Gold Characterization by MLA and Technological Tests-Discussion of Sample Preparation and Results

Gold has been present throughout the history of mankind and used to make jewelry and coins, and recently, acquired several industrial uses. The price of gold in international market had a significant increasing, surpassing 100% in the last five years. Thereby, deposits with low levels of gold content, gold with complex associations or in a very fine particle size became exploitable again, allowing new projects and expansion of existing ones. However, for maximum process efficiency is indispensable a deep knowledge of the characteristics of these minerals and their behavior in face of beneficiation processes. Consequently, an accurate routine for mineralogical and technological characterization is essential.

Quantitative Analysis of Heavy Metals in Water Based on LIBS with an Automatic Device for Sample Preparation

Abstract Heavy metals in water can be deposited on graphite flakes, which can be used as an enrichment method for laser-induced breakdown spectroscopy （LIBS） and is studied in this paper. The graphite samples were prepared with an automatic device, which was composed of a loading and unloading module, a quantitatively adding solution module, a rapid heating and drying module and a precise rotating module. The experimental results showed that the sample preparation methods had no significant effect on sample distribution and the LIBS signal accumulated in 20 pulses was stable and repeatable. With an increasing amount of the sample solution on the graphite flake, the peak intensity at Cu I 324.75 nm accorded with the exponential function with a correlation coefficient of 0.9963 and the background intensity remained unchanged. The limit of detection （LOD） was calculated through linear fitting of the peak intensity versus the concentration. The LOD decreased rapidly with an increasing amount of sample solution until the amount exceeded 20 mL and the correlation coefficient of exponential function fitting was 0.991. The LOD of Pb, Ni, Cd, Cr and Zn after evaporating different amounts of sample solution on the graphite flakes was measured and the variation tendency of their LOD with sample solution amounts was similar to the tendency for Cu. The experimental data and conclusions could provide a reference for automatic sample preparation and heavy metal in situ detection.

Applied Study on Magnetic Nanometer Beads in Preparation of Genechip Samples

A protocol for enrichment and adsorption of karyocyte from whole blood by using magnetic nanometer beads as solid phase absorbents was presented. The PCR amplification could be accomplished by using the nanobeads with karyocyte as template directly and the PCR products were applied on an oligonucleotide array to do gene typing. The HLA A PCR amplification system and a small HLA A oligonucleotide microarray were applied as the platform and an experiment protocol of separating karyocyte from whole blood using the magnetic nanometer beads (Fe 2O 3) were set up. The experimental conditions were also discussed. It showed that pH level of PBS eluent, Taq enzyme quantity and fragment length of products could influent the amplification results, and the magnetic nano beads could succeed in sample preparation in microarray to provide a promising way in automatic detection and lab on a chip.

Sample preparation for isotopic determination of boron in clay sediments

The procedures of sample preparation for isotopic determination of boron in clay sediments is very cumbersome, by far, there haven't been relevant reports on that. In order to establish an effective method for sample preparation, a series of experiments were carried out. In this paper, boron in clay sediments was extracted with HCl solution and purified by two-step ion exchange method. Extracted HCl solution should be adjusted to alkalescency before passing through the Amberlite IRA 743 resin column due to the fact that Amberlite IRA 743 resin absorbs boron only from alkalescent solution. However, a mass of hydroxides of Al and Fe will be precipitated when the extracted HCl solution becomes alkalescent. Hydroxides of Al and Fe have a strong adsorption capacity for boron, which can cause boron isotope fractionation. To treat precipitated hydroxides of Al and Fe, four procedures, namely direct ion exchange (DRIE), decationizing ion exchange (DCIE), once sedimentation ion exchange (OSIE) and repeated sedimentation ion exchange (RSIE) were used and assessed. The influences of the four procedures on separation and extraction and isotopic composition of boron in experimental solutions and clay sediments were also discussed. According to the results, the DRIE, DCIE and OSIE are improper. The result of sample determination indicates that when extracting boron via RSIE, with the increase of precipitation times, there's an obvious decrease in boron content in the precipitated hydroxides while a sharp increase in recovery of boron and it is favorable for weakening the influence of boron isotope fractionation. But the process of RSIE is time consuming and it may introduce boron. It needs further research to establish a more effective sample preparation method for isotopic deter- mination of boron in clay sediments.

Sample Preparation for Monolithic Refractories Part 1:Refractory Castables

1 Scope This standard specifies the definition and test methods of flowability of dense and insulating refractory castables, and moulding equipment, moulding methods, curing and drying conditions of castables samples.

Prediction to the Efficiency of Soft Clay Sample Preparation with Vacuum Loading

Vacuum loading has been examined as a way of preparing uniformly consolidated soft clay samples. The facility and loading procedure are described in this paper. An analytical solution to the three dimensional consolidation equation is derived for estimating the degree of consolidation of the soil sample with vacuum loading. The given example shows that the predicted degree of consolidation of a soft clay bulk with vacuum loading is close to that measured in the consolidation process.

Evaluation of HemogloBind^TMtreatment for preparation of samples for cholinesterase analysis

Acetylcholine is an essential neurotransmitter found throughout the nervous system. Its action on postsynaptic receptors is regulated through hydrolysis by various carboxylesterases, especially cholinesterases (ChEs). The acute toxicity of organophosphate (OP) compounds is directly linked to their action as inhibitors of ChE. One widely used assay for evaluating ChE activity is a spectrophotometric method developed by Ellman et al. When the enzyme source is from tissues or, in particular, blood, hemoglobin displays a spectrophotometric peak at the same wave-length used to analyze cholinergic activity. This creates a substantial background that interferes with the Ellman’s assay and must be overcome in order to accurately monitor cholinesterase activity. Herein, we directly compare blood processing methods: classical method (1.67 ± 0.30 U/mL) and HemogloBindTM treatment (1.51 ± 0.17 U/mL), and clearly demonstrate that pretreatment of blood samples with HemoglobindTM is both a sufficient and rapid sample preparation method for the assessment of ChE activity using the Ellman’s method.

A Comparison of Weighing Methods Prior to Fusion Preparing Iron Samples for XRF Analysis

Sample preparation by fusion for XRF analysis is all about knowing the exact weights of the sample and the flux (sample-to-flux ratio). The whole analytical chain, including the weighing step in sample preparation prior to fusion, is of crucial importance to get precise and accurate x-ray fluorescence (XRF) results. Consequently, the weighing method will affect the quality of the analytical results given by the spectrometer. In this study, the effects of different weighing methods on the precision (RSD) of the obtained XRF results are compared to determine the best weighing method for sample preparation by fusion in terms of comparable precisions in the XRF results.

Analytical quality-by-design approach for sample treatment of BSA-containing solutions

The sample preparation of samples conlaining bovine serum albumin（BSA）,e.g..as used in transdermal Franz diffusion cell（FDC） solutions,was evaluated using an analytical qualily-by-design（QbD）approach.Traditional precipitation of BSA by adding an equal volume of organic solvent,often successfully used with conventional HPLC-PDA,was found insufficiently robust when novel fused-core HPLC and/or UPLC-MS methods were used.In this study,three factors（acetonitrile（%）.formic acid（%） and boiling time（min）） were included in the experimental design to determine an optimal and more suitable sample treatment of BSAcontaining FDC solutions.Using a QbD and Derringer desirability（D） approach,combining BSA loss,dilution factor and variability,we constructed an optimal working space with the edge of failure defined as D〈0.9.The design space is modelled and is confirmed to have an ACN range of 83 ± 3% and FA content of 1 ±0.25%.

High Density Solvent Based Dispersive Liquid-Liquid Microextraction Technique for Simultaneous and Selective Extraction of Multiclass Pesticide Residues in Water and Sugarcane Juice Samples

In this study, a miniaturized analytical technique based on high density solvent based dispersive liquid-liquid microextraction (HD-DLLME) was developed for extraction of trace residues of multiclass pesticides including three striazine herbicides, two organophosphate insecticides and two organochlorine fungicides from environmental water and sugarcane juice samples. The analytical method was validated and found to offer good linearity: R2 ≥ 0.991;repeatability varied from 0.73% - 5.28%;reproducibility varied from 1.14% - 8.74% and limit of detection ranged from 0.005 to 0.02 μg/L. Moreover, accuracy of the optimized method was evaluated and the recovery was varied from 80.39% - 114.05%. Analytical applications of this method to environmental waters and sugarcane juice samples indicate the presence of trace residues of ametryn in the lake water and sugarcane juice samples. Atrazine and ametryn were also detected in irrigation water.

Variations of trace elements and rare earth elements(REEs)treated by two different methods for snow-pit samples on the Qinghai-Tibetan Plateau and their implications

Although previous investigations of the trace elements in snow and ice from the Qinghai-Tibetan Plateau obtained interesting information about pollution from human activities on the plateau, most were based on traditional acidification methods.To emphasize the influence of the different sample-preparation methods on the records of trace elements and rare earth elements, snow samples were collected from glaciers on the Qinghai-Tibetan Plateau in China and prepared using two methods: traditional acidification and total digestion. Concentrations of 18 trace elements(Al, Ti, Fe, Rb, Sr, Ba, V, Cr, Mn, Li,Cu, Co, Mo, Cs, Sb, Pb, Tl, and U), along with 14 rare earth elements(REEs: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er,Tm, Yb, and Lu), Y, and Th in the snow samples, were measured using inductively coupled plasma-sector field mass spectrometry(ICP-SFMS). The results showed that the mass fraction of the trace elements(defined as ratio of concentration in the acid-leachable fraction to that in the digested sample) such as Mo, Ti, Al, Rb, and V, varied from 0.06 to 0.5. The mass fraction of other trace elements varied from about 0.6 to more than 0.9; those of the REEs, Y, and Th varied from 0.34 to0.75. Lower mass fractions will lead to an overestimated contribution of other sources, especially human activities, and the underestimated fluxes of these trace elements(especially REEs, Y, and Th, as well as dust) if the REEs are used as the proxy for the crust dust. The two sample-preparation methods exhibited different REE normalized distribution patterns,REE ratios, and provenance-tracing results. The REE normalized distribution patterns and proxies in the digested samples are more reliable and integrated than those found in traditional acidification method for dust-provenance tracing.

Distribution and Accumulation of Major and Trace Elements in Gypsum Samples from Lignite Combustion Power Plant

Flue gas containing volatile elements, fine fly ash particulates not retained by particle control devices, and limestone are the most important sources of trace and major elements (TMEs) in wet flue gas desulphurization (WFGD) gypsum. In this study, samples of gypsum slurry were separated into fine and coarse fractions. Multi-elemental analysis of 45 elements in the different size fractions of gypsum, slurry waters and lignite were performed by k0-INAA (k0-instrumental neutron activation analyses). The study found that the volatile elements (Hg, Se and halogens) in the flue gas accumulate in the fine fractions of gypsum. Moreover, the concentrations of most TMEs are considerably higher in the fine fractions compared to the coarse fractions. The exceptions are Ca and Sr that primarily originate from the limestone. Variations of TMEs in the finer fractions are dependent on the presence of CaSO4·2H2O that is the main constituent of the coarse fraction. Consequently, the content of TMEs in the fine fraction is highly dependent on the efficiency of separating the fine fraction from the coarse fraction. Separation of the finer fraction, representing about 10% of the total gypsum, offers the possibility to remove effectively TMEs from WFGD slurry.

A Graphene-Based Aerogel Was Prepared as Solid Adsorbent for the Enrichment of Platinum (IV) at Trace Concentration

A three-dimensional graphene-based composite was prepared by a simple one-step in-site reduced-oxide method under atmospheric pressure. The obtained hydrogel was modified with 4-amino-benzenesulfonic acid and connected with ethylenediamine, and freeze-dried into an aerogel, which was characterized. Then the surface interaction with platinum (Pt, IV) was explored. The obtained aerogel showed good adsorption for Pt (IV) at acid conditions, giving a rising to the adsorption rate > 98% while pH ≥ 6. Using hexadecyl trimethyl ammonium bromide of 2% (m/V) as an eluent to desorb the Pt (IV) from the surface of the aerogel, a desorption rate of 81.1% was obtained in this process. Urea, buffer aquation and other surfactants were used in the desorption experiment to understand the adsorption mechanism between the aerogel and Pt (IV). In this work, hydrogen bond, van der Waals force and electronic interaction force mainly drove the adsorption process. For obtaining more purified Pt (IV), we used 0.5% CTAB to desorb Pd (II). A new three-dimensional graphene-based composite was prepared and the surface interaction between Pt (IV) and composite was experimented for understanding the adsorption mechanism and exploring its potential application in sample preparation in low concentration.

松软破碎煤体取制样与剪切试验系统研制及应用

研究松软破碎煤体力学性质对巷道支护和煤与瓦斯突出预测等工作具有重要意义,但当前缺乏有效的松软破碎煤体取样、制样及力学特性分析装置。为此,研发了一套松软破碎煤体取制样与剪切试验系统,主要由取样装置、制样装置和力学特性参数测试系统组成,各部分具有以下主要功能与特点:①取样装置中的单动三管取芯器包含脑袋总成、外管总成及内管总成3部分,内外管间设置稳定环,保证内外管同心,内管总成腔体内部设置衬管用于储存煤心,取芯钻进时内管不随外管旋转;当钻取的煤心充满衬管后,退出取芯器,拆卸取出衬管,将煤心连同衬管一并取出并进行封装。取样装置灵活、轻便、易拆装携带。②制样装置包含脱模仪、切割机、冰箱、热风枪4部分,脱膜仪用于脱去煤心外层衬管,切割机、冰箱和热风枪用于对煤心进行切割、冷冻和热缩;制作标准煤心试件分为打孔润湿、冷冻切割和热缩脱模3个步骤,采用端头局部冷冻切割、脱模与热缩均匀同步等技术,实现多种标准尺寸试件制备,制样方法完善、成功率高。③力学特性参数测试系统包含主体结构、伺服油源控制装置和软件系统3部分,能实现限制性及非限制性直剪试验功能,主要用于开展松软破碎煤体标准试件不同法向应力下直剪试验、不同围压下三轴压缩试验。整体设计结构简单、操作方便。研究利用单动三管取芯器获取松软破碎煤体,利用脱模仪等制样装置将其制备成标准试件,进而在力学特性参数测试系统上分别开展松软破碎煤体标准试件在0.04、0.05、0.06、0.07、0.08、0.09 MPa法向应力下的直剪试验和0.2、0.3、0.4 MPa围压下的三轴压缩试验,并求得两种试验条件下松软破碎煤体的黏聚力和内摩擦角等抗剪强度参数,其中直剪试验求得的黏聚力和内摩擦角为0.125 kPa和37.2°,三轴压缩试验求得的黏聚力和内摩擦角为0.121 kPa和36.4°。结果表明,该套系统具有较好的实用性和可靠性,为研究松软破碎煤体力学特性提供了较好的试验平台和方法。

冷冻扫描电镜制样方法及其在含水样品中的应用

常规扫描电镜要求所观察的样品必须干燥、无水,而一些含水样品在干燥过程中会发生结构变化,无法真实反映样品的结构信息。冷冻扫描电镜无需对样品进行干燥处理,可以直接分析含水样品表面、界面和内部结构,是研究高度含水样品的强有力工具。样品的制样方法在冷冻扫描电镜技术中占有重要地位,它直接关系到样品真实形貌特征的反映和对超微结构的正确解读。本文综述了冷冻扫描电镜的制样方法,并阐述冷冻扫描电镜技术在天然气水合物、微生物、乳液、水凝胶、动植物等含水样品中的应用。

扫描电镜精子样品快速制备方法

常规扫描电镜精子样品制备方法易出现精子团聚、形变等结构表征缺陷,而且大部分少精样品无法满足制样要求。为了改进技术,在精子样品制备过程中引入一种多元醇生物相容性聚合物,重悬固定后的精子样品均匀涂布于硅片上,经自然干燥后可直接用于扫描电镜观察。优化后的扫描电镜精子样品制备流程及方法可大幅改善扫描电镜精子样品成像效果。

柽柳属植物盐腺的扫描电镜制样方法比较及观察

为研究柽柳属(Tamarix)植物的盐腺特征,本研究首先采用CO_(2)临界点干燥法和冷冻扫描电镜(Cryo-SEM)制样法两种方法,分别对刚毛柽柳(T.hispida)组培苗和土培苗的叶片进行前处理,并在扫描电镜下观察比较盐腺的形态特征差异。结果发现,对于幼嫩的组培苗,Cryo-SEM制样镜检效果好于CO_(2)临界点干燥制样,盐腺更少变形;对于肉质化的土培苗,CO_(2)临界点干燥制样效果更好,分辨率和衬度较好。接着本研究对10种柽柳土培苗叶片进行了常规干燥制样和扫描电镜观察,并统计了盐腺数量和面积,结果可见长穗柽柳(T.elongata)的盐腺数量和面积均为最高。本研究比较了两种制样法对观察柽柳盐腺形态的优劣且进一步研究了10种柽柳叶片的盐腺,为柽柳抗盐相关基础和应用研究提供一定的参考。