A rapid spectrophotometric method for the determination of trace level lead using 1,5-diphenylthiocarbazone in aqueous micellar solutions.

A very simple, ultra-sensitive and fairly selective direct spectrophotmetric method is presented for the rapid determination of lead(II) at ultra-trace level using 1,5-diphenylthiocarbazone (dithizone) in micellar media. The presence of the micellar system avoids the previous steps of solvent extraction and reduces the cost and toxicity while enhancing the sensitivity, selectivity and the molar absorptivity. The molar absorptivities of the lead-dithizone complex formed in the presence of the cationic cetyltrimethylammonium bromide (CTAB) surfactants are almost ten times the value observed in the standard method, resulting in an increase in the sensitivity of the method. The reaction is instantaneous and the absorbance remains stable for over 24 h. The average molar absorption coefficient was found to be 3.99 x 10(5) L mol(-1) cm(-1) and Sandell's sensitivity was 30 ng cm(-2) of Pb. Linear calibration graphs were obtained for 0.06-60 mg L(-1) of Pb(II); the stoichiometric composition of the chelate is 1:2 (Pb:dithizone). The interference from over 50 cations, anions and complexing agents has been studied at 1 mg L(-1) of Pb(II). The method was successfully used in the determination of lead in several standard reference materials (alloys and steels), environmental water samples (potable and polluted), biological samples (human blood and urine), soil samples and solutions containing both lead(II) and lead(IV) and complex synthetic mixtures. The method has high precision and accuracy (sigma = +/-0.01 for 0.5 mg L(-1)).     

A simple spectrophotometric determination of phorate using J-acid

Summary A new and simple spectrophotometric method for the determination of phorate, also known as Thimet, a widely used systemic insecticide is proposed. The method is based on the oxidation of phorate to sulphones by concentrated sulphuric acid and its hydrolysis under acidic conditions at 100°C to release formaldehyde which is then treated with J-acid to produce a yellow fluorescent color, which has an absorbance maximum at 470 nm. Beer's law is obeyed in the range of 1–8 ppm of phorate. The method has been applied to the determination of phorate in effluent water, rice, wheat and cabbage samples. The method is free from interferences of most of the commonly used pesticides and other common ions.     

动力学光度法测定食品中的碘

催化动力学光度法测定痕量碘 ,大多使用Ｃｅ(ＩＶ) -Ａｓ(ＩＩＩ)体系[1 3] 。我们的实验发现在硫酸介质中 ,Ｉ- 能强烈催化高碘酸钾氧化苋菜红的褪色反应 ,在波长 5 2 5ｎｍ处 ,其反应速度与碘离子的浓度之间符合动力学一级反应关系式 ,并且此法灵敏度、选择性均较高。1　实验部分取两支 2 5ｍｌ比色管 ,各加入 2 0ｍｌ浓度为8 0× 1 0 - 3ｍｏｌ/Ｌ苋菜红溶液 ,3 5ｍｌ( 1 0ｍｏｌ/Ｌ)Ｈ2 ＳＯ4,2 0ｍｌＫＩＯ4( 0 2 0ｍｏｌ/Ｌ)溶液。向其中一支加入适量碘标准溶液 ( 1 μｇ/ｍｌ) (吸光度为Ａ) ,另一支不加碘 (吸光度为Ａ0 ) ,用水…     

动力学光度法测定痕量甲醛

在稀硫酸溶液中,甲醛对KClO3氧化罗丹明6G褪色反应有催化作用,研究了其动力学条件,建立了测定痕量甲醛的动力学光度分析方法,线性范围为0.02～1.8μg/mL,检出限为1.5×10-8g/mL。该法用于湖水、饮料和漆料中痕量甲醛的测定,标准加入回收率为93.8%～108.5%,RSD为2.6%～3.4%。     

酸性大红褪色光度法测定痕量铜

研究了在氨 氯化铵介质中铜催化过氧化氢氧化酸性大红的褪色反应及其动力学条件,测定了反应级数和表观活化能,建立了测定痕量铜的新方法。该方法的检出限为6.1×10-3μg/mL,线性范围为0～4.0μg/25mLCu,用于测定水中痕量Cu,结果与原子吸收法的测定结果一致。     

番红花红褪色光度法测定痕量铜

利用铜 ( )对过氧化氢氧化番红花红使其褪色的催化作用 ,建立了分光光度法测定痕量铜的新方法。研究了反应条件 ,测定了反应的级数和表观活化能。该方法的线性范围为 0～ 2 4 0 ng/m L Cu2 + ,检出限为 2 .5× 1 0 -9g/m L。用该法对人发中的铜含量进行了测定 ,结果与原子吸收法一致     

A simple and rapid in situ preconcentration method for trace ammonia nitrogen in environmental water samples using a solid-phase extraction followed by spectrophotometric determination.

A simple and rapid in situ preconcentration method for the spectrophotometric determination of trace ammonia nitrogen in environmental water samples has been developed based on solid-phase extraction using a small column packed with octadecyl group-bonded silica gel (Sep-Pak C18 cartridge). A water sample was taken into a graduated syringe for easy and simple operation and prevention of contamination immediately after sample collection. Ammonia in the sample was reacted with hypochlorite and thymol to be converted into indothymol blue; then the formed indothymol blue was collected as an ion pair between indothymol blue and tetrabutylammonium ion on a Sep-Pak C18 cartridge. The indothymol blue on the cartridge was stable for 4 days. The retained indothymol blue was easily eluted with a mixture of methanol and 0.01 mol/l sodium hydroxide solution. The color intensity due to the indothymol blue was spectrophotometrically measured at 725 nm. The proposed method was successfully applied to environmental water samples such as river water.     

一种简单灵敏的光度法测定环境水样中痕量对苯二酚

在SCN -存在下,控制溶液pH5.0,对苯二酚使Cu(Ⅱ)还原生成的Cu(Ⅰ)与SCN -反应生成CuSCN沉淀,通过测定溶液中剩余Cu(Ⅱ)的量,可以测定对苯二酚的含量.吸光度与对苯二酚含量之间存在良好线性关系.线性方程:A =4.567 +0.9726ρ(μg/mL),线性范围为0.16～4.0μg/mL,相关系...     

A simple spectrophotometric method for the determination of minoxidil

A simple and sensitive method for the determination of minoxidil using 3-methyl-2-benzothiazolinone hydrazone (MBTH) and Fe(III) as the coloring agent is described. The method is sensitive to permit the determination of 0.5–4.5 μg ml⁻¹ of minoxidil at 500 nm. The accuracy and precision of the method were checked by high-performance liquid chromatography.     

催化光度法测定粮食中的痕量锰

研究了测定痕量锰的新催化光度法,方法基于氨三乙酸为活化剂,锰（Ⅱ）催化高碘酸钾氧化溴酚蓝的反应。测定锰的线性范围为0．4－10ng/mL,检出限为0．082ng/mL,对于4.0ng/mL Mn(Ⅱ）的测定,相对标准偏差为3．4％（n=9),其方法已用于粮食中锰的测定。     

氯酸钾体系催化动力学光度法测定痕量钒(Ⅱ)

研究了在0.1 mol/L H3PO4介质中,活化剂抗坏血酸的作用下,V(Ⅴ)催化KClO3氧化甲基红褪色的指示反应,由此建立了一种测定痕量V(Ⅱ)的催化动力学光度新方法。研究了影响该催化褪色反应的因素。方法的线性范围为0.09～7.0 ng/mL,检出限为2.9×10-2 ng/mL。方法用于实际样品的测定。     

催化动力学光度法测定痕量锂

建立了测定痕量Li+的催化动力学光度法。在硼酸缓冲溶液(pH10.0)中,Li+能催化H2O2氧化苋菜红的褪色反应。在540nm波长处,所测得反应体系的吸光度的下降程度与Li+的浓度在0.1~100μg/10 mL间呈线性关系。Li+的检出限为0.3×10-10g/mL,相对标准偏差为1.5%~2.5%,回收率为97.2%~104.5%。方法可用于工业废水Li+检测。     

铌-溴酸钾-偶氮氯膦-mA催化光度法测定痕量铌

在稀H2SO4介质中,铌灵敏催化KBrO3氧化偶氮氯膦 mA的褪色反应,据此建立了催化动力学光度法测定铌的新方法。线性范围为5～30ng mL,检出限0.292ng mL。本法已用于矿石试样中微量铌的测定。     

阻抑动力学光度法测定乳品中的痕量碘

研究了在稀H2SO4介质中,痕量I-对KBrO3氧化酸性品红的阻抑作用及其动力学条件,建立了测定痕量I-的阻抑动力学光度分析的新方法.测定I-的线性范围为0～0.04 μg/mL,检出限为1.1×10-9 g/mL.已用于乳品中痕量碘的测定.     

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     

On-line preconcentration,ion chromatographic separation and spectrophotometric determination of palladium at trace level

A new method for the determination of Pd by ion chromatography and spectrophotometric detection has been developed. The technique is based on the separation of palladium as PdCl4(2-) by anion exchange and on the detection, at a wavelength of 407 nm, of metal as PdI4(2-) after a post-column reaction with KI. The column used was an IonPac AS4 with HCl and HClO4 eluents. The eluent concentration and composition of post-column reagent were optimised in order to obtain the best separation and sensitivity for Pd. In order to reduce the detection limit, an on-line preconcentration step, has been optimised. The method, as developed, was suitable for palladium determination within a 300 ng/l D.L. value. The method applied to a BCR reference material (CRM 277, estuarine sediment) gave satisfactory results in agreement with the certified value within a D.L. value of 1.3 microg/l for the real sample.     

Gravimetric and spectrophotometric determination of mercury with n-benzoyl-n-phenylhydroxylamine

N-Benzoyl-N-phenylhydroxylamine (BPHA) is suggested for the gravimetric determination of mercury(II) at pH 3.0–6.0; the precipitate, Hg(C₁₃H₁₀O₂N)₂, is dried at 105° and weighed. Separation from NH₄⁺, Pb, Bi, Sb, As, Cd, Sn, etc. is possible, but chloride, cyanide and (EDTA) interfere. Mercury(II) can also be extracted with a BPHA solution in chloroform: the extracted mercury complex is yellow and shows an absorbance maximum at 340 mμ. The optimum concentration range for determination is 15–52 μg Hg/ml, the molar extinction coefficient is 2693 ±10 and the sensitivity is 0.075 μg/cm². Interferences are similar to those found in the gravimetric method.     

A simple spectrophotometric method for determination of isoxsuprine hydrochloride in pharmaceuticals

A spectrophotometric method has been developed for the determination of isoxsuprine hydrochloride and its dosage forms, based on its coupling reaction with diazotized sulphanilic acid. The yellow chromophore has an absorption maximum at 440 nm. Beer's law holds over the range 0.8-8 mu/ml in the final solution.     

A simple spectrophotometric determination of endosulfan in river water and soil

Summary A simple spectrophotometric determination of endosulfan (Thiodan), a sulphur containing pesticide is described. The method is based on the liberation of sulphur dioxide from endosulfan which is subsequently absorbed into an absorbing reagent, malonyldihydrazide and estimated by using p-aminoazobenzene and formaldehyde to give a pink coloured dye which has an absorbance maxima at 505 nm. The Beer's law is obeyed in the range of 1–6 ppm for a standard solution of endosulfan. The method can be easily applied in river water and soil samples to determine endosulfan levels as low as 0.05 ppm and 0.25 ppm in river water and soil, respectively. The method is free from the interference of most of the commonly used pesticides and foreign ions.