薯果类维生素C的分光光度法测定

为探讨分光光度测定薯果中维生素C的方法，在待测样品中加草酸处理过滤后于490nm作分光光度测定。结果表明，经分光光度扫描，生成物脎的吸收峰值为488～492nm，温度是测定过程中的重要因素。此法可用于薯果的维生素C测定，较化学方法简便。     

第38届国际化学奥林匹克实验试题

实验1反相色谱分离和分光光度分析用色谱法将物质分离后再进行分光光度分析是一种化学实验室中广泛使用的分析技术。例如,复杂的有机混合物经常用反相液相色谱结合分光光度测定进行分析。反相色谱是利用固定相材料(通常是C18)与被分析物中非极性部分之间的相互作用实现分离的。色谱可以被简化,并且对有兴趣的化合物可通过选择适当的检测波长来选择性地测定。在本实验中,将对经过分离和未经分离的染料进行分光光度分析。1—1混合溶液中R和B的分光光度分析a)测定溶液R(3·02×10-5M)和溶液B(1·25×10-5M)的吸光度,将测定结果填入答卷的表…     

有机试剂结构与性质的研究ⅡDOABS与金属离子反应的研究

应用分光光度法及量子化学方法研究了在表面活性剂存在下,DOABS与Al、Fe(Ⅱ)、Zr(Hf)的配合物组成及反应机理,制定了光度测定这些元素的方法。     

用二甲酚橙作鉈(Ⅲ)的分光光度測定

考布尔(Korbl)及浦希比(Pribil)首先提出二甲酚橙在酸性介质中作为螯合滴定的金属指示剂。巴布柯作了銦-二甲酚橙络合物分光光度研究。布谢夫研究铊(Ⅲ)-二甲酚橙络合物,找出络合物最大吸收在580毫微米及其组成为1:1。我们用二甲酚橙作铊(Ⅲ)的分光光度测定。研究了显色条件,如试剂用量、显色的pH范围、显色时间及络合物祖成等,并提出鎵、銦和鉈(Ⅲ)共存时测定铊的方法。     

用5-Br-PADAP分光光度测定锰的研究

测定微量锰新的分光光度法在文献中并不多。目前惯常分析多用高锰酸钾法,选择性较好,但灵敏度甚低。近几年国外有用吡啶偶氮染料PAN、PAR分光光度测定锰的报导,灵敏度高,选择性欠佳。我们用2-(5-溴-2吡啶偶氮)-5-二乙氨基酚(简称5-Br-PADAP)光度测定锌、镍、铁均以灵敏度高,色泽稳定为特点。用5-Br-PADAP作显色剂分光光度测定微量锰的系统研究似未见报导。本文     

双波长同时分光光度测定合金钢中钨和钼

近年来同时含钨钼的合金钢生产渐增,而光度测定它们会相互干扰,常需先分离或掩蔽。同时分光光度测定是工效高又不分离的有效手段,但钨钼的同时光度测定尚少报道,钢中钨钼的同时光度测定报道更少,且灵敏度也不高。本文则提出一种同时光度测定合金钢中钨和钼的高灵敏     

苯骈-15-冠-5-溴甲酚绿分光光度法测定钠

钠的分光光度测定方法很少。由于冠醚能和碱金属形成稳定的络合物,为分光光度测定钠展示了良好的前景,但到目前为止,利用冠醚分光光度测定碱金属仅集中在钾的测定方法方面,对于钠仅限于络合反应基础研究和分离方面的工作。根据钠的离子直径为1.90A,我们选择了冠醚孔穴直径为1.7到2.2的苯骈-15-冠-5,并配以溴甲酚绿,它们和钠形     

4-(2-噻唑偶氮)-间苯二酚萃取分光光度测定微量钯

用4-(2-噻唑偶氮)-间苯二酚(简称TAR)作分析试剂光度测定金属元素及其在络合滴定中的应用,已有文献报导,但对钯的测定似未见记录。我们实验发现TAR亦为钯的灵敏试剂,在酸性介质中,能与二价钯形成稳定的绿色络合物,易为异戊醇等有机溶剂萃取,灵敏度及选择性均较好。本文实验研究钯-TAR络合物的萃取条件及组成比;并拟定萃取分光光度测定微量钯的方法。     

水杨基萤光酮-溴化十六烷基三甲基铵分光光度法测定钨

在强酸性介质中,水杨基萤光酮与溴化十六烷基三甲基铵能与某些高价金属离子(如钛、钼、钨、锡、锗等)生成稳定的胶束三元络合物。因此,为上述元素提供了分光光度测定的新途径。本文主要研究了以水杨基萤光酮-溴化十六烷基三甲基铵-钨的三元络合体系分光光度测定微量钨的各项条件,并研究了络合物的组成。试验结果表明,本法的灵敏度、选择性以及稳定性均较文献上所记载的其它方法有较大的特点,适合于金属合金材料中钨的快速测定。     

藉铋—亚硝基R盐—结晶紫反应高灵敏分光光度测定痕量铋

本文提出一个超高灵敏测定铋的分光光度方法。     

Spectrophotometric determination of lactic acid

An efficient and inexpensive spectrophotometric method has been developed for the determination of lactic acid in the individual state and in food and biological and cultural liquids. The method is based on the spectrophotometric determination of the colored product of the reaction of lactate ions with iron(III) chloride at 390 nm. The optimum conditions of the reaction have been found, and a calibration curve in the range from 0.3 to 10 g/L of lactic acid with the correlation coefficient 0.9999 has been constructed. The method does not require complex sample preparation.     

New sensitive spectrophotometric method for the determination of clomipramine-HCl in pure form and pharmaceutical preparations

A simple, rapid and sensitive spectrophotometric method for the assay of clomipramine-HCl is described. It has been found that clomipramine-HCl reacts with ammonium molybdate in acetic medium to give blue color product exhibiting maximum absorbance at 712 nm. The reaction is selective for clomipramine-HCl with 1 μg/mL as visual limit of detection. It provides a basis for a sensitive spectrophotometric method for the determination of clomipramine-HCl. The method obeys Beer’s Law from 0.001 to 0.250 mg/mL. The standard deviation does not exceed 0.005 mg/mL. The method has been successfully applied to the determination of clomipramine-HCl in pure form and pharmaceutical preparations. The quantitative assessment of tolerable amounts of possible interferants was also studied. The results are reproduced within ±1% and are in good agreement with those obtained by the standard procedure.     

甲基紫分光光度法测定食盐中的添加剂碘酸钾

研究了碘酸钾、碘化钾与甲基紫在盐酸介质中的显色反应 ,反应产物之最大吸收波长λmax为 650nm ,并由此建立了一个简单、快速、实用的分光光度测定食盐中微量碘酸钾的新方法。在最佳实验条件下 ,碘酸钾质量浓度在 0～ 1 60 μg/ 2 5mL内服从比耳定律 ,其线性相关系数r为 0 .9996。本法用于加碘食盐中微量碘酸钾的测定 ,结果与紫外光度法所得结果基本一致     

乙酰胺的分光光度检测

研究了乙酰胺的分光光度分析方法。该方法用溴水氧化酰胺 ,其氧化产物可把 I-氧化成 I2 ,I2 再和淀粉 -KI生成有色络合物来测定酰胺的含量 ,主要适用于伯酰胺的分析。方法在 5× 1 0 - 6 ～ 1× 1 0 - 4 g/ 2 5m L范围内符合比耳定律 ,表观摩尔吸光系数 ε5 76 nm=4 .5× 1 0 4L·mol- 1·cm- 1。该法灵敏、快速、重现性好。     

A simple spectrophotometric method for the determination of copper in industrial, environmental, biological and soil samples using 2,5-dimercapto-1,3,4-thiadiazole.

A simple spectrophotometric method is presented for the rapid determination of copper at a trace level using 2,5-dimercapto-1,3,4-thiadiazole (DMTD) as a new spectrophotometric reagent. The method is based on the reaction of non-absorbent DMTD in a slightly acidic (0.002-0.014 mol dm(-3) sulfuric acid) aqueous solution with copper(II) to produce a highly absorbent greenish-yellow chelate product that has an absorption maximum at 390 nm. The reaction is instantaneous and the absorbance remains stable for 24 h. The average molar absorption coefficient and Sandell's sensitivity were found to be 5.65 x 10(4) dm3 mol(-1) cm(-1) and 10 ng cm(-2) of CuII, respectively. Linear calibration graphs were obtained for 0.1-20 microg cm(-3) of CuII; the stoichiometric composition of the chelate is 1:2 (Cu:DMTD). A large excess of over 50 cations, anions and complexing agents (e.g. tartrate, oxalate, citrate, phosphate, thiourea, SCN-) do not interfere in the determination. The method was successfully used for the determination of copper in several Standard Reference Materials as well as in some environmental water samples, biological samples, soil samples and solutions containing both copper(I) and copper(II) and complex synthetic mixtures. The method has high precision and accuracy (s = +/-0.01 for 0.5 microg cm(-1)).     

Stability-indicating methods for the determination of disopyramide phosphate

Four methods were developed for the determination of intact disopyramide phosphate in the presence of its degradation product. In the first and second methods, third-derivative spectrophotometry and first derivative of the ratio spectra were used. For the third-derivative spectrophotometric method, the peak amplitude was measured at 272 nm, while for the derivative ratio spectrophotometric method, disopyramide phosphate was determined by measuring the peak amplitude at 248 and 273 nm. Both methods were used for the determination of disopyramide phosphate in the concentration range 12.5-87.5 microg/mL, with corresponding mean recovery 100.8 +/- 0.7% for the first method and 99.9 +/- 0.7% and 99.6 +/- 0.7% for the second method at 248 and 273 nm, respectively. In the third method, an ion selective electrode (ISE) was fabricated using phosphotungstic acid as an anionic exchanger, PVC as the polymer matrix, and dibutylsebacate as a plasticizer. The ISE was used for the determination of disopyramide phosphate in pure powder form in the concentration range 10(-2)-10(-5) M. The slope was found to be 58.5 (mV/decade), and the average recovery was 99.9 +/- 1.6%. The fourth method depended on the quantitative densitometric determination of the drug in concentration range of 0.25-2.5 microg/spot using silica gel 60 F245 plates and ethyl acetate-chloroform-ammonium hydroxide (85 + 10 + 5, v/v/v) as the mobile phase, with corresponding mean accuracy of 100.3 +/- 1.1%. The 4 proposed methods were found to be specific for disopyramide phosphate in presence of up to 80% of its degradation product for the spectrophotometric methods, 90% of its degradation for the densitometric method, and 40% for the ISE method. The 4 proposed procedures were successfully applied for the determination of disopyramide phosphate in Norpace capsules. Statistical comparison between the results obtained by these methods and the official method of the drug was done, and no significant differences were found.     

Novel Spectrophotometric Method for Determination of Macro-paracetamol via Reaction with Bromine

The reaction between Br2 and paracetamol(p-AAP) leads to the formation of a coloured product, which can be used for spectrophotometric determination of the p-AAP content in its pure form and in different pharmaceutical preparations with p-AAP. The stoichiometric composition of the reaction was found to be n(p-AAP)∶n(bromine)=1∶3. The effects of pH and time on the spectra of p-AAP-bromine redox reaction product were studied. The interference of different additives on the measured spectra of the obtained product was also studied. The results obtained by the present method were compared with those obtained by the standard method. The F- and t- test values were calculated for both of the applied procedures and they met a confidence level of 99%. The proposed procedure actually needs no separation of these drugs from their sources before analysis and was unaffected by interference of other phenolic compounds. The proposed method is simpler and faster than the repoeted ones.     

Indirect determination of pepsin activity in human seric protein samples by polyphenol oxidase electrodes

We present a new chronoamperometric methodology for the indirect determination of pepsin activity in proteic solutions. The high-sensitive polyphenol oxidase (PPO) carbon paste bioelectrodes, prepared with 150–200 U of PPO adsorbed on the carbon paste surface and trapped behind a dialysis membrane were able to detect free -tyrosine ( -Tyr) as well as -Tyr-containing peptides, the product of pepsin hydrolysis on haemoglobin samples. The electroactive enzymatic products were determined by their reduction current at −0.050 V, a working potential low enough for preventing electrochemical interferences. The external diffusional barrier posed by the dialysis membrane and the high PPO-superficial concentrations allowed us to prevent electrode surface fouling and to reach stationary diffusional currents after 3 min. The electrochemical -Tyr concentrations measured with proper internal standards, were correlated to those determined by the spectrophotometric reference method (Folin–Ciocalteu), reaching a linear relationship with a slope of 1.05±0.04 and a linear regression coefficient of 0.9951. These results as well as a recovery assay of 98% and the detection limit lower than that of the spectrophotometric method indicate that the proposed methodology is very satisfactory and potentially useful for indirect determination of pepsin in biological samples. The technique was also applied for the determination of pepsin activity in hydrolysed immuno globulin solutions of different composition.     

An improved method of isomolar series by dual-wavelength spectrophotometry

An improved method of isomolar series for determining the composition of an aqueous binary spectrophotometric system is proposed. It is based on the determination by dual-wavelength spectrophotometry of the equilibrium concentration of the chromogenic agent L added in excess, the absorbance of which has been found to be a linear function ofn/m, the composition index of the reaction product M _m L _n in the system, Hence it is a direct and reliable method, applicable also to systems in which the absorption spectra of L and M _m L _n overlap and can be resolved by instrumental masking.     

荷移反应及其在分析化学中的应用 Ⅲ.氟哌酸测定方法研究

本文研究了氟哌酸与四氯对苯醌的荷移反应,确定了反应条件:在硼砂缓冲溶液中形成1:1的络合物,其λ_(max)=375.2nm,表观摩尔吸光系数ε=1.68×10~4·L·mol~(-1)·cm~(-1),应用拟定的方法测定药物制剂含量与文献方法一致,回收率在99％以上,相对标准偏差为1.14％。