催化动力学荧光法测定痕量甲醛

在硫酸介质中,甲醛能催化溴酸钾氧化藏红T的反应,使其荧光猝灭,据此建立了催化动力学荧光分析法测定甲醛的新方法。研究了催化反应的性能,优化了方法的实验条件。方法的线性范围为0.025~0.25μg/mL,检出限4.19×10-5μg/mL。该方法简便快速,常见共存物质干扰小,已用于环境水样及家居空气中痕量甲醛的测定,结果满意。     

催化动力学荧光分析法测定啤酒中的痕量甲醛

在稀硫酸溶液中,甲醛催化溴酸钾氧化吖啶红的反应并使其发生荧光猝灭。据此,建立了新的测定痕量甲醛的催化荧光动力学分析法。方法检出限为0.002 mg/L,线性范围为0.004~0.16 mg/L。本法简便、快速,用于啤酒中痕量甲醛的测定,分析结果满意。     

溴酸钾氧化酚藏花红动力学荧光法测定痕量甲醛

在H2SO4介质中,痕量甲醛能显著地催化溴酸钾氧化酚藏花红的反应,使体系的荧光强度减弱,据此建立了动力学荧光法测定甲醛的新方法。在最佳实验条件下,方法的线性范围为8.0～400μg/L,检出限为3.1μg/L。该法简便、快速、选择性好,已用于环境水样中痕量甲醛的测定,其加标回收率在97.5%～103%之间,相对标准偏差为2.9%～3.4%。     

吖啶红荧光法检测Fenton反应产生的羟自由基

提出检测Fenton反应产生羟自由基的方法。羟自由基与吖啶红发生反应后，吖啶红的荧光强度减弱，测定其荧光强度的变化，可间接测定羟自由基的产生量。试验结果表明，△F与吖啶红、硫酸铁及过氧化氢呈量效关系，发现抗氧化剂硫脲清除羟自由基作用呈明显的量效关系，方法稳定性好、操作简便、测定快速，测定了几种辛辣性食品的抗氧化性。     

水发食品中痕量甲醛的测定

为建立催化动力学荧光法测定痕量甲醛的新方法,基于在酸性介质中,甲醛催化KBrO3氧化藏红T的褪色反应,使其荧光猝灭的原理,将反应体系在沸水浴中加热8 min,流水冷却3min,采用动力学荧光法测定痕量甲醛。结果表明,甲醛在0.02~0.14μg/mL范围内与△F值呈良好的线性关系,线性方程为△F=-1.642 8+274.12C(μg/mL),r=0.996 9,检出限为0.011μg/mL。该法简便,快速,常见共存物质干扰小,可用于水发食品及其它食品中甲醛含量的测定,加标回收率为84.63%~94.93%。     

催化荧光动力学法测定食品中痕量甲醛

基于在酸性条件中,甲醛催化KBrO3氧化吡口罗红B的褪色反应,使其荧光猝灭,建立了荧光动力学法测定痕量甲醛的新方法。反应在沸水浴中进行8 min,测定甲醛的线性范围为0.016~0.14 mg/L,检出限为8.6×10-6g/L。该方法用于水发食品中甲醛的测定,并进行了加标回收试验,回收率在96.0%~104.2%之间,相对标准偏差为1.7%~3.5%。     

吖啶红催化动力学光度法测定痕量亚硝酸根

１引言测定痕量亚硝酸根，光度法仍是最重要的一类方法，但常规光度法如Ｇｒｉｅｓｓ法等灵敏度较低，而另一系列基于通过ＮＯ－２的重氮化和偶联反应，形成偶氮染料的光度法，均需使用有毒试剂。在稀磷酸溶液中，ＮＯ－２对ＫＢｒＯ３氧化吖啶红（Ａｃｒｉｄｉｎｅｒｅｄ，Ｃ．Ｉ．４５０００，缩写为ＡＤＲ）的褪色反应具有很强的催化作用，以此反应为指示反应，建立了测定痕量ＮＯ－２的新方法，用于多种样品中ＮＯ－２的测定，结果满意。２．２实验部分２．１仪器及试剂澳大利亚ＧＢＣＵＶ／ＶＩＳ９１６分光光度计（带恒温比色架），Ｔ…     

动力学荧光法测定痕量对苯二酚的研究

在稀H2SO4介质中,痕量对苯二酚对V(Ⅴ)催化KIO4氧化吡啰红Y的反应具有显著的阻抑作用,据此建立了动力学荧光法测定痕量对苯二酚的新方法。研究了体系的动力学条件,考察了各种因素的影响。方法的线性范围为0.01～2.5mg/L,检出限为0.006mg/L。该方法用于水样中对苯二酚的测定,加标回收率在98.8%～101.6%之间,相对标准偏差为2.5%～2.9%。     

催化动力学荧光法测定洋葱中的槲皮素

研究了稀硫酸介质中,槲皮素催化溴酸钾氧化吖啶红的荧光光谱。在优化实验条件下,确定了荧光强度改变值(ΔIF)与槲皮素质量浓度的关系,建立了催化动力学荧光法测定洋葱中槲皮素的新方法。该方法的线性范围为0.43~18.0μg.L-1,检出限为0.13μg.L-1。方法操作简便,具有较好的灵敏度,用于洋葱中槲皮素含量的测定,结果满意。     

环境样品中痕量甲醛的催化荧光动力学分析

基于在硫酸介质中, 痕量甲醛能促进溴酸钾氧化吡咯红并使其荧光强度减弱的反应, 建立了动力学荧光法分析测定痕量甲醛的新方法. 研究了温度、时间, 各种试剂浓度等条件对测定的影响. 在最佳实验条件下, 方法的线性范围是8～200 ng/mL, 检出限为6.1 ng/mL. 该方法用于环境水样、室内空气、食品中痕量甲醛的测定, 并与乙酰丙酮分光光度法进行了对照, 结果无显著性差异.     

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%。     

Kinetic spectrophotometric method for rapid determination of trace formaldehyde in foods

A simple and sensitive kinetic-spectrophotometric method was developed for the determination of ultra trace amount of formaldehyde in food samples. The method was based on the oxidation of rhodamine B (RhB) by potassium bromate in sulfuric acid medium (formaldehyde as catalyst). The reaction was monitored by measuring the decrease in absorbance of the dye at 515 nm after 6 min. The developed method allowed the determination of formaldehyde in the range of 10–100 μg L⁻¹ with good precision, accuracy and the detection limit was down to 2.90 μg L⁻¹. The relative standard deviations for the determination of 10 and 60 μg L⁻¹ of formaldehyde were 3.0% and 1.9% (n = 10), respectively. The method was found to be sensitive, selective and was applied to the determination of formaldehyde in foods with satisfactory results.     

Fe_3O_4磁性纳米粒子催化动力学荧光法测定微量过氧化氢

Fe3O4磁性纳米粒子(Fe3O4MNPs)具有模拟过氧化氢酶的催化特性。基于Fe3O4MNPs催化H2O2氧化吡罗红建立了催化动力学荧光法测定H2O2的方法。对Fe3O4MNPs-吡罗红-H2O2体系的荧光光谱进行了研究,并考查了一些因素对体系的影响。所研究的催化反应分别在7~13min和13~18min内为假零级反应,对应的表观速率常数分别为1.33×10-1s-1和8.41×10-2s-1。反应时间为18 min时,催化反应的表观活化能为40.42 k J·mol-1。在最佳实验条件下,方法的线性范围为3.20×10-4~1.12×10-2mol·L-1,检出限为1.65×10-4mol·L-1。该法可用于消毒液、雨水、自来水及合成样品中H2O2含量的测定。     

Determination of Formaldehyde Traces in Fabric and in Indoor Air by a Kinetic Fluorimetric Method

A simple and sensitive kinetic fluorimetric method is reported for the determination of trace amount of formaldehyde. The proposed method is based on the catalytic effect of formaldehyde on the oxidation reaction of rhodamine B with potassium chlorate in sulfuric acid solution. Formaldehyde in the range of 0.020-0.340 µg/mL can be determined with a limit of detection of 5.73 ng/mL. The method has been used to determine trace formaldehyde in fabric and in indoor air. The results thus obtained show good agreement with those determined by acetyl acetone method.     

乙基橙-溴酸钾体系动力学光度法测定痕量甲醛

研究了在稀H2SO4介质中,痕量甲醛催化KBrO3氧化乙基橙褪色反应的适宜条件和影响因素,建立了测定痕量甲醛的动力学光度法。方法采用固定时间法于507 nm波长处测量体系的吸光度,在适宜条件下,ΔA与甲醛质量浓度具有良好的线性关系,方法的线性范围为0~0.24 mg/L,检出限为0.004 mg/L。该方法用于饮料、废水和废气中痕量甲醛的测定,测定结果的相对标准偏差RSD≤3%(n=6),回收率为102%。     

Kinetic spectrofluorimetric determination of certain cephalosporins in human plasma

An accurate, reliable, specific and sensitive kinetic spectrofluorimetric method was developed for the determination of seven cephalosporin antibiotics namely cefotaxime sodium, cephapirin sodium, cephradine dihydrate, cephalexin monohydrate, cefazoline sodium, ceftriaxone sodium and cefuroxime sodium. The method is based on their degradation under an alkaline condition producing fluorescent products. The factors affecting the degradation and the determination were studied and optimized. The reaction is followed spectrofluorimetrically by measuring the rate of change of fluorescence intensity at specified emission wavelength. The initial rate and fixed time methods were used for the construction of calibration graphs to determine the concentration of the studied drugs. The calibration graphs are linear in the concentration ranges 0.2-1.2 μg mL⁻¹ and 0.2-2.2 μg mL⁻¹ using the initial rate and fixed time methods, respectively. The results were statistically validated and checked through recovery studies. The method has been successfully applied for the determination of the studied cephalosporins in commercial dosage forms. The high sensitivity of the proposed method allows the determination of investigated cephalosporins in human plasma. The statistical comparisons of the results with the reference methods show an excellent agreement and indicate no significant difference in accuracy and precision.     

Spectrofluorimetric determination of formaldehyde in air after collection onto silica cartridges coated with Fluoral P

In the present work, a sensitive and selective fluorimetric method for formaldehyde determination in air samples is described. The method is based in the reaction between formaldehyde and Fluoral P producing 3,5-diacetyl-1,4-dihydrolutidine, which, when excited at 410 nm, emits fluorescence at 510 nm.The Fluoral P was prepared by the reaction of 0.3 ml of acetic acid, 0.2 ml of acetylacetone and 15.4 g of ammonium acetate. Then, the volume was completed to 100 ml with deionized water. The Fluoral P obtained, if stored under refrigeration in the dark, can be used, safely, for 60 days.The calibration curve obtained with concentrations of formaldehyde in the range of 12 to 192 ng ml⁻¹ (n=9) was Intensity=1.11C+0.06 (R²=0.9920). In the quantification of formaldehyde, air samples were passed at 1 l min⁻¹, during 120 min, through glass impingers containing 40 ml of Fluoral P, followed by direct fluorescence measuring, or through two SEP PAK silica cartridges, coated with Fluoral P. The cartridges were eluted with 10 ml of Fluoral P solution and quantified by spectrofluorimetry. Under these conditions, the detection limit (S/N=3) obtained was 2.0 ng ml⁻¹.The new methodology was validated by comparison with a well-known HPLC method in which formaldehyde was collected into SEP PAK C18 cartridges coated with 2,4 dinitrophenylhydrazine. The application of the t_95% test did not show significant differences between the HPLC and either fluorimetric methodologies.This method has been used in the determination of gas phase formaldehyde in both indoor and outdoor sites. For the indoor site, the measured concentrations were in the range of 9.0 to 67.7 μl l⁻¹, while for the outdoor site they were in the range of 16.8 to 38.8 μl l⁻¹. Further, due to the ease of handling in field studies, the SEP PAK cartridges coated with Fluoral P were used. The formaldehyde concentrations thus determined, in outdoor sites, were in the range of 2.09 to 25.1 μl l⁻¹. The main advantage of this analytical procedure is its selectivity for formaldehyde, without interferences from bisulfite and other aldehydes, especially acetaldehyde, and low blank level, resulting in low detection limits. In addition, very little sample preparation is required.     

吖啶红-SLS体系共振瑞利散射法测定蛋白质

研究了吖啶红染料与蛋白质的结合反应。在十二烷基磺酸钠存在下及pH2.90的柠檬酸NaOH介质中,蛋白质与吖啶红形成复合物,使最大波长392nm的共振光散射光谱得到加强,根据其共振光散射的增强程度,可用于蛋白质的定量测定。十二烷基磺酸钠的加入,使灵敏度提高11倍,牛血清白蛋白、γ球蛋白的线性范围分别为0.03～0.7mg/L、0.05～1.3mg/L,检出限分别为6.4μg/L、10.8μg/L。用于人血清、牛奶、豆浆、尿液中总蛋白质的测定,结果与经典的考马斯亮蓝G 250法一致。