EDTA滴定法直接测定镍铁中镍量

测定常量镍常采用丁二酮肟重量法或氨性分离-EDTA滴定法.但两者分析流程均较长而不适于快速分析.EDTA滴定法测定镍的应用已较为广泛[1-3].本工作采用氟化钠掩蔽铁、铝,六偏磷酸钠掩蔽锰,在过量的EDTA存在下,于pH约4.6的乙酸-乙酸盐缓冲介质中,以PAN作指示剂,用硫酸铜标准溶液返滴定过量EDTA的方法直接测定镍铁中镍.方法简便,分析结果满意.     

装运铁矿石取样的最佳实践

商业交易的装运铁矿石取样应当按照ISO 3082进行。尽管近年来合规性已有所改善,但在一些方面仍存在明显问题,包括:1)大流量样品截取器的设计和操作;2)在二级取样阶段对一级增量样品的划分;3)缩分之前用于减小样品粒度的破碎机的破碎性能;4)在每个取样阶段保留的样品质量;5)样品缩分。取样是测量过程开始的地方,因此如果样品不具有代表性,整个过程在开始时就被破坏了。正确取样的“金规则”是“被取样物料的所有部分都必须有相等的概率被收集到并成为最终分析样品的一部分”。如果不遵守这一规则,那么就很容易引入偏差。例如,在实践中不可能从库存料堆或船舶现场采集到具有代表性的样品。必须在构建堆料或分解堆料时,或在船舶的装载或卸载时取样。在满足“正确取样的金规则”后,取样站设计还应符合以下要求:1)采集的样品质量必须足够大,以考虑粒度大小的影响,将基本误差、分组误差和离析误差降低到可接受的水平;2)需要采取足够数量的增量样品,以将长期质量波动误差降低到可接受的水平;3)应正确地选择取样位置,以避免由于诸如斗轮取料机和离心泵等设备存在的质量周期性变化所造成的影响;4)附加错误诸如样品污染、样品溢出、颗粒降解和操作员失误等,需要从一开始就加以消除。因此为了消除不良的取样做法,确保取样能够兑现应有的承诺,需要通过改进工作人员的培训和提高认识来确保所取样品没有重大偏差,确保样品的总体精度满足所需的任务要求。     

助熔剂NaF对YAG∶Ce荧光粉结构及发光性能影响

利用化学共沉淀法,研究氟化钠助熔剂对YAG:Ce荧光粉结构及发光性能影响.采用XRD分析不同含量氟化钠助熔剂的YAG晶相形成过程,通过SEM和荧光光谱研究氟化钠助熔剂对其发光和形貌影响规律.结果表明,含氟化钠助熔剂的YAG:Ce荧光粉,合成温度可降低300℃,且不影响YAG晶相形成;随氟化钠添加量增加,荧光粉结晶度增加,发光强度增强;NaF添加量6%为最佳,其颗粒表面呈规则类球状,粒径1μm左右,分布较均匀,氟化钠在荧光粉晶相形成过程中除具有助熔剂作用外,Na+还具有电荷补偿的作用;探讨氟化钠引起荧光粉光致发光峰蓝移的机理.     

痕量组份分析中一个误差控制问题

本文介绍了在测定矿石和矿物这种物料中的痕量组份时,由于痕量组份通常存在于离析的异质矿粒中,由取样量的不同所产生的误差,并提出了利用取样常数控制这种误差的方法。首先对被分析物料实验测定取样标准偏差,或进行一些有关的化学测试和物理测试,以确定取样常数。然后根据取样常数即可确定对于一预定标准偏差的最小取样量。     

纺丝浴成分在线自动分析装置及分析方法等

公布号：CN105334287A
　　公布日：2016.02.17
　　申请人：唐山三友集团兴达化纤有限公司
　　摘要：一种纺丝浴成分在线自动分析装置,包括人机操作单元、电气控制单元、取样单元、分析单元和自动清洗单元,取样单元包括取样杯、取样电磁阀和蠕动泵;所述分析单元包括搅拌器、pH计和两个标准液储罐;人机操作界面与电气控制单元连接,电气控制单元分别与电磁阀、搅拌器、蠕动泵和pH计连接。这种纺丝浴成分的自动分析装置和方法,不仅能够对纺丝浴成分实现在线自动分析,还能对其设备进行在线自动冲洗,无需人工现场取样,降低工人劳动强度,提高工作效率和安全系数,计算比对测量,免去人工测量误差,提高测量精准度,适合各规模的纺丝企业使用。     

薄层色谱与红外光谱联用中新型固定相氟化钡的制备及应用

采用氟化钠与氯化钡反应制备了满足薄层色谱-红外光谱联用要求的氟化钡颗粒. 该方法虽然可以避免产生干扰红外光谱分析的碳酸钡杂质, 但氟化钡的产率偏低. 通过电感耦合等离子体(ICP)和X射线粉末衍射(XRD)分析证实, 氟化钠与氯化钡反应同时会生成氟氯化钡, 在沉淀洗涤过程中, 氟氯化钡的溶解会造成钡离子的流失和氟化钡产率的下降. 本文采用氟化钠溶液洗涤沉淀制备氟化钡, 可使氟氯化钡转化为氟化钡, 使氟化钡产率得到明显提高. 扫描电子显微镜和纳米粒度仪分析结果表明, 制备的氟化钡颗粒的粒径约为100 nm. 利用沉降挥发法制备了以氟化钡颗粒为固定相的薄层色谱板, 实验结果表明用该薄层色谱板可成功分离罗丹明B和孔雀石绿, 分离所得样品可被红外光谱检测且不受固定相的干扰.     

铝合金锭光电光谱分析的误差

在用光电直读光谱仪分析铝合金时,在不同激发点所取得的合金元素的测定结果,特别是硅的测定值,之间存在明显偏差,并证实系由合金的偏析所引起。通过改进取样方法,即将原来从铝合金锭的中间及两端截取块样,改为在铝锭的任意位置纵断面切块取样,有效地克服了不同激发点所得结果存在明显偏差的问题,使所得分析结果相互之间的偏差值很小而合理。     

饮水中痕量邻苯二甲酸酯类化合物的色谱测定

本文提出了包括疏水吸附剂富集及气相色谱或液相色谱分析方法。报道了邻苯二甲酸酯在Amberlite XAD-2和SS401上的富集容量,研究了水样pH和流速对回收率的影响,GC采用填充柱或毛细柱,HPLC采用细径反相柱,适用于分析大分子量邻苯二甲酸酯。当取样量为10升时,本法的检测极限为ppb水平。     

磷钼蓝光度法测定锰铁中磷

氟化钠-氯化亚锡磷钼蓝光度法测定磷的应用较广泛,但显色稳定性差.利用此法测定锰铁中磷的研究很少见报道.本文在前人经验的基础上,采用磷钼蓝直接光度法,试样以硝酸溶解,高氯酸发烟,亚硫酸钠还原高价锰,酒石酸钾钠掩蔽硅,试验了在硫酸介质中,用氟化钠-氯化亚锡还原磷钼黄为磷钼蓝,实现了锰铁中磷的测定.显色稳定性较好,已适用于锰铁脱磷工艺中批量分析,结果满意.     

基于光度法的高精度海水pH值测量系统

基于光度法的海水pH值自动测量系统测定速度快,精密度高,是海洋酸化和碳循环研究急需的测量装置.本研究以光度法和流动注射分析技术为基础,通过整合泵阀流路体系、LED光源、流通池和光谱仪,研发了海水pH值自动测量系统.本系统在分析过程中不易产生气泡,利用指示剂在样品中的浓度变化校正指示剂的加入带来的测量偏差,操作简单方便,测量一个样品用时约为1.5 min,精密度为0.0013,准确度为0.0059,可在实验室或调查船中对所采集的海水快速地进行高精度pH值测量.     

Kinetic determination of organosulphur ligands by inhibition: Trace determination of cysteine and maleonitriledithiolate (MNDT)

Some organosulphur ligands have been found to inhibit the mercury(II) catalyzed substitution of cyanide in hexacyanoferrate(II) by N-methylpyrazinium ion (Mpz⁺). The inhibitory effect is due to the binding tendency of catalyst Hg²⁺ with these inhibitors. This effect has been used as a basis to develop a kinetic method for the determination of trace amounts of two organosulphur ligands viz. cysteine and MNDT. The reaction was followed spectrophotometrically at 655 nm by measuring the decrease in absorbance of the product [Fe(CN)₅Mpz]²⁻. The influence of the reaction variables has also been studied. A general mechanistic scheme of the indicator reaction system including the role of inhibitor has been proposed and applied to determine the organosulphur ligands. Under the selected experimental conditions cysteine and MNDT have been determined in the range of 2–20 × 10^− 7 M and 5 × 10^− 8 M to 12 × 10^− 7 M respectively in various aqueous samples. The analytical concentration range depends upon the amount of Hg²⁺ present in the indicator reaction and also on the stability of the Hg²⁺-inhibitor complex in question. Under specified conditions, the detection limit for cysteine and MNDT are 2 × 10^− 7 M and 5 × 10^− 8 M respectively. The influences of possible interference by major amino acids, on the determination of cysteine and their limits have been investigated.     

极弱酸碱的pH滴定法研究

ｐＨ滴定法是指酸碱滴定至某一指定ｐＨ值时，即可根据滴定剂浓度，用量及有关公式，计算被测物浓度或含量的方法。本文深入讨论了测定原理，方法和应用，对１０种不同极弱酸碱进行了大量测定，测定结果相对误差一般在０．２％左右，相对标准偏差在０．３％左右，达到化不。ｐＨ滴定法具有简便，价廉，快速和通用的优点，为直接滴定极弱酸碱和化学分析仪化开辟了新的途径。     

Selective Enzymatic Determination of L-Phenylalanine and Phenyl-Pyruvate

Abstract

A simple enzymatic end point method for the determination of L-phenylalanine and 3-phenylpyruvate has been developed. The assay is based on the spectrophotometry determination of NADH formed or degraded in the reaction catalyzed with Thermoactinomyces intermedins phenylalanine dehydrogenase. This method enables the simple and selective determination of L-phenylalanine and 3-phenylpyruvate based on the high substrate specificity of the enzyme. The assay is sensitive in the range of 0.015?0.15 umol of L-phenylalanine and 3-phenylpyruvate.     

NMR Methods for Optical Purity Determination of Pharmaceuticals

Abstract

Although enantiomers normally have identical spectra, several methods for measurement of optical purity using NMR are possible: forming diastereomeric derivatives using chiral solvents and complexation with chiral reagents especially lanthanide shift reagents. The major limitation of these techniques as quantitative methods is the small chemical shift differences observed. However, with the availability of a wide range of lanthanide shift reagents, this problem is overcome. Several examples are cited for optical purity determinations of several pharmaceuticals using lanthanide shift reagents.     

Spectrophotometric analysis, thermal analysis and gravimetric determination of some metal ions with oxime and Schiff's base derivatives of N-furoylphenylhydroxylamine

The oxime and Schiff's base of N-furoylphenylhydroxylamine form complexes with Co²⁺, Cu²⁺, Zn²⁺ and Fe³⁺. These complexes were studied by means of the UV — Vis. spectra of nujol mulls, electron spin resonance (ESR) spectra and magnetic susceptibility to determine their stereochemistry. The complexes were characterized via elemental analyses, molar conductivities and thermogravimetric analyses. Organic reagents were used for the gravimetric determination of Co²⁺, Cu²⁺ and Fe³⁺ through the precipitation of their complexes. The compounds were also used for separation of a binary mixture of Cu²⁺ and Cu²⁺. Interferences were studied.     

Kinetic method for determination of nanogram amounts of copper(II) by its catalytic effect on hexacynoferrate(III)-citric acid indicator reaction

This paper describes a highly sensitive, selective catalytic-kinetic-spectrophotometric method for the determination of copper(II) concentration as low as 6 ng ml⁻¹. The method is based on the catalytic effect of copper(II) on the oxidation of citric acid by alkaline hexacyanoferrate(III). The reaction was followed by measuring the decrease in absorbance of hexacyanoferrate(III) at 420 nm (λ_max of [Fe(CN)₆]³⁻, ∈ = 1020 dm³ mol⁻¹ cm⁻¹). The dependence of rate of the indicator reaction on the reaction variables has been studied and discussed to propose a suitable mechanism to get a relation between the reaction rate and [Cu²⁺]. A fixed time procedure has been used to obtain a linear calibration curve between the initial rate and lower [Cu²⁺] or log[Cu²⁺] in the range 1 × 10⁻⁷ to 4 × 10⁻⁴ mol l⁻¹ (6.35-25,400 ng ml⁻¹). The detection limit has been calculated to be 4 ng ml⁻¹. The maximum average error is 3.5%. The effect of the presence of various cations, commonly associated with copper(II) and some anions has also been investigated and discussed. The proposed method is sensitive, accurate, rapid and inexpensive compared to other techniques available for determination of copper(II) in such a large range of concentration. The new method has been successfully applied for the determination of copper(II) in various samples.     

快速测定COD最佳催化消解体系研究

通过正交试验 ,确定了测定环境水样中COD的最佳回流消解条件。以CuSO4作催化剂 ,KAl(SO4) 2 Na2 MoO4作助催化剂 ( 0 1 8gCuSO4·5H2 O 0 1 0gKAl(SO4) 2 ·1 2H2 O 0 1 0gNa2 MoO4·2H2 O) ,在H2 SO4 H3PO4体系中可很好地实现对样品的消解。该体系将回流时间由国标法的 2h缩短至 2 0min ,实现了快速测定的目的且大幅度降低测定成本。样品 1 0次平行测定的相对标准偏差为 1 1 % ;加标回收率为 97 7%～ 1 0 3 3% ,均与国标法无显著性差异     

Application of ruthenium catalyzed oxidation of [tris(2-aminoethyl)amine] in trace determination of ruthenium in environmental water samples

The ruthenium catalyzed oxidation of tris(2-aminoethyl)amine (TREN) by hexacyanoferrate(III) has been utilized for the development of a new and sensitive catalytic kinetic method (CKM) for the determination of ruthenium(III). The reaction was followed spectrophotometrically by the decrease in absorbance at 420nm (lambda(max) of [Fe(CN)(6)](3-)). The CKM developed utilizes fixed time procedure under optimum reaction conditions where the change in absorbance (DeltaA(t)) versus ruthenium(III) concentrations is plotted. The calibration curve recommended for the method is linear in the concentration range 10.11-252.67ngml(-1) with very good accuracy and reproducibility and a maximum error 2.20%. The detection limits of the method for ruthenium(III) corresponding to 10, 15 and 20min are 8.02, 5.03 and 3.15ngml(-1), respectively. The ruthenium(III) has also been determined in the presence of several other interfering and non-interfering cations and anions and no foreign ions interfered in the determination of ruthenium(III) up to five-fold higher concentration of the foreign ions tested. The method is highly sensitive, selective and stable. It has successfully been applied for the determination of trace ruthenium(III) in some synthetic and environmental water samples. A review of most of the published catalytic kinetic and some other important methods for the determination of ruthenium has also been presented.     

钐钆富集物中钐、钆的同时测定

本文初步探讨了稀土的DBC偶氮刖络合物与CyDTA取代反应机理。对于不同显色剂和取代剂进行了选择，建立了测量钐、钆的最佳反应体系，用速差动力分析法进行了钐钆富集物中钐、钆的同时测定。速差动力分析结果与ICP发射光谱法结果相符。本法测定钐、钆相对含量在1：2－4：1范围，误差约为10％。     

雪松烯的光氧化反应研究

以次甲基兰为光敏剂, 甲醇为溶剂, 用通氧光照产生的单重态氧与雪松烯反应,产物只有一种。用元素分析、红外光谱。核磁共振谱、质谱以及高压液相色谱等方法测定了产物的分子结构。并讨论了光氧化反应的动力学控制和立体效应。