Spectrophotometric determination of zinc in copper-base alloys with TAN

TAN reacts with zinc(II) forming a red complex with composition 1:2 Zn(II)-TAN and absorption maximum at 582 nm. Zinc can be determined with this reagent in the presence of Triton X-100, in the pH range 6.20-8.00 with a molar absorptivity of 4.5×10⁴ l/mol/cm Beer's Law was obeyed up to least 1.55 g/ml. Copper interference was eliminated with a mixture of thiosulfate and ascorbic acid and nickel separated by precipitation with dimethylglyoxime. The proposed method was used for zinc determination in several copper-base alloys and the results of analysis in comparison with certified values indicated that the procedure was accurate and precise. A derivative procedure is also proposed, allowing zinc determination with high sensitivity (5-400 ng/ml).     

Combination of three analytical techniques for speciation of Al in environmental samples

An analytical scheme is proposed which combines three speciation techniques for determination of particular Al species in soil extracts and percolating waters. A cation-exchange fast protein liquid chromatography — inductively coupled plasma atomic emission spectrometry (FPLC-ICP-AES) procedure, a microcolumn chelating ion-exchange chromatography- atomic absorption spectrometry (MCC-ETAAS) technique and the 8-hydroxyquinoline spectrophotometric method (8HQ-spectrophotometry) were employed. The FPLC-ICP-AES procedure offers determination of Al³⁺ (retention time 4.5 min) and Al(OH)²⁺ species (retention time 4.0 min) which are separated from Al(OH)⁺ ₂ (retention time 1.5min). AlF²⁺ coelutes with Al(OH)²⁺ species, while Al(SO₄)⁺, AlF⁺ ₂ and negatively charged Al organic complexes coelute with Al(OH)⁺ ₂ species. The MCC-ETAAS technique enables determination of the sum of positively charged monomeric aqua- and hydroxy-Al species plus sulphate- and fluoro-Al complexes. Employing the 8HQ-spectrophotometry the sum of positively charged monomeric aqua- and hydroxy-Al species plus sulphato- and most of the labile organic Al species are determined. The sensitivities of these selected techniques were adequate for speciation of Al in the samples analyzed. On the basis of the specific selectivity of a particular technique various groups of Al species may be determined. Thus, the comparison of analytical data from complementary procedures provides more comprehensive information on Al species present in soil extracts and percolating waters.     

Spectrophotometric methods for the determination of labetalol hydrochloride in pure and dosage forms

Simple and sensitive Spectrophotometric methods for the determination of labetalol hydrochloride are described. The first two are based on the oxidative coupling reaction of labetalol hydrochloride withp-N,N-dimethyl-phenylenediamine dihydrochloride (method A, _max 685 nm) and 3-methyl-2-benzothiazolinone hydrazone hydrochloride (method B, _max 545 nm) in the presence of sodium hypochlorite and eerie ammonium sulphate as oxidants, respectively. The third depends on the formation of an ion-association complex of labetalol hydrochloride with suprachen violet 3B at pH 1.3, which is extracted into chloroform (method C, _max 565 nm). The methods obey Beer's law and the precision and accuracy of the methods were checked against the B.P. reference method and the relative standard deviations were in the range 0.35–0.52%. These methods are applied to the determination of labetalol in dosage forms.     

双波长分光光度法同时测定浆料中的聚乙烯醇和淀粉

本文报道了用双波长分光光度法同时测定变性聚乙烯醇和淀粉醋酸酯的一种新方法。分别选择670.0～540.0nm以及590.0～730.0nm波长对测定变性聚乙烯醇和淀粉醋酸酯。变性聚乙烯醇)～32μg/ml,淀粉醋酸酯0～130μg/ml浓度范围内,吸光度差值△A遵循比耳定律。当淀粉醋酸酯与变性聚乙烯醇的浓度比在1.3～16范围内,变性聚乙烯醇和淀粉醋酸酯的样品回收率分别为99.5～105%和97～108%。所拟定的方法可测定浆料中变性聚乙烯醇和淀粉醋酸酯。本法与盐酸水解淀粉法测定的聚乙烯醇含量相吻合。本法简便快速。     

2－（5－Br－2－吡啶偶氮－5－二乙氨基）－酚与铑的显色反应的研究及应用

本文研究了２－（－５－Ｂｒ－２吡啶偶氮－５－二乙氨基）－酚与铑（Ⅲ）的显色反应。在ｐＨ为４．０的邻苯二甲酸氢钾缓冲液介质中，Ｒｈ（Ⅲ）与试剂形成稳定的橙红色络合物，其组成比为１：４，最大吸收波长为４９０ｎｍ，表现摩尔吸光系数为１．３×１０￣５Ｌ·ｍｏｌ￣（－１）·ｃｍ￣（－１）。铑含量在０～４μｇ／１０ｍＬ范围内服从比尔定律。     

偏最小二乘-速差动力学分光光度法同时测定杀虫剂残杀威和异丙威两组分

采用速差动力学分光光度法对氨基甲酸脂类杀虫剂残杀威和异丙威进行同时测定，这两种化 的能在碱性条件下水解生成酚盐，进而与对氨基苯酚及高碘酸钾的反应产物醌亚胺发生偶联反应，生成蓝色化合物。反应的速率适中，可用于动力学分析。实验采集了多个时间点下538－700nm间的动力学－吸光度数据，构成量测矩阵，并采用偏最小二乘（PLS）法对量测数据进行解析。本文还对合成样品和环境水样中的残杀威和异丙威含量进行测定，获较好的结果。     

偏最小二乘及双波长K系数光度法同时测定矿物中钛,铁

本文运用化学计量学中的偏最小二乘法及双波长Ｋ系数法实现了Ｔｉ、Ｆｅ的同时测定，方法用于铝钒土及钛铁矿中Ｔｉ、Ｆｅ同时测定，结果满意。     

火焰原子吸收法测定铅锌矿中微量镓

将样品中的硫化物用HNO3氧化为硫酸盐后，再用HNO3、HF、H2SO4进一步溶解，在6mol/LHCl介质中用乙酸丁酯萃取镓，水反萃取后，用火焰析子吸收法测定Ga，该法检出限为0．80μg/mL，相对标准偏差为2．1％，用该法测得国家一级标准品的结果均与推荐值相符。     

催化动力学光度法测定微量钯

在硫酸 ( 1 + 1 )介质中 ,Pd(Ⅱ )催化过氧化氢氧化酸性铬蓝K的褪色反应。研究了反应的最佳条件 ,建立了催化光度法测定痕量钯的新方法。方法的最低检测限为 5 97× 1 0 - 4 μg/mL。线性范围为 5 97× 1 0 - 4 ～ 2 60× 1 0 - 2 μg/mL。该法用于合成样品和含钯催化剂的分析     

植物纤维及其提取物增强聚合物的3D打印成型研究

3D打印技术作为新型成型技术,近年来受到了巨大的关注,但常见的PLA、ABS等单体打印耗材由于其自身的不同缺点,限制了其进一步的应用。本文综述了植物纤维及其提取物增强聚合物复合材料在3D打印领域的应用研究进展,重点阐述了木纤维、竹纤维,秸秆纤维等常见植物纤维用于3D打印的研究现状,还介绍了纤维素、木质素、半纤维素等植物纤维提取物增强聚合物用于3D打印的研究情况。同时对植物纤维/聚合物材料存在的一些问题及改性方法进行了分析与展望。