Studies of biodegradability of certain oils in forest soil as determined by the respirometric BOD OxiTop method

The suitability of the respirometric BOD OxiTop method for biodegradation studies of different oils in soil was assessed. Different forestry chain oils and wood-preservative oils were used as model substances. Experiments were carried out on different types of Finnish forest soils. The results of these experiments are in good agreement with our earlier results of oil-biodegradation experiments in water. The BOD OxiTop method proved to be a highly suitable analysis method for biodegradation studies of oils in soil.     

测压法测定水中BOD的方法研究

对测压法（连续耗氧量一呼吸计量法）测定水中BOD的方法进行了研究。分别用测压法和传统方法测定了标准溶液和实际样品的BOD值,结果表明,测压法测定BOD具有生化效率高、操作简单、测试方便的优点,可连续测定BOD值并储存测量数据。测压法测定的BOD值更能表征水体可生化降解性,与传统法的测定结果有较好的可比性。     

Native biofilm cultured under controllable condition and used in mediated method for BOD measurement

In this article, we developed a native biofilm (NBF) bioreactor used for biochemical oxygen demand mediated method (BOD_Med). There were two innovations differed from previous BOD_Med assay. Firstly, the immobilization of microorganisms was adopted in BOD_Med. Secondly, the NBF was introduced for BOD measurement. The NBF bioreactor has been characterized by optical microscopy. A culture condition of NBF with 24 h, 35 °C and pH 7 was optimized. Furthermore, a measuring condition with 35 °C, pH 7 and 55 mM ferricyanide in 1 h incubation were optimized. Based on the optimized condition, the real wastewater samples from local sewage treatment plant had been measured. Performances of the NBFs proposed at different culture conditions were recorded for 110 d, and the results indicated that long-term storage stability was obtained. With the proposed method, an uncontaminated native microbial source solution can be obtained from a wastewater treatment plant. In this way, we can ensure that the microbial species of all in the NBF are same as that in the target to be measured.     

Ab initio SCF calculations of the linear infinite chain of LiH according to the pseudo-lattice method

The pseudo-lattice (PL) method has been reformulated for ab initio self-consistent-field (SCF) calculations. The translational symmetries of infinite systems have been applied to the finite model chain by manipulating all the intramolecular and intermolecular Fock matrices. The nuclear repulsion energy has been corrected accordingly. The method has been tested for the linear chain of lithium hydride under the constraint of equidistance between all neighboring lithium and hydrogen atoms. The calculated results of the infinite chain have been compared with those of finite chains of lithium hydride under the same geometric constraint. The equilibrium geometries, band structures, intermolecular stabilization energies and potential curves have been studied. It is found that the infinite systems cannot be described by considering only first nearest neighbor interactions, and the intermolecular interactions must be considered at least up to third nearest neighbors in order to obtain accurate value of force constant of infinite systems. We can conclude from band structures of infinite chains that the boundary effect of the finite model chain is effectively removed by the PL method.     

Optical biosensor for the determination of BOD in seawater

An automatic sensing system was developed using an optical BOD sensing film. The sensing film consists of an organically modified silicate (ORMOSIL) film embedded with an oxygen-sensitive Ru complex. A multi-microorganisms immobilization method was developed for the BOD sensing film preparation. Three different kinds of microorganisms, Bacillus licheniformis, Dietzia maris and Marinobacter marinus from seawater, were immobilized on a polyvinyl alcohol ORMOSILs. After preconditioning, the BOD biosensor could steadily perform well up to 10 months. The linear fluctuant coefficients (R²) in the range of 0.3-40 mg L⁻¹ was 0.985 when a glucose/glutamate BOD standard was applied. The reproducible response for the BOD sensing film could be obtained within ±2.3% of the mean value in a series of 10 samples in 5.0 mg L⁻¹ BOD standard GGA solution. The effects of temperature, pH and sodium chloride concentration on the two microbial films were studied as well. The BOD sensing system was tested and applied for the BOD determination of seawater.     

Quantitative determination of toluene,ethylbenzene, and xylene degradation products in contaminated groundwater by solid-phase extraction and in-vial derivatization

Benzylsuccinic acid (BSA) and methylbenzylsuccinic acids (mBSAs) are unambiguous indicators of anaerobic toluene and ethylbenzene/xylene degradation, and so the determination of these compounds in landfill leachates and contaminated groundwater is highly relevant. Samples were diluted to <0.8?mS?cm^?1 in order to reduce their ionic strength, and subsequently extracted through strong anion exchange disks, followed by simultaneous in-vial elution and methylation. A detection limit of 0.1?µg?L^?1 was obtained for 100?mL samples. Using this method, 19.3?µg?L^?1 of BSA was measured in a landfill leachate, and low µg?L^?1 levels of all of the mBSAs were measured in gasoline-contaminated groundwater. The results were compared with the findings of BSAs at 16 other contaminated sites, and BSAs as indicators of biodegradation were evaluated. The estimation of biodegradation rates based on parent hydrocarbons and BSA concentrations or ratios is questionable. However, the degradation products serve as good qualitative in situ indicators for anaerobic biodegradation in contaminated groundwater.     

A new BOD estimation method employing a double-mediator system by ferricyanide and menadione using the eukaryote Saccharomyces cerevisiae

A new biochemical oxygen demand (BOD) sensing method employing a double-mediator (DM) system coupled with ferricyanide and a lipophilic mediator, menadione and the eukaryote Saccharomyces cerevisiae has been developed. In this study, a stirred micro-batch-type microbial sensor with a 560 μL volume and a two-electrode system was used. The chronamperometric response of this sensor had a linear response between 1 μM and 10 mM hexacyanoferrate(II) (r² = 0.9995, 14 points, n = 3, average of relative standard deviation and R.S.D._av = 1.3%). Next, the optimum conditions for BOD estimation by the DM system (BOD_DM) were investigated and the findings revealed that the concentration of ethanol, used to dissolve menadione, influenced the sensor response and a relationship between the sensor output and glucose glutamic acid concentration was obtained over a range of 6.6-220 mg O₂ L⁻¹ (five points, n = 3, R.S.D._av 6.6%) when using a reaction mixture incubated for 15 min. Subsequently, the characterization of this sensor was studied. The sensor responses to 14 pure organic substances were compared with the conventional BOD₅ method and other biosensor methods. Similar results with the BOD biosensor system using Trichosporon cutaneum were obtained. In addition, the influence of chloride ion, artificial seawater and heavy metal ions on the sensor response was investigated. A slight influence of 20.0 g L⁻¹ chloride ion and artificial seawater (18.4 g L⁻¹ Cl⁻) was observed. Thus, the possibility of BOD determination for seawater was suggested in this study. In addition, no influence of the heavy metal ions (1.0 mg L⁻¹ Fe³⁺, Cu²⁺, Mn²⁺, Cr³⁺ and Zn²⁺) was observed. Real sample measurements using both river water and seawater were performed and compared with those obtained from the BOD₅ method. Finally, stable responses were obtained for 14 days when the yeast suspension was stored at 4 °C (response reduction, 93%; R.S.D. for 6 testing days, 9.1%).     

Comparison of microbial activity in some Brazilian soils by microcalorimetric and respirometric methods

The microbial activity in a Rhodic eutrudox (R), a Typic eutrudox (V) and a Quartzipsamment (Q) was monitored by respirometric and calorimetric methods. CO₂ evolution was monitored for 98 days by titrimetry and conductimetry for control amended samples (A) with 25% of cattle manure (E), municipal refuse compost (L), earthworm casts (H) or 1.25 kg ha⁻¹ of trifluralin (T). Average values of all treatments through respiration at the end of the incubation period were 5.24±0.34, 6.13±0.31 and 6.50±0.33, in mg CO₂ g⁻¹ soil, for R, V and Q, respectively, by titrimetry and 8.89±0.44, 10.41±0.54 and 10.41±0.52, in mg CO₂ g⁻¹ soil, for R, V and Q, respectively, for conductimetry. Excellent correlation (r=1.00) between titrimetry and conductimetry was observed. The decreasing order for respiration was E, H, L and T. After each incubation time, the conductimetric values were higher than those for titrimetry, for all treatments of these Brazilian soils. Average values of the exothermic thermal effect were: 0.58±0.02, 0.60±0.02 and 0.67±0.01 kJ g⁻¹ soil, for R, V and Q, respectively, for 103 days. A significant correlation coefficient of 0.91 and P<0.0001 between calorimetric and respirometric values over 98 days was observed. Based on the obtained calorimetric results, it can be proposed that this technique should be as a useful analytical method for determining the microbial activity in soils.     

微波辐射法提取柚皮、橙皮的挥发油

The essence oil of citrus grandis peel and orange peel was extracted by the microwave method in this article.The results show that the best condition of extracting is when 100 g peel is extracted at 360 W with n-hexane for 50 s,the obtained rate of pomelo oil is 1.73% and orange oil is 0.65%.     

Effect of chain structure on ductile–brittle transition in some polyestercarbonates

The relation between chain structure and ductile–brittle transition (DBT) in polyestercarbonates (PEC) was investigated by measuring the fracture energy and observing the fracture surfaces of a homologous series of PEC containing phthalate units. DBTs were determined in terms of various test conditions including specimen thickness, test speed, and notch-tip radius. With an increase in the phthalate content, transition was found to shift to a thinner specimen, a lower test speed, and a higher notch-tip radius. It was concluded that the DBT is directly affected by the extent of entanglement in these copolymers.     

Determination of betaines in vegetable oils by capillary electrophoresis tandem mass spectrometry--application to the detection of olive oil adulteration with seed oils

A CE–tandem mass spectrometry (MS²) methodology enabling the simultaneous determination of betaines (glycine betaine, trigonelline, proline betaine and total content of carnitines) in vegetable oils was developed. Betaines were derivatized with butanol previous to their baseline separation in 10 min using a 0.1 M formic acid buffer at pH 2.0. Ion trap conditions were optimized in order to maximize the selectivity and sensitivity. Analytical characteristics of the proposed method were established by evaluating its selectivity, linearity, precision (RSDs ranged from 4.8 to 10.7% for corrected peak areas) and accuracy by means of recovery studies (from 80 to 99%) and LODs and LOQs at 0.1 ppb level. The method was applied for the determination of the selected betaines in seed oils and extra virgin olive oils. MS² experiments provided the fingerprint fragmentation for the betaines identified in vegetable oils. In extra virgin olive oils, carnitines were not detected, making it possible to propose them as a feasible novel marker for the detection of adulterations of olive oils. Application of the developed method for the analysis of different mixtures of extra virgin olive oil with seed oil (between 2 and 10%) enabled the detection and quantitation of the total content of carnitines. The results obtained show the high potential of the developed method for the authentication and quality control of olive oils.     

The influence of chain rigidity on the thermal properties of some novel random copolyethersulfones

Some random low molar mass (M_n ≈ 9000 g mol⁻¹) poly(ethersulfoneethersulfone)/poly(ethersulfoneethersulfonebiphenylsulfone) P(ESES)/P(ESESBS) copolymers, with various (25%, 50% and 75%) ESESBS units contents, were synthesized to obtain compounds with higher chain rigidity than PES. The thermal characterization of the prepared copolymers, as well as that of corresponding P(ESES) and P(ESESBS) homopolymers, was performed, and all investigated parameters showed strong dependence on polymer composition.The glass transition temperature (T_g) was calorimetrically determined by DSC technique, and the obtained values increased linearly as function of ESESBS units percentage, thus indicating an increasing chain rigidity.Degradations were carried out in dynamic heating conditions, from 35 °C to 700 °C, in both flowing nitrogen and static air atmosphere, and the characteristic parameters of degradation were determined in order to draw useful information about the overall thermal stability of the studied compounds. The apparent activation energy of degradation (E_a) was obtained by the Kissinger method, and the values found increased linearly as a function of ESESBS content, while the temperature values at 5% mass loss (T_5%) showed an opposite linear trend. The results are discussed and interpreted.     

雄县地下水多组分含量分析及水质评价

为了解雄县地区地下水水化学特征及水质现状,选取43组地下水,采用仪器分析和容量法相结合的方式对雄县地下水典型的环境项目进行测定,运用数理统计和三元相图分析了雄县地下水的主要离子特征,并运用综合评价法对地下水质量予以评价。结果表明,该类指标的方法检出限为0.001～1.30mg/L,相对标准偏差为0.30%～3.7%,pH值和偏硅酸空间变异最低(CV30%),Mg~(2+)、Cl~-、SO_4~(2-)和碘化物的空间变异性最高(CV100%),水化学类型主要以HCO_3-Na型为主,水质评价结果显示研究区域地下水水质总体状况较好,多为Ⅱ类水和Ⅲ类水。研究成果对了解雄县地下水水质现状具有重要意义。     

Isotopes in groundwater as indicators of climate changes

Isotopes of the water molecule (δ¹⁸O and δ²H) are a well-used tool for investigating groundwater origin and history (i.e. tracing the recharge conditions over time, processes occurring during infiltration of rainwater towards aquifers and those involved in the water-rock interaction, and mixing of different waters).This review covers several large European aquifers (Portugal, France, UK, Switzerland, Germany, Hungary, and Poland), which were investigated in terms of their recharge conditions, and the story of the groundwater at a large scale, involving recent, Holocene and Pleistocene components and their eventual mixing.     

Development of a simple method for the determination of nitrite and nitrate in groundwater by high-resolution continuum source electrothermal molecular absorption spectrometry

In this work, it was developed a method for the determination of nitrite and nitrate in groundwater by high-resolution continuum source electrothermal molecular absorption spectrometry of NO produced by thermal decomposition of nitrate in a graphite furnace. The NO line at 215.360 nm was used for all analytical measurements and the signal obtained by integrated absorbance of three pixels. A volume of 20 μL of standard solution or groundwater sample was injected into graphite furnace and 5 μL of a 1% (m/v) Ca solution was co-injected as chemical modifier. The pyrolisis and vaporization temperatures established were of 150 and 1300 °C, respectively. Under these conditions, it was observed a difference of thermal stability among the two nitrogen species in the presence of hydrochloric acid co-injected. While that the nitrite signal was totally suppressed, nitrate signal remained nearly stable. This way, nitrogen can be quantified only as nitrate. The addition of hydrogen peroxide provided the oxidation of nitrite to nitrate, which allowed the total quantification of the species and nitrite obtained by difference. A volume of 5 μL of 0.3% (v/v) hydrochloric acid was co-injected for the elimination of nitrite, whereas that hydrogen peroxide in the concentration of 0.75% (v/v) was added to samples or standards for the oxidation of nitrite to nitrate. Analytical curve was established using standard solution of nitrate. The method described has limits of detection and quantification of 0.10 and 0.33 μg mL⁻¹ of nitrogen, respectively. The precision, estimated as relative standard deviation (RSD), was of 7.5 and 3.8% (n = 10) for groundwater samples containing nitrate–N concentrations of 1.9 and 15.2 μg mL⁻¹, respectively. The proposed method was applied to the analysis of 10 groundwater samples and the results were compared with those obtained by ion chromatography method. In all samples analyzed, the concentration of nitrite–N was always below of the limit of quantification of both the methods. The concentrations of nitrate–N varied from 0.58 to 15.5 μg mL⁻¹. No significant difference it was observed between the results obtained by both methods for nitrate–N, at the 95% confidence level.     

Development and validation of a solid-phase microextraction method for the analysis of volatile organic compounds in groundwater samples

Summary Solid-phase microextraction is a relatively recent extraction technique for sample preparation. It has been used successfully to analyse environmental pollutants in a variety of matrices such as soils, water and air. In this work, a simple and rapid method for the analysis of volatile organic and polar compounds from polluted groundwater samples by SPME coupled with gas chromatography (GC) is described. Different types of fibres were studied and the extraction process was optimised. The fibre that proved to be the best to analyse this kind of samples was CAR-PDMS. The method was validated by analysis of synthetic samples and comparison with headspace—GC. The optimised method was successfully applied to the analysis of ground-water samples.     

A novel approach to the rapid assignment of 13C NMR spectra of major components of vegetable oils such as avocado,mango kernel and macadamia nut oils

Assignment of ¹³C nuclear magnetic resonance (NMR) spectra of major fatty acid components of South African produced vegetable oils was attempted using a method in which the vegetable oil was spiked with a standard triacylglycerol. This proved to be inadequate and therefore a new rapid and potentially generic graphical linear correlation method is proposed for assignment of the ¹³C NMR spectra of major fatty acid components of apricot kernel, avocado pear, grapeseed, macadamia nut, mango kernel and marula vegetable oils. In this graphical correlation method, chemical shifts of fatty acids present in a known standard triacylglycerol is plotted against the corresponding chemical shifts of fatty acids present in the vegetable oils. This new approach (under carefully defined conditions and concentrations) was found especially useful for spectrally crowded regions where significant peak overlap occurs and was validated with the well‐known ¹³C NMR spectrum of olive oil which has been extensively reported in the literature. In this way, a full assignment of the ¹³C{1H} NMR spectra of the vegetable oils, as well as tripalmitolein was readily achieved and the resonances belonging to the palmitoleic acid component of the triacylglycerols in the case of macadamia nut and avocado pear oil resonances were also assigned for the first time in the ¹³C NMR spectra of these oils. Copyright © 2009 John Wiley & Sons, Ltd.     

Low temperature purification method for the determination of abamectin and ivermectin in edible oils by liquid chromatographytandem mass spectrometry

In this study,a method based on low temperature purification(LTP) coupled with liquid chromatography-tandem mass spectrometry(LC-MS/MS) was developed for the determination of abamectin(ABA) and ivermectin(IVR) in edible oils.ABA and IVR were extracted using conventional liquid-liquid extraction followed by purification via precipitation of interfering fatty components at low temperature without an additional cleanup step.LTP is simple,easy to use,labour-saving and cost effective,and requires reduced amounts of organic solvent.The linear ranges of ABA and IVR were 5-1000 μg/L using matrix-matched standards.Limits of detection(LOD) and limits of quantification(LOQ)were in the range of 0.1-0.4 μg/kg and 0.3-1.3 μg/kg,respectively.The LOQs were below the strictest maximum residue limits established by Codex Alimentarius Commission.Recoveries at three spiked levels of 10,20 and 100 μg/kg in peanut oil,corn oil,olive oil,soybean oil and lard ranged from 71.1%to119.3%with relative standard deviations of 3.2%-10.3%,which were in agreement with those obtained by the solid phase extraction method.The proposed method was utilized in the analysis of 10 edible oil samples from local market and neither ABA nor IVR was detected.As far as we know,this is the first time that LTP is applied to the determination of avermectins in edible oils.     

Determination of carbetamide in groundwater by micro liquid-liquid extraction and gas chromatography-mass spectrometry

Summary A method is proposed for the determination of carbetamide in water below European Union guidelines (detection limit,DL, below 0.1 μgL⁻¹). Micro liquid-liquid extraction with dichloromethane affords carbetamide which is converted to aniline by hydrolysis. Identification and quantification of aniline was performed by GC-MS. The retention time was 4.24 min. Quantification was achieved by single-ion monitoring (SIM) atm/z 66 and 93. Clean-up is not necessary before SIM. Deuterated anthracene (²H₁₀-anthracene) was used as internal standard. The method was used to determine carbetamide in different types of water sample spiked at very low concentration levels (0.13–10.00 μgL⁻¹). TheDL was 0.04 μgL⁻¹. The effect of the presence of other carbamates was also studied.