过氧化氢氧化灿烂甲酚蓝动力学光度法测定痕量铝

基于pH3.6的乙酸 乙酸钠缓冲介质中Al3 对过氧化氢氧化灿烂甲酚蓝(BCB)褪色反应的催化作用,提出了测定痕量铝的新的催化动力学光度法。研究了该法的适宜反应条件,方法的线性范围为0～100ng mL,检出限为0.9ng mL。方法已用于样品中痕量铝的测定。     

Co2+与BPPT络合反应动力学及动力学光谱法测定钴

Thiosemicarbazones and phenylthiosemicarbazones are in- teresting ligands because of their ability to form highly stable and intensely colored complexes, which is attributed to the for- mation of bond between sulfur and hydrazino nitrogen atoms, and these…     

Co2+与BPPT络合反应动力学及动力学光谱法测定钴

Kinetics of complexation reaction of Co2+ with 2-benzoylpyridine-4-phenyl-3-thiosemicarbazone (BPPT)was spectrophotometrically examined at 421 nm. The ligand that is developed for a simple kinetic-spectrophotometric determination of Co2+ is based on 1:2 complex formation between Co2+ and BPPT. The complexation reaction was carried out in ethanol-water medium at 25 ℃. Kinetic and activation parameters of the complexation reaction were calculated, and the rate equation and the reaction mechanism were proposed. The calibration graph is linear in the concentration range of 0.10～2.91 mg·L-1 for the tangent method. The species that caused interference were investigated.     

Kinetic Spectrophotometric Determination of Ascorbic Acid in Pharmaceutical Samples by Oxidation of Ponceau 4R by Hydrogen Peroxide

A new sensitive and simple kinetic method is developed for determination of traces of ascorbic acid based on its activated effect on oxidation of trisodium‐2‐hydroxy‐1‐(4‐sulphonato‐1‐naphthylazo)naphthalene‐6,8‐disulphonato (red artificial color Ponceau 4R) by hydrogen peroxide, in the presence of Cu(II) as catalyst, in borate buffer. The reaction is followed spectrophotometrically by tracing the oxidation product at 478.4 nm within 1 min after addition of H₂O₂. The optimum reaction conditions are: borate buffer (pH = 11.00), Ponceau 4R (9.6·10^?6 mol/L), H₂O₂ (2·10^?2 mol/L), Cu(II) (8·10^?7 mol/L) at 22 °C. Following this procedure, ascorbic acid can be determined with a linear calibration graph up to 1.76 ng/mL and a detection limit of 0.28, based on 3S criterion. The relative error ranges between 6.77‐1.66% for the concentration interval of ascorbic acid 1.76‐17.61 ng/mL. The effects of certain foreign ions upon the reaction rate were determined for an assessment of the selectivity of the method. The method was applied for determination of ascorbic acid in pharmaceutical samples, and spectrophotometric method was used like an comparative method.     

过氧化氢氧化桑色素动力学荧光法测定痕量钴(Ⅱ)

建立了以Co(Ⅱ)为催化剂,催化过氧化氢氧化桑色素,使其荧光减弱的催化动力学荧光法。在pH 10.70的Na2B4O7?10H2O - NaOH缓冲溶液中,痕量钴(Ⅱ)离子对0.24%的H2O2溶液氧化 4.0×10-7 mol/L的桑色素溶液有明显的催化作用。在最大波长处( λex/λem = 416.5 nm / 556.4 nm),体系的荧光强度在一定的浓度范围内与Co(Ⅱ)的浓度呈线性相关,线性范围为0.8～8.0 μg/L,检出限为0.14 μg/L。优化了体系的最佳条件,考察了体系的离子干扰情况,对灰钙土和分子筛样品进行了分析检测,回收率分别为95.0～110.0%和98.9%～101.9%。     

Kinetic Determination of Iodide Based on its Effect on the Hydrogen Peroxide Oxidation of Triflupromazine

Summary.  A new selective, sensitive, and simple kinetic method is developed for the determination of trace amounts of iodide. The method is based on the catalytic effect of iodide on the reaction of triflupromazine (TFP) with H₂O₂. The reaction is followed spectrophotometrically by tracing the oxidation product at 498 nm within 1 min after addition of H₂O₂. The optimum reaction conditions are TFP (0.4 × 10⁻³ M), H₂SO₄ (1.0M), H₃PO₄ (2.0M), and H₂O₂ (1.6M) at 30°C. Following this procedure, iodide can be determined with a linear calibration graph up to 4.5 ng ċ cm⁻³ and a detection limit of 0.04 ng ċ cm⁻³, based on the 3 S_b criterion. The method can also be applied to the determination of iodate and periodate ions. Determination of as little as 0.2, 1.0, 2.0, and 4.0 ng ċ cm⁻³ of I⁻, IO₃ ^-, or IO₄ ^- in aqueous solutions gave an average recovery of 98% with relative standard deviations below 1.6% (n = 5). The method was applied to the determination of iodide in Nile river water and ground waters as well as in various food samples after alkaline ashing treatment. The method is compared with other catalytic spectrophotometric procedures for iodide determination. Received January 19, 2001. Accepted (revised) March 12, 2001     

Kinetic method for acetylsalicylic acid determination based on its inhibitory effect upon the catalytic decomposition of H<Subscript>2</Subscript>O<Subscript>2</Subscript>

The catalytic reaction of catalase was investigated, by means of a Clark oxygen sensor, in the presence of various concentrations of acetylsalicylic acid. Michaelis-Menten kinetic parameters were determined from Lineweaver-Burk plots, obtained in the absence and in the presence of the inhibitor. The inhibition pattern, suggested by the Lineweave-Burk plots, corresponds to a fully mixed inhibition mechanism. A kinetic method, based on the indicator reaction: , was developed for the quantitative determination of acetylsalicylic acid. Calibration graphs of the reciprocal value of first-order rate constant versus acetylsalicylic concentration covered the concentration range (2.99–19.98)×10^–4 mol/L, while the detection limit was 4.12×10^–4 mol/L acetylsalicylic acid with a standard deviation of 2.1×10^–5 mol/L.     

Review: Current Development of Immunoassay for Analyzing Veterinary Drug Residue in Foods and Food Products

Veterinary drug residues in foods and food products have been reported to be harmful for consumer health and must not be permitted in food intended for human consumption. These drugs include antibiotics, anthelmintics, beta-receptor agonists, and steroids. Immunoassay is recognized as the most powerful screening technique for a large number of different compounds. Because of the rapidity, sensitivity, and cost-effectiveness of this method, numerous immunoassays have already been developed for screening purposes to reduce sample loading for conventional analysis. In this review, the principles and an overview of advanced immunoassays for various veterinary drugs will be given.     

催化动力学电位法测定甲醛

基于硫酸介质中，甲醛对溴酸钾氧化碘化钾的促进作用，用碘离子选择电极跟踪Ⅰ^-，建立了测定微量甲醛的动力学电位法。方法的线性范围为0～5mg/L，检出限为0．055mg／L。利用此法测定了废水和空气中的甲醛含量，结果满意。     

Kinetic determination of organosulphur ligands by inhibition: Trace determination of cysteine and maleonitriledithiolate (MNDT)

Some organosulphur ligands have been found to inhibit the mercury(II) catalyzed substitution of cyanide in hexacyanoferrate(II) by N-methylpyrazinium ion (Mpz⁺). The inhibitory effect is due to the binding tendency of catalyst Hg²⁺ with these inhibitors. This effect has been used as a basis to develop a kinetic method for the determination of trace amounts of two organosulphur ligands viz. cysteine and MNDT. The reaction was followed spectrophotometrically at 655 nm by measuring the decrease in absorbance of the product [Fe(CN)₅Mpz]²⁻. The influence of the reaction variables has also been studied. A general mechanistic scheme of the indicator reaction system including the role of inhibitor has been proposed and applied to determine the organosulphur ligands. Under the selected experimental conditions cysteine and MNDT have been determined in the range of 2–20 × 10^− 7 M and 5 × 10^− 8 M to 12 × 10^− 7 M respectively in various aqueous samples. The analytical concentration range depends upon the amount of Hg²⁺ present in the indicator reaction and also on the stability of the Hg²⁺-inhibitor complex in question. Under specified conditions, the detection limit for cysteine and MNDT are 2 × 10^− 7 M and 5 × 10^− 8 M respectively. The influences of possible interference by major amino acids, on the determination of cysteine and their limits have been investigated.     

催化动力学光度法测定微量钴的研究

在ｐＨ＝４．０的ＨＡｃ－ＮａＡｃ介质中，在避光条件下，钴对无色的Ｆｅ（Ⅲ）－联吡啶配合物还原成红色的Ｆｅ（Ⅱ）－联吡啶配合物有较强的催化作用。据此本文建立了微量钴的新催化动力学光度法，对钴的线性范围为０～１．０μｇ／ｍＬ Ｃｏ，检测限为０．０１８μｇ／ｍＬ。本法选择性较好，多数离子均允许大量存在。本法测定了维生素Ｂ１２及分子筛中的钴，获得满意的分析结果。并对钴的催化机理作了初步探讨。     

兽药残留分析中样品前处理技术研究进展

样品前处理是兽药残留分析中的关键步骤,直接影响检测的结果.近年来,出现了一些新的样品前处理技术,如固相萃取、基质固相分散萃取、固相微萃取、搅拌棒吸附萃取、膜萃取、液相微萃取、超临界流体萃取、加速溶剂萃取、分子印迹、微波辅助萃取.这些技术能够有效地减少分析过程中由样品前处理过程带来的误差,具有前处理快速、简便的优点,同时可与分析仪器联用,实现分析的自动化.本文对这些新技术的基本原理、特点及在兽药残留分析中的应用进行了综述,并对样品前处理的前景进行了展望.     

Kinetic Spectrophotometric Determination of Thiols and Ascorbic Acid

Abstract

This paper describes a kinetic spectrophotometric method for the determination of L‐ascorbic acid (AA) and thiols (RSH). Absorbance of Fe(II)‐phen complex formed during the reaction of AA or RSH with Fe(III)‐phen was continuously measured at 510 nm by double‐beam spectrophotometer with flow cell. For determination some thiols, the catalytic effect of Cu²⁺ ions was used. AA and RSH can be determined in concentration ranges from 4.0×10^?6 to 4.0×10^?5 M and from 8.0×10^?6 to 8.0×10^?5 M, respectively. The applicability of the proposed method was demonstrated by determination of chosen compounds in pharmaceutical dosage forms.     

Spectrophotometric Determination of Hydrogen Peroxide Using Leucocrystal Violet in Micellar Medium

A simple and sensitive spectrophotometric method for the determination of hydrogen peroxide, based on the increase in color intensity of dye on addition of surfactant, is described. Hydrogen peroxide is first reacted with potassium iodide in acidic medium, in presence of ammonium molybdate to liberate iodine. The liberated iodine oxidizes leucocrystal violet to crystal violet having maximum absorbance at 593 nm. The color of the dye intensifies with the addition of the surfactant, cetyl pyridinium chloride though the absorption maximum remains the same. Beer's law is obeyed in the range 0.05–0.45 µg of hydrogen peroxide per 25 mL of final solution (0.002–0.018 µg mL^?1) with an excellent correlation coefficient (r = 0.9977). The proposed method has been successfully applied for the analysis of hydrogen peroxide in various food products and rainwater.     

动力学光度法测定食品中痕量甲醛

基于酸性介质中甲醛抑制KBrO3氧化碱性品红的褪色反应,建立了阻抑动力学光度法测定痕量甲醛的新方法.利用固定时间法优化了试剂浓度、反应时间和反应温度.在所选择的实验条件下,方法的线性范围为0.08～1.0 mg·L-1,检出限为0.015 mg·L-1.该方法用于水发食品中甲醛含量的测定,并进行了加标回收试验,回收率在93%～105%之间.     

Kinetic approach for evaluation of total antioxidant activity

We propose a novel approach for assessment of total antioxidant activity by monitoring kinetics of hydrogen peroxide (H₂O₂) scavenging after its injection into liquid sample under study. H₂O₂ is known to be the strongest oxidant, really presented in human body in contrast to the majority of the model oxidative systems used for evaluation of antioxidant activity. In addition, kinetic approach, being more informative than the commonly used determination of the final product, obviously provides better discrimination of potential antioxidants. Prussian Blue based sensor due to its high sensitivity and operational stability allowed to monitor kinetics of hydrogen peroxide consumption in turbid and colored samples. The pseudo-first order kinetic constants of hydrogen peroxide scavenging in the presence of different food additives correlated with total antioxidant activity of these samples evaluated via standard procedure based on lipid peroxidation. However, in contrast to the standard method, the proposed kinetic approach is expressed and does not require fresh biological tissues.     

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.     

三氮烯类试剂在表面活性剂分析中的应用

对近年来三氮烯类试剂在测定阴离子表面活性剂、阳离子表面活性剂光度分析中的应用进行了综述,引用文献25篇。     

KIO_4－NTA－二苯胺磺酸钠体系催化光度法测定痕量锰（Ⅱ）

本文研究了Ｍｎ（Ⅱ）催化ＫＩＯ＿４氧化二苯胺磺酸钠的显色反应。在ＮａＡｃ－ＨＣｌ介质中，以氨三乙酸作活化剂，当测定波长为５１０ｎｍ时，锰浓度在０～１５０ｎｇ／２５ｍＬ范围内与吸光度呈线性关系。该法已用于测定茶叶、莲子、黄豆等样品中的痕量锰，结果个人满意。