Determination of pah in soil samples by high-performance thin-layer chromatography (HPTLC)

A thin-layer Chromatographic screening-method is presented for the determination of polycyclic aromatic hydrocarbons (PAH) in soil samples. This screening method is intended for a quick overview of the composition of a contaminant. The developed method of separation is well suited for the semi-quantitative determination of PAH in soil samples, and can be used to identify samples that require further analysis by means of GC or HPLC. The separation of 8 PAH groups with a maximum of 2 PAH (discernible by selective excitation of fluorescence) each is possible. The results of the analysis based on PAH group separation can be regarded as semi-quantitative. The extraction of PAH is effected by means of a solvent mixture consisting of n-hexane-acetone (1:1, v/v). The extraction is aided by ultrasonic treatment. The extract is purified by application to an activated silica gel column (solid-phase extraction). The qualitative analysis can be carried out either by visual observation or by fluorimetric scanning (TLC-Scanner). The characteristic fluorescent colours facilitate a reliable visual identification of PAH. The applicability of the method is shown and a comparison to other analytical methods is carried out. Some of the remarkable features of this method are its user-friendly handling, the low consumption of solvents and the applicability without the necessity for extra equipment.     

不同样本序列下侵蚀性雨量标准的研究

侵蚀性降雨标准可以将发生侵蚀和不发生侵蚀的降雨区分开来 ,但它的拟定需要基于一定的降雨样本。利用黄河流域子洲径流实验站 196 2— 196 9年降雨径流观测资料 ,分析了不同样本年数与拟定的侵蚀性雨量标准的关系 ,结果表明 ,足够多的样本数才能保证雨量标准的稳定性 ,但考虑到资料的易获得性和计算的工作量 ,5a序列的观测资料 ,已经满足拟定侵蚀性雨量标准的要求。     

A new sediment contact assay to assess particle-bound pollutants using zebrafish (<Emphasis Type="Italic">danio rerio</Emphasis>) embryos

Goal, Scope and Background. Based on a bioassay battery covering only primary producers and consumers as well as degraders, the potential ecological hazard of sediments to vertebrates cannot be estimated comprehensively. Therefore, there is an urgent need to develop and standardize integrated vertebrate-based test systems for sediment investigation strategies. Whereas vertebratebased in vitro systems have frequently been used for the investigation of aqueous samples, there is a significant lack of whole sediment assays. Thus, the purpose of the present study was: (1) to develop a rapid and reliable, but comprehensive method to investigate native sediments and particulate matters without preceding extraction procedures; (2) to compare the hazard potential of solid phase sediments to the effects of corresponding pore waters and organic extracts in order to characterize the bioavailability of the particle-bound pollutants; and (3) to relatively evaluate the embryotoxic effects of sediments from the catchment areas of the rivers Rhine, Neckar and Danube. Methods (or Main Features).  To investigate the toxicity of sediment samples on vertebrates, the standard embryo toxicity test with the zebrafish (Danio rerio; Hamilton-Buchanan 1922) according to DIN 38415-6 was modified with respect to exposure scheme and toxicological endpoints. Sediments from the catchment area of the Neckar River were assessed using pore waters, acetonic extracts and native sediments in order to get inside into the potential bioavailability of particle-bound pollutants. A comprehensive test protocol for the investigation of native sediments in the embryo toxicity test with the zebrafish is presented. Results and Discussion.  The fish embryo assay with Danio rerio can be carried out with both aqueous and organic sediment extracts as well as native (whole, solid phase) sediment samples. Elongation of exposure time from 48 to up to 196 h significantly increased the mortality. Using the fish egg assay with native sediments, a broad range of embryotoxic effects could be elucidated, including clear-cut dose-response curves for the embryotoxic effects of contaminated sediments; in contrast, absence of embryotoxic effects could be demonstrated even for the highest test concentrations of unpolluted sediments. With native sediments, embryotoxicity was clearly higher than with corresponding pore waters, thus corroborating the view that — at least for fish eggs — the bioavailability of particle-bound lipophilic substances in native sediments is higher than generally assumed. The relative ranking of sediment toxicity was identical using both native sediments and sediment extracts, EC₂₀ values of the latter, however, being eight time lower higher than with the native sediments. A comparison of the embryo toxic effects of samples from the Neckar area with locations along the Rhine and Danube rivers elucidated a broad range of results, thus indicating different levels of contamination. Conclusions.  A modified protocol of the zebrafish embryo test allows the assessment of sediment toxicity in both aqueous extracts and native sediments. The isolated investigation of pore waters may result in a clear-cut underestimation of the bioavailability of lipophilic particle-bound substances (as determined by native sediments). Recommendations and Perspectives.  The zebrafish embryo test with native (whole, solid phase) sediments appears very promising for the evaluation of the bioavailable fraction of lipophilic particle-bound substances and can therefore be recommended for the evaluation of vertebrate toxicity in tiered sediment test strategies and dredging directives such as the HABAB-WSV. Whereas acetone extracts may be tested as a rough estimation of embryotoxicity, native sediment samples will provide a more comprehensive and realistic insight into the bioavailable hazard potential     

扫描电镜不同制样方法对果梅花粉形态的影响

本试验任意选取３个果梅品种作为试材,利用Ｏｌｙｍｐｕｓ光学显微镜观察了新鲜花粉、风干花粉和不同浓度藏二醛固定处理花粉的极轴长（Ｐ）、赤道轴长（Ｅ）、Ｐ／Ｅ;结果表明,２．５％－３．５％戊二醛固定液处理对梅花粉形态影响甚小。在扫描电镜下,观察了这３个品种的新鲜花粉,风干花粉和２．５％戊二醛固定处理花粉的形态特征,对光镜的实验结果进行了验证。     

奶牛瘤胃胃液微生物总DNA的提取和纯化

本研究建立了从奶牛瘤胃液中提取混合微生物总DNA的方法，对现有的方法进行改进使其适合于瘤胃混合微生物总DNA的提取。粗提后的瘤胃DNA可以直接扩增出16SrDNA。提取效率为每毫升瘤胃液的DNA提取量为0.1～0.3μg。通过SiO2回收进行纯化，纯化回收率达到34%～50％；用clean-up试剂盒纯化，纯化率可达到85％以上。经过纯化后的DNA可进行其它的分子生物学操作。     

土壤质量评价中少量样本最小数据集的构建——以内蒙古杭锦旗黄河南岸灌区典型地块为例

为研究土壤质量评价过程中样本容量较少情况下最小数据集的构建方法。采集并测定内蒙古杭锦旗黄河南岸灌区典型地块的12个土壤理化指标,利用聚类分析、相关分析和主成分分析等探讨了少量样本最小数据集的构建方法。结果表明:1)通过聚类分析、相关分析和主成分分析所构建的最小数据集中的指标包括土壤容重、饱和含水量、土壤电导率、阳离子交换量、硝态氮、速效钾、速效磷;2)全体数据集与最小数据集的土壤质量指数呈显著正相关,R2达到了0.735,Nash有效系数为0.917,偏差系数为0.057;3)基于全体数据集和最小数据集计算得出的土壤质量指数变化范围分别是0.47~0.73和0.37~0.75,平均值为0.56和0.53,表明研究地块土壤呈现中等质量水平。研究发现,在黄河南岸灌区典型地块基于少量样本进行土壤质量评价的过程中,使用聚类分析、相关分析、主成分分析3种分析方法可以构建最小数据集,且检验精度较高。     

Analytical challenges: determination of tetrodotoxin in human urine and plasma by LC-MS/MS

Tetrodotoxin (TTX) is a powerful sodium channel blocker found in puffer fish and some marine animals. Cases of TTX poisoning most often result from puffer fish ingestion. Diagnosis is mainly from patient's signs and symptoms or the detection of TTX in the leftover food. If leftover food is unavailable, the determination of TTX in the patient's urine and/or plasma is essential to confirm the diagnosis. Although various methods for the determination of TTX have been published, most of them are for food tissue samples. Dealing with human urine and blood samples is much more challenging. Unlike in food, the amount of toxin in the urine and blood of a patient is generally extremely low; therefore a very sensitive method is required to detect it. In this regard, mass spectrometry (MS) methods are the best choice. Since TTX is a very polar compound, there will be lack of retention on conventional reverse-phase columns; use of ion pair reagent or hydrophilic interaction liquid chromatography (HILIC) can help solve this problem. The problem of ion suppression is another challenge in analyzing polar compound in biological samples. This review will discuss different MS methods and their pros and cons.     

杨树根材纤维形态及化学成分分析

【目的】对杨树根材的纤维形态和化学成分进行研究,为杨树根材的开发利用提供理论依据。【方法】以2012年采自合肥大圩的12年生意杨无性系I-69杨(Populus deltoids Bartr cv."Lux")的根材为研究对象,采用常规方法制作根材切片,观测其纤维宽度、纤维壁厚及细胞腔径,采用冰醋酸与双氧水混合溶液离析法测定根材纤维长度,参照GB/T 2677.(2-10)-1993规定的造纸原料成分测定系列方法分析根材的化学成分。【结果】I-69杨根材纤维平均长度为1 068.37μm,平均长宽比为37.56,平均壁腔比为0.73;I-69杨根材综纤维素平均含量为83.96%,酸不溶木质素平均含量为22.34%,戊聚糖平均含量为20.43%,苯醇抽提物平均含量为3.84%。【结论】与相关文献资料提供的杨树同一品系干材相比,根材纤维长度较短,长宽比较小,壁腔比较大,综纤维素含量较高,酸不溶木质素含量相近,戊聚糖含量偏低,苯醇抽提物含量高出近1倍。     

Boron analysis in soil extracts and plant tissue by plasma emission spectroscopy

Abstract

Nine Colorado soils were treated with sodium borate and were subjected to 3 wetting and drying cycles. These soils were extracted with hot water for boron analysis. Plant samples, including NBS standard reference materials (SRM) 1571, 1570, 1573, were dry ashed and wet digested using nitric acid. All soil extracts and plant digests were analyzed for boron using ICP‐AES and colorimetrically using the Azomethine‐H method.

A high degree of correlation (r² = .99) was found between boron determination by ICP and the Azomethine‐H method for soil extracts and plant digests. The Azomethine‐H method gave B values 9% higher than ICP‐AES on the average.

Boron levels determined by ICP were similar to NBS boron values for both the dry ashed and wet digested SRM plant samples. Boron levels determined colorimetrically were comparable to the NBS values for dry ashed SRM plant samples. Plant samples digested in nitric acid could not be analyzed for boron by the Azomethine‐H colorimetric method due to interferences resulting from nitrate complexes in the wet digest.