Applications of enzyme-catalysed reactions in trace analysis--I. Determination of mercury and silver by their inhibition of invertase

Procedures are described for the accurate determination of silver (2-10 x 10(-7)M) and mercury(II) (2-10 x 10(-7)M) in the presence of each other and of most other metals. The methods are based on the inhibition by these metals of invertase catalysis of the hydrolysis of sucrose.     

Applications of enzyme-catalysed reactions in trace analysis-VI Determination of mercury and silver by their inhibition of yeast alcohol dehydrogenase

The inhibition of yeast alcohol dehydrogenase is applied to the determination of 2-200 ng of mercury(II) and 1-100 ng of silver. The enzyme, when used to catalyse the oxidation of ethanol, or the reverse reaction, is equally sensitive to inhibitors.     

Applications of enzyme-catalysed reactions in trace analysis-VII Determination of lead and indium by their inhibition of isocitrate dehydrogenase

The inhibition of isocitrate dehydrogenase by lead, indium and calcium has been studied. Methods for the determination of 0.024-1 mug of lead and indium, based on this inhibition, are outlined. Lead may be separeted from some interfering ions by extraction with tributyl phosphate in isobutyl methyl ketone, before application of the enzymic reaction.     

Applications of enzyme-catalysed reactions in trace analysis-IV Determination of beryllium and zinc by their inhibition of calf-intestinal alkaline phosphatase

Methods are described for the determination of beryllium (18-90 ng) and zinc (0.6-6 mug), based on their inhibition of calf-intestinal alkaline phosphatase.     

Applications of enzyme-catalysed reactions in trace analysis-II Determination of cyanide, sulphide, and iodine with invertase

Methods are described for the determination of cyanide (10⁻⁸–10⁻⁵M and sulphide (10⁻⁷–10⁻⁵ M) based on the de-inhibitory effect of these ions on invertase inhibited by mercury(II) or by silver. Iodine (0.1–3 μg) may be determined by its inhibition of invertase.     

Applications of enzyme-catalysed reactions in trace analysis-V Determination of zinc and calcium by their activation of the apo-enzyme of calf-intestinal alkaline phosphatase

The activation of the apo-enzyme of calf-intestinal alkaline phosphatase by zinc in the presence and absence of magnesium 4 x 10(-4)M) is applied to the determination of 6-65 ng and 65-650 ng of zinc, respectively. The activation of the apo-enzyme by calcium in the presence of 1.4 x 10(-7)M zinc is used to determine 1-4 mug of calcium. The mechanism of the re-activation effects is discussed.     

阻抑动力学光度法测定痕量尿素

研究了在酸性介质中,痕量尿素对NO2-催化KBrO3氧化维多利亚绿G的阻抑作用,通过测量617 nm处吸光度的变化,建立了测定痕量尿素的阻抑动力学光度分析的新方法。在最佳实验条件下,测定尿素的线性范围为0.0~0.14mg/L,检出限为5.0×10-6g/L。对2.0μg/25 mL进行10次平行测定的相对标准偏差为2.8%。并试验了共存离子对催化反应的影响,常见的离子均不干扰测定。方法可用于废水中痕量尿素的测定。     

阻抑-褪色光度法测定痕量间苯二酚

在NH3 NH4Cl介质中 ,间苯二酚能阻抑Fe(Ⅲ )为催化剂 ,邻菲罗啉为活化剂的过氧化氢氧化甲酚红的褪色反应。研究了该反应的最佳条件和动力学参数。建立了一种测定痕量间苯二酚的新方法。方法检出限为 3 5× 1 0 - 4 g·L- 1 ,测定范围为 0 .30mg/L～ 7.0mg/L ,方法可用于废水中间苯二酚的测定     

银纳米粒子共振光散射光谱法测定痕量CTMAB

利用十六烷基三甲基溴化铵(CTMAB)与银纳米粒子作用生成的聚集体,使体系的共振光散射(RLS)强度明显增强,建立了一种快速、简便的测定痕量CTMAB的RLS光谱法。考察了p H值,反应最佳时间,试剂加入顺序等因素对测定CTMAB的影响。实验结果表明,在p H值为10.88,作用时间为10 min,银纳米粒子浓度(以银原子计算)为2.5×10-3mol·L-1,按CTMAB、BR、银纳米粒子为添加顺序的条件下,测定CTMAB的线性范围为:5.0×10-9~5.0×10-7mol·L-1,检出限为3.8×10-9mol·L-1。该法用于合成样品中CTMAB的测定,灵敏度高,重现性好,结果准确。     

阻抑动力学分光光度法测定痕量碘

研究了在稀H3PO4介质中,痕量碘离子对NO-2催化溴酸钾氧化吖啶橙的阻抑作用,建立了测定痕量碘离子的阻抑动力学光度分析的新方法。测定碘离子的线性范围为0～0.40μg/mL,检出限为7.3×10-9g/mL。已用于食品中的微量碘的测定。     

饮用水中痕量银的聚合物改性硅胶固相萃取-火焰原子吸收光谱法测定

研究了以聚异丁烯-alt-马来酸酐和L-半胱氨酸改性硅胶固相萃取-原子吸收光谱法(SPE-FAAS)测定饮用水中痕量银的方法;考察了样品pH、进样体积、流速,以及洗脱剂种类、浓度、体积、流速等参数对萃取率的影响,同时研究了共存离子的影响,评价了萃取材料的吸附容量及再生性能.结果表明,在优化的实验条件下,该法的检出限(3σ)为1.5μg.L-1,相对标准偏差(RSD)为2.9%(c=20μg.L-1,n=7),富集倍数为18.7.该法可成功地用于测定井水、自来水、纯净水等水样中的痕量银.     

Determination of major components and trace elements in ancient silver by thermal neutron activation analysis

Thermal neutron activation of minute samples of ancient silver objects has provided useful information concerning their silver, copper and gold content. The results of such analysis of eighteen Sasanian silver objects are discussed together with consideration of the sampling problems involved. In order to extend these measurements to include other elements, an isotopic exchange system has been developed to separate other activities present in irradiated silver specimens quantitatively from the silver, copper and gold activities. Following exchange with cuprous and silver iodides it has been possible to count quantitatively the activity of fourteen additional elements: As, Br, Co, Cr, Fe, Hg, Ir, K, Mn, Na, Sb, Sc, Se and Zn. Research supported in part by the U. S. Atomic Energy Commission.     

Determination of mercury(II) by invertase enzyme inhibition coupled with batch injection analysis

The determination of mercury(II) ions at the trace level by inhibition of the invertase enzyme-catalysed hydrolysis of sucrose into glucose and fructose coupled to electrochemical batch injection analysis was investigated using two approaches. In the first, the glucose produced was detected by injection of 100 microliters samples into the batch injection cell containing a platinum electrode modified by immobilised glucose oxidase. In the second, the glucose and fructose present in injected samples were oxidised directly at a copper-modified glassy carbon electrode. The experimental parameters were optimised and the degree of enzyme inhibition by mercury(II) ions under both conditions was measured. Mercury concentrations in the ng ml-1 range were determined by these two techniques with low sample and reagent consumption. Comparison is made between the two methods and perspectives as a screening test for field application are indicated.     

CdTe量子点荧光猝灭法测定奥沙利铂中微量银

以谷胱甘肽作为稳定剂,100℃恒温回流,直接合成水溶性CdTe量子点。基于Ag+对合成的CdTe量子点的荧光猝灭效应,建立了测定抗癌药物奥沙利铂中微量银的方法。考察了量子点浓度、缓冲液种类、缓冲液浓度、缓冲液pH和反应时间对银离子测定的影响。当量子点浓度为0.004 g/L时,在0.10 mmol/LpH7.4的磷酸缓冲溶液中,反应时间为5 min,体系的相对荧光强度与Ag+的质量浓度呈良好的线性关系,其线性范围为16.42～98.50μg/L,线性相关系数为0.9975,检出限为0.12μg/L。     

二苯硫脲-醋酸丁酯萃取-石墨炉原子吸收法测定地球化学样品中痕量银

对石墨炉原子吸收光谱法测定地球化学样品中痕量银进行了研究。样品经盐酸、硝酸、硫酸、高氯酸溶解,在盐酸(1.2mol/L)介质中用醋酸丁酯萃取银与二苯硫脲螯合物,用石墨炉原子吸收光谱法测定地球化学样品中痕量银,方法检出限为0.011ng/mL,相对标准偏差(RSD,n=11)为6.0%~12.2%,加标回收率为96.00%~105.00%。能满足地球化学样品中银含量为0.02~5μg/g范围内银测定的准确度和精密度的要求。     

Determination of silver, gold and palladium by a combined fire-assay atomic-absorption procedure

A method is described which combines the best features of the fire-assay procedure with an atomic-absorption technique. The precious-metal bead resulting from the fire-assay concentration step is dissolved in acids, the solution evaporated to dryness and the residue dissolved in b measured quantity of cyanide solution. The atomicabsorption measurement of this solution allows the determination of as little as 0.017 ppm of silver, 0.08 ppm of gold, and/or 0.08 ppm of palladium in various precious-metat-bearing materials with a precision of +/- 1%.