基体分离/MC-ICP-MS测定树皮表层235U/238U同位素比率

分别从日本广岛和京都采集了香樟树(Cinnamomum camphora)树皮样品共12份,用X射线能谱仪研究了树皮表层基体元素组成,并用扫描电镜观察了树皮表层微观形貌.将树皮表层样品进行干灰化法处理后,采用DOWEX(R)1-X8型阴离子交换树脂分离基体元素,然后用多接收器电感耦合等离子体质谱仪(MC-ICP-MS)测定了树皮表层235U/238U同位素比率.研究结果表明:树皮表层主要基体元素为Al,Ca,Fe,K,Mg,Si和C,O,S;采用不同浓度硝酸淋洗DOWEX(R) 1-X8型阴离子交换树脂可实现树皮表层痕量U与基体元素的有效分离.与京都树皮表层相比,广岛树皮表层不仅U含量显著偏高(P=0.012),而且部分样品235U/238U同位素比率亦略高于其自然丰度比.     

中性红褪色光度法测定蒙药铜灰体系中产生的过氧化氢含量

在 p H=3.5的乙酸 -乙酸钠缓冲溶液中 ,用中性红褪色光度法测定了蒙药铜灰体系中产生的过氧化氢的含量。过氧化氢在 0— 5 0μg/ 2 5 m L范围内与 lg(A0 / A)值呈线性关系 ,线性回归方程为 lg(A0 / A) =2 .5× 10 -3+1.0 5× 10 -2 C双氧水 (μg/ 2 5 m L) ,r=0 .9999     

Mineral content and physical properties of local and imported honeys in Saudi Arabia

In addition to color, ash and electrical conductivity (EC), the levels of 14 minerals were investigated in 23 varieties of honey from Saudi Arabia and six other countries. The quantities of the macrominerals obtained were as follows (in ppm): K (298.60–491.40), Mg (80.70–199.30), Ca (60.75–99.95), P (21.10–33.29), and Na (15.69–26.93). The quantities of trace minerals were as follows (in ppm): Fe (67.18–98.13), I (12.61–94.68), Mn (4.15–6.04), Zn (3.44–5.72), Li (1.15–4.26), Co (1.00–1.32), and Ni (0.15–0.67). The quantities of the heavy metals Pb and Cd were found to be 0.06–0.23 and 0.00–0.16, respectively. The values of the tested elements—color, ash and EC—varied among the tested honeys according to their botanical origin. Dark honeys, especially acacia honeys, had higher elemental content and EC values than lighter ones. Saudi and Yemeni seder honeys exhibited no distinctive characteristics in their tested parameters. The levels of heavy metals indicated that the tested honeys were safe for human consumption.     

Residue analysis and kinetics modeling of thiophanate-methyl,carbendazim, tebuconazole and pyraclostrobin in apple tree bark using QuEChERS/HPLC–VWD

Winter is the key period for the control of apple diseases, and fungicides are needed to protect the trunk or main branches. Fungicide residue in apple tree bark is an important basis for the action of the pesticide, but there are no reports on analytical methods or dissipation patterns. In this work, thiophanate-methyl, carbendazim, tebuconazole and pyraclostrobin were selected as typical fungicides and a new QuEChERS–HPLC–VWD(QuEChERS extraction followed by high-performance liquid chromatography detection with a variable wavelength detector) analytical method was developed to estimate their residue kinetics in apple tree bark during the winter months. In the pretreatment step, the sorbent for the clean-up of extracts was optimized as 60 mg/ml primary secondary amine and a gradient-elution model followed by a variable wavelength detection was developed for instrumental analysis. Then this method was validated and applied to the analysis of apple tree bark samples with the linearity range of 0.010–50.00 mg/L, quantification limit range of 0.028–0.080 mg/kg and recovery range of 86.1–101.4%. The dissipation kinetics of thiophanate-methyl and pyraclostrobin could be described by the first-order and two-phase kinetics models, respectively. For carbendazim and tebuconazole, two new models were developed to describe their residue kinetics.     

两种树皮热解微晶结构及生物油组分对比

以针叶材杉木树皮和阔叶材桉木树皮为原料,利用X射线衍射 (XRD) 对两种树皮热解前后固体颗粒微晶结构的变化进行了比较,利用气质联用 (GC-MS)、凝胶渗透色谱 (GPC) 等手段对两种树皮生物油组分进行了对比分析。结果表明,两种树皮中的纤维结构及脂肪链结构在热解过程中发生了分解,基本被破坏。杉木树皮和桉木树皮生物油主要组分相似,含有酸类、酮类、酚类、醇类、醛类、糖类、酯类等类物质,但相对含量存在差异;桉木树皮相对杉木树皮热解生成了较多的酸类、酮类物质,而酚类、醇类、糖类物质相对较少。两种树皮生物油中酚类物质占有较大的比例,以苯酚和邻苯二酚为主。两种树皮生物油主要物质分子量集中在300~500 g/mol,但桉木树皮生物油中分子量在300~500 g/mol的相对含量 (48.18%) 相比杉木树皮 (61.14%) 较少。     

Leaching Studies of Inorganic and Organic Compounds from Fly Ash

Fly ash is produced in massive quantities by fossil fuel based power plants and waste incinerators, and contains high levels of potentially toxic chemicals. Various leaching tests exist to determine the available fractions, but the outcome is strongly dependent on the experimental conditions, and these have not yet been harmonised at the international level. In order to test existing protocols for heavy metals, several intercomparisons were organised within the framework of an EU-INCO project "ANALEACH", in which seven institutes from five countries participated. Two existing reference materials were made available for the project and test batches of two new fly ash reference materials were produced. Availability tests, leaching tests and pH-stat tests were studied and critical steps in the procedures were identified. Fly ashes can also contain large amounts of inorganic sulphur and nitrogen compounds, and the determination and leaching behaviour of these compounds were also studied. In one intercomparison for metals, inorganic S and N-compounds were also included. A five-step leaching test was optimised for fly ash in order to link metal fractions to different types of binding. Column leaching experiments were carried out to investigate leaching from fly ash into soil, mimicking the effects of (acid) rain on fly ash deposited on topsoil after atmospheric transport. The major fraction of the leached metal ions was retained by the soil. Also large numbers of organic compounds (including many toxic ones) were identified in fly ash extracts, especially in city waste incinerator ash. Leaching procedures based on ultrasonic extraction were developed for organic compounds and an intercomparison exercise was organised. In a field study at the river Nitra(Slovakia) numerous organic pollutants were found at elevated levels downstream from a major fly ash dump site.     

Sequential extraction partitioning of metals,sulfur, and phosphorus in bottom ash from a coal-fired power plant

Abstract

The herbicide trifluralin was analysed by adsorptive stripping voltammetry on a glassy carbon electrode. The linear concentration range was 2.5 × 10^?7 M – 1.25 × 10^?6M when using 5-min preconcentration at open circuit conditions in Britton-Robinson buffer of pH 7.0. The detection limit of trifluralin was 2.5 × 10^?8M. The relative standard deviation was 3.3% at a concentration of 1.0 × 10^?6M (n=5). The method was applied to the determination of trifluralin in soil with good recovery.     

Determination of Cu(II), Fe(III), Mn(II) and Zn(II) in various samples after preconcentration with Rhizopus oryzae loaded natural cellulose (almond bark)

A procedure for the pre-concentration of Cu(II), Fe(III), Mn(II) and Zn(II) is described utilising a minicolumn of natural cellulose (almond bark) modified with fungus (Rhizopus oryzae) prior to their determination by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). The optimum pre-concentration conditions such as pH and flow rate for the analytes have been investigated. The analytes were quantitatively retained on the column between pH 6 and 8. Elution was made with 10 mL 1 M HCl solution. Under the optimum conditions, recoveries were found as 97 ± 3%, 96 ± 3%, 98 ± 3% and 94 ± 2% for Cu(II), Fe(III), Mn(II) and Zn(II), respectively, at 95% confidence level. The detection limits obtained from preconcentration of 50 mL of blank solutions (n = 11) were 1.6, 1.8, 2.8 and 1.2 µg L^?1 for Cu(II), Fe(III), Mn(II) and Zn(II), respectively. Relative standard deviations (RSD) of the recoveries for five replicate analyses were lower than 3%. The proposed method was validated by analysing certified reference materials (Peach Leaves SRM 1547 and Fish Tissue IAEA-407). Determination of the Cu(II), Fe(III), Mn(II) and Zn(II) in K?z?l?rmak River water, green beans, beans leave and tomato leaves and fish (Tinca tinca) tissue samples was performed by the proposed method.     

Dynamics of Phloridzin and Related Compounds in Four Cultivars of Apple Trees during the Vegetation Period

Apple trees (Malus domestica Borgh) are a rich source of dihydrochalcones, phenolic acids and flavonoids. Considering the increasing demand for these phytochemicals with health-benefitting properties, the objective of this study was to evaluate the profile of the main bioactive compounds—phloridzin, phloretin, chlorogenic acid and rutin—in apple tree bark, leaves, flower buds and twigs. The variety in the phenolic profiles of four apple tree cultivars was monitored during the vegetation period from March to September using chromatography analysis. Phloridzin, the major glycoside of interest, reached the highest values in the bark of all the tested cultivars in May (up to 91.7 ± 4.4 mg g⁻¹ of the dried weight (DW), cv. ‘Opal’). In the leaves, the highest levels of phloridzin were found in cv. ‘Opal’ in May (82.5 ± 22.0 mg g⁻¹ of DW); in twigs, the highest levels were found in cv. ‘Rozela’ in September (52.4 ± 12.1 mg g⁻¹ of DW). In the flower buds, the content of phloridzin was similar to that in the twigs. Aglycone phloretin was found only in the leaves in relatively low concentrations (max. value 2.8 ± 1.4 mg g⁻¹ of DW). The highest values of rutin were found in the leaves of all the tested cultivars (10.5 ± 2.9 mg g⁻¹ of DW, cv. ‘Opal’ in September); the concentrations in the bark and twigs were much lower. The highest content of chlorogenic acid was found in flower buds (3.3 ± 1.0 mg g⁻¹ of DW, cv. ‘Rozela’). Whole apple fruits harvested in September were rich in chlorogenic acid and phloridzin. The statistical evaluation by Scheffe’s test confirmed the significant difference of cv. ‘Rozela’ from the other tested cultivars. In conclusion, apple tree bark, twigs, and leaves were found to be important renewable resources of bioactive phenolics, especially phloridzin and rutin. The simple availability of waste plant material can therefore be used as a rich source of phenolic compounds for cosmetics, nutraceuticals, and food supplement preparation.     

固相萃取/毛细管气相色谱法测定肉桂皮中六六六、滴滴涕农药残留量

研究了肉桂皮中六六六、滴滴涕农药残留量的测定方法。以丙酮-石油醚混合溶剂为提取剂,旋涡振荡提取,采用固相萃取技术对提取液净化,优化洗脱溶剂的比例和用量,用气相色谱/微电子捕获检测器（μECD）测定。在优化条件下,BHC及DDT农药在10~1 000 μg/L质量浓度范围内线性关系良好,相关系数为0.995 8~0.998 1。2种农药在肉桂皮中的加标回收率为 92.1%~112%,相对标准偏差（RSD）为2.8%~8.1%,方法的检出限（LODs）为5.0×10-3~2.4×10-2 mg?kg-1,定量下限（LOQs）为1.3×10-2~6.0×10-2 mg?kg-1。方法具有简单、灵敏、选择性高、重现性好等优点。