrated Half maximal Inhibitory concentration (IC50) >100, ensuring the safety profile of the extract on normal cells. Conclusion: Wrightia tinctoria was a significant plant with highly potent phytochemicals with therapeutic properties. Moreover the extract was also safe against the normal cell line (vero cell line).

Pengaruh Proses N-Hexane Solvent Extraction pada Ekstraksi Bitumen dari Aspal Buton sebagai Bahan Baku Minyak Bumi Nonkonvensional

Buton tar sand or commonly known as asbuton is a natural tar sand deposit found in Buton Island, Southeast Sulawesi. The reserve of asbuton is approximately 179.1 million tons with a hypothetical resource of oil amounting to 10,577,646,000 liters. Asbuton is potentially used as an alternative raw material for non-conventional oil. Non-conventional oil from asbuton could be used as a substitute to the depleted resources of conventional oil in Indonesia. Asbuton non-conventional oil could be prepared by extracted bitumen, a heavy hydrocarbon material in asbuton tar sand from its mineral. The bitumen then could be further processed to produce non-conventional oil. Various studies have been carried out to extract bitumen with various solvents. This study uses direct extraction and soxhlet extraction methods with n-hexane solvent to obtain the most optimum percentage of bitumen. Direct extraction method is done by varying the temperature (40, 45, 50, 55, 60oC) and the weight ratio of asphalt and n-hexane solvent (1:20; 1: 30; 1:40; 1:50). Based on the results of research that has been done, the highest percentage of bitumen yield is formed at 40oC and at a ratio of 1:20 that is 88.60% for the direct extraction method. The 1:40 ratio of soxhlet solvent extraction has the highest bitumen yield of 90.97%. After that, a characteristic analysis was carried out using FTIR with a strong absorbance in the area of 1423.47; 1033.85; 873.75; 709.80 cm-1 representing the C-H and C = H groups.

Determinación de timol y carvacrol en una matriz orgánica de alimento para cerdo utilizando Headspace SPME-GC-MS

In recent years, oregano essential oil has been used as an animal food additive due to its antifungal and antibacterial properties as well as s synthetic antibiotic substitute. It is desirable to develop fast and effective thymol and carvacrol quantification method in a swine feed organic matrix. In this work, a performance comparison between the Soxhlet solvent extraction technique using petroleum ether and ethyl acetate and the head space-solid phase microextraction (HS-SPME) technique is made. A 24 design of experiments is performed for defining HS-SPME parameters: equilibrium temperature of 40 ºC, extraction temperature of 40 ºC, ionic strength of 0.57 M, and extraction time of 40 min. The HS-SPME method is more efficient for extracting thymol and carvacrol extraction from an organic matrix. Limits of detection and quantification values using Soxhlet extraction with ethyl acetate were 3.7 and 12.5 μL-1 for thymol and 1.4 and 4.7 μg L-1 for carvacrol, respectively; while LOD and LOQ for HS-SPME were 0.9 and 3.1 μg L-1 for thymol and 0.6 and 1.9 μg L-1 for carvacrol, respectively. The head space-solid phase microextraction method has the potential for quality control in the industry for active compounds present in oregano’s essential oil as an additive into an organic matrix.

Extraction and physicochemical characterization of cashew nut-shell liquid in metal forming

ABSTRACT: Effective lubrication during metal working is critical to mitigating undesirable tool wear and poor surface finish of formed components. This paper investigated the physicochemical characteristics of cashew nut-shell-liquid (CNSL) with a view of determining its suitability for the development of an eco-friendly lubricant used in metal forming. The cashew nut shell oil (CNSO) was extracted by soxhlet method and characterised to determine its physicochemical properties including density, free fatty acid (FFA), and viscosity. In addition, the saponification value, iodine value, pH, flash point and friction coefficient were determined using relevant analytical tools. The results showed that CNSL yield from soxhlet solvent extraction is 45.6%, which is adjudged to be relatively substantial with regard to other extraction processes. Furthermore, the CNSL exhibited critical lubrication characteristics in terms of density (0.94 g/cm3), moisture content (3.96%), acid value (11.32 mg.KOH/g), FFA (3.7%), ester value (127.92 mg.KOH/g), saponification value (139.24 mg.KOH/g), pH value (4.61), iodine value (40.21 gI2/100 g), viscosity at 100 oC (14.12 Pa.s), friction coefficient (0.001) and flash point of 286.63 oC. Given these outcomes in comparison with commercial Chevron soluble oil, it is concluded that CNSL is suitable for use as a viable metal forming lubrication fluid.

Kariya Biodiesel Process Optimization Using Kariya Pod-husks Bio-catalyzed

In this study, biodiesel was produced from underutilized kariya oilseed using ethanol in the presence of kariya pod-husks bio-catalyst. The oil used was extracted through the soxhlet solvent extraction approach. Transesterification of kariya seed oil was investigated using Central Composite Design (CCD) of Response surface methodology. Process factors such as reaction temperature (65, 70, and 85oC), reaction time (2, 3, and 4 h), and ethanol/kariya oil molar ratio (8:1, 10:1, and 12:1) were modeled based on CCD experimental design. The fuel properties of biodiesel produced, and its blends with petrol-diesel were determined. The average yield of extracted kariya oil was 32.55 wt. %. Based on the results, biodiesel yield of 94.41 wt.% was obtained at optimal conditions; a temperature of 75oC, time of 2 h, and ethanol: oil mole ratio of 10:1 at catalyst loading of 5 wt.%. The physicochemical and fuel properties of produced biodiesel and its blend were well within American Society for Testing and Materials (ASTM D6751) standard and compared favorably with petrol-diesel.

Assessing Leachable Cytotoxicity of 3D-Printed Polymers and Facile Detoxification Methods.

Additive manufacturing of polymers is gaining momentum in health care industries by providing rapid 3D printing of customizable designs. Yet, little is explored about the cytotoxicity of leachable toxins that the 3D printing process introduced into the final product. We studied three printable materials, which have various mechanical properties and are widely used in stereolithography 3D printing. We evaluated the cytotoxicity of these materials through exposing two fibroblast cell lines (human and mouse derived) to the 3D-printed parts, using overlay indirect contact assays. All the 3D-printed parts were measured toxic to the cells in a leachable manner, with flexible materials more toxic than rigid materials. Furthermore, we attempted to reduce the toxicity of the 3D-printed material by employing three treatment methods (further curing, passivation coating, and Soxhlet solvent extraction). The Soxhlet solvent extraction method was the most effective in removing the leachable toxins, resulting in the eradication of the material's toxicity. Passivation coating and further curing showed moderate and little detoxification, respectively. Additionally, mechanical testing of the materials treated with extraction methods revealed no significant impacts on its mechanical performances. As leachable toxins are broadly present in 3D-printed polymers, our cytotoxicity evaluation and reduction methods could aid in extending the selections of biocompatible materials and pave the way for the translational use of 3D printing.

Characterization of biologically active compounds from different herbs: Influence of drying and extraction methods

The hot air (HA) method is the most widely implemented drying method for plants (herbs, vegetables, and fruits). This method has a few drawbacks that include long drying time, limited heat transfer, and limited thermal conductivity. This study investigated the effects of HA and infra-red (IR) heating method on biologically active compounds from different herbs (Khaffir lime, Lemongrass, Prai, Tamarind, and Turmeric). The efficiency of the drying methods was evaluated by considering (a) moisture ratio (MR), (b) specific energy consumption (SEC, MJ/kg.H2O), (c) moisture diffusivity (Deff), and (d) activation energy (Ea, kJ/mol). The active compounds were extracted from HA and IR dried herbs using different solvents (hexane, water, and ethanol) through Solid-Liquid Extraction (SLE) and Soxhlet Solvent Extraction (SSE) methods. The moisture removal in the IR drying process increased 10–11% for the herb samples. Specific energy consumption (SEC) increase during the IR drying process is attributed to the rapid evaporation of water at shorter time intervals than HA. Activation energy (Ea) values decreased by 1.66, 1.48, 2.24, 3.13, and 2.07 fold times for IR dried prai, turmeric, lemongrass, tamarind, and kaffir lime, respectively. The higher yields of herbal extracts and the abundance of bioactive terpene derivatives in hexane extracts were obtained from HA herbs compared to IR samples. Therefore, it is concluded that the IR method and SSE process using hexane was suitable to dry and retain the bioactive active compounds within herbs. Further, the IR method over the HA method was considered based on energy consumption, processing time, yield, and active compounds.

Preparationand Physico-Chemical Properties Evaluation of Biodiesel from Pithraj (Aphanamixis Polystachya)Seeds available in Bangladesh

In this study, Pithraj (Aphanamixis polystachya) seed (PS) oil was used to produce biodiesel via trans-esterification process. The PS oil was extracted from seed using a soxhlet solvent extraction technique and the effect of temperature and heating rate on product distribution was investigated. The PS oil was pretreated (esterified) to combat the saponification reaction and other associated problems e.g., phase separation. The transesterification reactions were carried out and the optimum biodiesel yield was found 93.87%, when the reaction condition was as follows: addition of 50 wt.% methanol, 0.8 wt.% NaOH (both are on the basis of wt.% of PS oil addition), 60 °C reaction temperature and 90 min reaction time. Biodiesel produced from PS oil was characterized by various physico-chemical means and compared with international standards. The use of the produced biodiesel in blend with commercial diesel will bring a remarkable change in fuel economy of the country, will ensure a clean and safe environment and will demonstrate a way for ‘Waste to Energy’.
 Chemical Engineering Research Bulletin 21(2020) 43-48

Network Mesh Nanostructures in Cross‐Linked Poly(Dimethylsiloxane) Visualized by AFM

AbstractMesh network structures are visualized by peak force tapping atomic force microscopy on cross‐linked poly(dimethylsiloxane) (PDMS) at the nanometer length scale. The images directly capture network mesh structures with mesh diameter values, from 10 to 16 nm at the free surface of PDMS. Perpendicular to the free surface, in cross‐sectional areas exposed by cryo‐fracturing, similar mesh structures are observed. When exposed to uniaxial stress, the circular mesh features become elongated, showing network deformation at the nanoscale, as a result of mechanical stress. Following Soxhlet solvent extraction the mesh‐like appearance remains unchanged, but mesh diameter values decrease, which are attributed to the removal of non‐crosslinked chains and silica filler.

A comprehensive characterization of non-edible lignocellulosic biomass to elucidate their biofuel production potential

It is very requisite to demonstrate the characterization of lignocellulosic biomass for converting into renewable fuels and valuable chemicals. In this work, the physicochemical and thermochemical characterization of some non-edible oil seeds such as Putranjiva (Putranjiva roxburghii), Amaltas (Cassia fistula), and Siris (Albizia lebbeck) were carried out by extractive analysis via Soxhlet solvent extraction, compositional analysis, proximate analysis, elemental (CHNSO) analysis, heating value, bulk density, crystallinity index via XRD, functional groups via FTIR, mineral content via EDX, slagging and fouling indices via XRF, and degradation profile via TGA. It was noticed that all seeds consist of a maximum percentage of extractives such as Putranjiva 50.55%, Amaltas 18.22%, and Siris 22.8%. The results showed that these seeds have a higher cellulose content compared with hemicellulose and lignin. Further, it was confirmed from the Van Krevelen diagram, CHO index, as well as devolatilization index. Also, from the kinetic analysis, the activation energy (Ea) obtained of these seeds was in the order of PR > AL > CF. The chemical features and thermal degradation behaviour reaffirmed that these non-edible oilseeds have good energy potential for reproducibility of biofuel and green chemicals production.

Room-temperature extraction of direct coal liquefaction residue by liquefied dimethyl ether

Direct coal liquefaction residue (DCLR) is the main byproduct during the direct coal liquefaction process. The efficient recovery of organic components from DCLR at low temperatures is beneficial for improving the economy and reducing energy consumption and environmental pollution. Here, DCLR was extracted using liquefied dimethyl ether (DME), acetone, and hexane as the solvents. Compared with the other two solvent Soxhlet extraction, the DME extraction process was performed at room temperature with the shortest extraction time, the lowest energy consumption, and the highest extraction yield (16.2%). Owing to the high carbon contents, low sulfur and oxygen contents, and low ash contents (<0.1%), the extracts obtained using liquefied DME and acetone naturally became the feedstock of carbon materials. Based on the results of the gas chromatography-mass spectrometry analysis, the extracts obtained using the three different solvents had similar compositions in light compounds and were abundant in polycyclic aromatic hydrocarbons with two-, three-, four-, five-, and six-membered benzene rings, indicating that all three DCLR extracts are potential raw materials for preparing high value-added carbon materials. Furthermore, the molecular composition analysis revealed that the room-temperature extraction using liquefied DME was as good as high-temperature Soxhlet extraction using acetone, considering the similarity of their compositions in high molecular weight species and the considerably higher efficiency than that of high-temperature Soxhlet extraction using hexane. Due to the low energy consumption, short extraction time, high extraction yield, and high performance of the extract, liquefied DME is an efficient and economic solvent for extracting DCLR.

Antioxidant activity and hepatoprotective effect of &lt;i&gt;Cichorium intybus&lt;/i&gt; (Kasni) seed extract against carbon tetrachloride-induced liver toxicity in rats

Purpose: To assess the antioxidant and hepatoprotective activity of the aqueous-methanol extract of Cichorium intybus seeds (C. intybus) against carbon tetrachloride (CCl4)-induced liver toxicity in albino Wistar rats.Method: The seed extract of C. intybus was prepared in aqueous methanol (20:80) via Soxhlet solvent extraction process. CCl4 (0.8 mL/kg) was administered to induce hepatic damage in Wistar rats. The seed extract (100, 250 and 500 mg/kg doses) and a 25 mg/kg dose of silymarin (as standard drug) were administered orally to separate groups of albino Wistar rats for 14 days. Blood samples from the rats were analyzed for biochemical markers for hepatic injury. The tissue samples of the rats were subjected to histopathological studies as well as analyzed for liver antioxidants.Results: The results for biochemical markers revealed that the rats treated with the extract (500 mg/kg dose) showed a maximum elevation of catalase (48.90 μmole of H2O2 consumed/min/mg protein), glutothione peroxidase (22.1 mg GSH consumed/min/mg protein), superoxide dismutase (14.2 units/min/mg protein), and a reduction in glutathione (18.1 μmole of GSH/mg protein). Serum biochemical parameters including serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), alkaline phosphate (ALKP), and direct bilirubin were significantly (p < 0.01) increased in the treated groups. Oral administration of different doses of C. intybus seed extract significantly (p < 0.01) protected the hepatic cells from impairment. The biochemical markers and hematological parameters were also normal in extract-treated rats in contrast to the standard (silymarin) and control groups.Conclusion: The results show that C. intybus plant is potential a good natural source of natural hepatoprotective and antioxidants agents.Keywords: Cichorium intybus, Antioxidant, Hepatoprotective Biomarkers, Silymarin, Hematological parameters

Effects of Cleaning Treatments on the Surface Composition of Porous Materials

Removal of organic compounds is a common first step in surface characterization of inorganic materials. To explore the surface reactivity of environmental samples such as rocks, soil, and sediments, it is essential to know if they are pure or covered with organic material. Our purpose was to evaluate the influence of some common cleaning procedures on the surface composition of inorganic solids and to investigate if such treatments result in completely clean mineral surfaces. We used Soxhlet solvent extraction and chemical oxidation to remove crude oil from samples that we synthesized to represent oil bearing sandstone. After each cleaning step, we tracked surface composition using X-ray photoelectron spectroscopy. We demonstrated that (i) it was impossible to completely remove the organic material with any of the methods, (ii) the oxidation treatment dissolved soluble minerals, and (iii) surface composition was dominated by clay particles adhering to the larger grains and thus was responsible for a signi...

Contrasting the Pyrolysis Behavior of Selected Biomass and the Effect of Lignin

This study was aimed at comparing the pyrolysis behavior of several selected biomass samples, namely, pine wood, poplar wood, wheat straw, and sugarcane bagasse, with a particular attention to the effect of lignin. Raw samples were first treated using Soxhlet solvent extraction with a 2:1 (v/v) mixture of toluene/ethanol to remove wax. Lignin was then removed by soaking the dewaxed samples in a 1.0 M sodium chlorite solution at 343 K till the solids became white. Fourier transform infrared (FTIR) spectroscopy analysis was applied to characterize the surface functional groups of the samples. The morphology of the samples before and after delignification treatment was analyzed using scanning electron microscope (SEM). The pyrolysis behavior of the raw and treated biomass samples was studied using a thermogravimetric analyzer (TGA) operating in nitrogen at a constant heating rate of 10 K min−1 from room temperature to the final temperature 823 K. The FTIR and SEM results indicated that lignin can be successfully removed from the raw biomass via the chemical treatment used. As expected, the pyrolysis behavior differed significantly among the various raw biomass samples. However, the pyrolysis behavior of the delignified samples showed almost identical thermal behavior although the temperature associated with the maximum rate of pyrolysis was shifted to a lower temperature regime by ca. 50 K. This suggests that the presence of lignin significantly affected the biomass pyrolysis behavior. Thus, the pyrolysis behavior of the biomass cannot be predicted simply from the individual components without considering their interactions.

Extraction of phytocompounds from the medicinal plant Clinacanthus nutans Lindau by microwave-assisted extraction and supercritical carbon dioxide extraction

The composition and bioactivity of natural plant extracts strongly depends on the extraction technique employed. Clinacanthus nutans Lindau (C. nutans) is a well-known medicinal plant in South-East Asia that has been traditionally used for treatment of hepatitis, skin-rashes and snake venom poisoning, and recently has attracted attention for its applications for treatment and prevention of cancer diseases. In previous studies, the extraction of bioactive compounds from C. nutans by conventional Soxhlet solvent extraction has been described, but this method shows limitations in terms of selectivity, extraction yield and toxicity of the solvents employed. In this study, phytochemical compounds were extracted from leaves and stems of C. nutans by microwave-assisted extraction (MAE), pressurized microwave-assisted extraction (PMAE), supercritical carbon dioxide extraction (SFE) and Soxhlet method to investigate the best technique in terms of yield, extraction time and recovery of bioactive compounds: phenols, flavonoids, phytosterols and β-sitosterol. The extracted phytocompounds and phenolics were characterized by gas chromatography mass spectrometry (GC/MS) and ultra performance liquid chromatography (UPLC). The results showed that MAE was the best technique to achieve a high yield and a maximal total polyphenol content (11.30±0.39mg GAE/g DM) and flavonoids content (and 4.66±0.20mg GAE/g DM), whereas SFE was the best method for phytosterols and β-Sitosterol extraction. P-MAE merely enhanced the polyphenol and flavonoids yield to 14.56±0.77mgGAE/g DM and 5.29±0.30mg QE/g DM respectively, without significant variations on the type of compounds obtained. MAE appears as the most efficient technique for the extraction of phytochemical compounds from C. nutans in a short time with a reasonable yield and a good selectivity toward bioactive nutraceutical compounds, with high concentrations of antioxidants, anti-inflammatory and antimicrobial compounds.

Supercritical carbon dioxide extraction of petroleum on kieselguhr

Carbon dioxide-based supercritical fluid extraction (CO2 SFE) has been an excellent alternative to solvent extraction in many industries. In this study, a heavy crude oil was adsorbed to kieselguhr and performed for comparison of different extraction processes. The oil extract by dichloromethane Soxhlet extraction was used as a benchmark. Another batch of the sample was subjected to sequential short-time and longer-time CO2 SFE, and subsequent dichloromethane Soxhlet extraction, yielding three distinct extracts. All of these four extracts were then fractionated by a standard saturates/aromatics/resin/asphaltene (SARA) method. Each SARA fraction was then analyzed by high temperature gas chromatography simulated distillation (SIMDIS), gas chromatography–mass spectrometry (GC–MS) and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). It was found that CO2 SFE selectively extracts relatively low molecular weight compounds with low degrees of molecular condensation. The remaining un-extracted components are mainly in polar resin and asphaltene fractions, containing the chemical species with large carbon numbers and high degrees of molecular condensation. Most of these components are in low volatility with boiling points higher than 500°C, beyond the upper temperature limit of common GC columns. CO2 SFE can serve as an environmental-friendly alternative to Soxhlet solvent extraction if the goal of the analysis is to determine petroleum biomarker or compositional analysis by GC–MS. In addition, CO2 SFE for extracts only volatile compounds of small molecular weight has an advantage of leaving most non-volatile components that would be detrimental to the GC systems.

Effect of Feeding Frequency on Body Composition of Rainbow Trout ( Oncorhynchus mykiss -Walbaum, 1792) Fingerlings

A 21-days experimental trial was conducted to examine the influence of feeding frequency on body composition of rainbow trout fingerlings. A number of 295 trout fingerlings (with mean initial weight ±SD of 5.53±0.25g), from Cislau fish farm, Buzau city, were equally stocked in four rearing units. The two experimental variants ( feeding frequency 2 meals/day -F1 and 4 meals/day -F2) were each applied for two tanks. At the end of the experiment, fish meat biochemical composition was significantly influenced (p<0.05) by feeding fr equency. Keywords: rainbow trout, meat biochemical composition, aquaculture recirculating systems Introduction. Optimum feeding frequency, for maximum fish growth may vary according to fish species, size and culture conditi ons, including feed quality, amount of feed administrated and water temperature values throughout the experimental trial (Lee et al., 2000). One of the factors that lead to choose an ap propriate feeding frequency consists in determining the time between meals, because feed consumption is closely related to stomach capacity, gastric emptying rate and digestion (Bret t, 1971; Riche et al, 2004). A feeding frequency between 1-3 meals/day is reported to be p roper for rainbow trout. Aims and Objectives. Knowing the fact that biochemical composition of meat is influenced by several factors such as fish size, ag e, environmental and feeding conditions, the present study was conducted to determine the influe nce of feeding frequency on growth and body composition of rainbow trout fingerlings, in c onditions of using different feeding frequencies. Materials and Methods. The experiment was carried out between October 25 and November 16, 2010 at the pilot recirculating system of Aquaculture, Environmental Science and Cadastre Department from Dunarea de Jos University of Galati. The experimental system consisted of 4 four growing units with a tot al volume of 0.336 m 3 (0.35◊0.80◊0.120m) each and water quality maintenance module, represented by water mechanical and biological filtration units, water sterilization unit (represe nted by a UV lamp) and water oxygenation unit and 295 trout fingerlings. The two treatments (feed ing frequency of 2 meals/day -F1 and 4 meals/day -F2) were each applied for two tanks. On the first six days of experiment, fish were fed with a ratio of 3%/BW/day and then, the ratio i ncreased up to 5% on the eighth day; after that the ratio remained constant till the end of th e trial. The rainbow trout meat biochemical determinations were performed on muscle tissue samples and later, from the mixture, homogeneous samples were taken. Proteins were determined with Gerhardt type equipment by using Kjeldahl method, fats were determined by Soxhlet solvent extraction method (petroleum ether) with Raypa extraction equipment, dry matter was determined by heating at temperature of 105 ±2oC using Sterilizer Esac and a sh was evaluated by calcification at temperatures of 550±20°C in a Nabertherm furnace. Results and Discussions. The results regarding the biochemical composition of rainbow trout meat, fed under different feeding fre quencies conditions are presented in Fig. 1 . After statistical analysis were made, significant d ifferences (p<0.05) were registered for all

LDPE 중 PFOS의 분석법 개발과 비교숙련도 결과

전기전자 부품 및 제품상에서 주로 사용되는 Plastic 중 함유된 Perfluorooctanesulfonic acid (PFOS)의 정량 분석법을 개발하기 위해 LDPE 시료를 대상으로 soxhlet 용매추출과 액체크로마토그래피/질량분석법(LC/MS)을 사용하여 시험방법 유효화를 진행하였다. 그 결과 검출한계(LOD)와 정량한계(LOQ)는 각각 <TEX>$2.58{\mu}g/L$</TEX>, <TEX>$7.82{\mu}g/L$</TEX>였으며, 회수율은 96-102%를 나타내었다. LC/MS의 검량선은 <TEX>$7.82-100{\mu}g/L$</TEX> 농도범위에서 <TEX>$r^2$</TEX>값 0.9992의 직선성을 확인하였다. 또한 EU 환경규제 대응을 위한 전기전자 제품 중의 PFOS 분석법 표준화를 위해서 국내외 시험기관을 대상으로 비교숙련도 시험을 실시하였다. 그 결과 참여한 10개 시험기관 중 3개 시험기관이 이상값을 제출하였다. 이에 <TEX>$^{19}F$</TEX> 핵자기공명분광분석법(<TEX>$^{19}F$</TEX> NMR)을 사용하여 이상값의 원인을 규명한 결과 그 주요 원인이 표준시약 및 시료 중에 존재하는 PFOS 이성질체들에 대한 결과처리의 오류였음을 확인하였다. In order to develop a quantitation method for Perfluorooctanesulfonic acid(PFOS) contained in plastics that are mainly used in electric and electronic equipment, this study consisted of conducting method validations with LDPE samples using soxhlet solvent extraction and LC/MS. As a result, the limits of detection and quantitation (LOD, LOQ) were <TEX>$2.58{\mu}g/L$</TEX> and <TEX>$7.82{\mu}g/L$</TEX>, respectively. Additionally, the recovery was 96-102%. For the correlation coefficient of LC/MS, the <TEX>$r^2$</TEX> value was 0.9992 in the concentration range of <TEX>$7.82-100{\mu}g/L$</TEX>, which confirmed its linearity. Furthermore, for the standardization of the analysis method for PFOS in electric and electronic equipment to correspond to EU environmental regulations, we conducted a proficiency test with a number of domestic and international testing laboratories. Three of the ten testing laboratories that participated in the proficiency test submitted outliers. Accordingly, we examined the cause of the outliers using the <TEX>$^{19}F$</TEX> NMR, finding that the main cause was an error in the processing of the results for isomers in PFOS that existed in standard solutions and samples.

Low Molecular Weight Compounds Contained in Coal and the Behaviors of Methane Adsorbed by Coal at Isothermal High-Pressure Condition

Coal seam mehtane deposit at depth has been paid attention to. With the theory of coal structure, techniques of isothermal high-pressure adsorption and the method of Soxhlet solvent extraction, the behaviors of methane adsorbed by coal sample and its residuals were studied. At the condition of the isothermal and high methane pressure, the results of adsorption experiment show that when the methane pressure is continuously increased, the capability of methane absorbed by Pingdingshan fat coal sample gradually increases, reach to a maximum, then decrease, this phenomenon do not accord with the Langmuir’s model, but the capability of methane absorbed by Jiaozuo anthracite sample and Pingdingshan fat coal’s residuals with tetrahydrofuran gradually increase to a fixed value, and is not changed any longer. Solvent extraction of coal indicate that low molecular weight compounds contained in coal have three modes of occurrence, including free, absorbent and co-soluble mode. We can infer to conclusion: (1) low molecular weight compounds contained in coal affect greatly on the behaviors of methane adsorbed by coal at isothermal high-pressure condition, (2) low molecular weight compounds contained in fat coal is high in content, and the free mode of them are forced to remove and displace the potential space of methane molecule occupancy, the capability of methane absorbed by coal is reduced at condition of methane pressure above certain value. And it is concluded that at fat coal rank, methane content gradually increases, reach to a maximum, then decrease, but at rank of the anthracite, it gradually increases to a fixed value, and is not changed any longer with the increase of buried deepness and confining pressure in coal seam.