KINETIC SPECTROPHOTOMETRIC DETERMINATION OF TRACE AMOUNT OF EUROPIUM BASED ON ITS INHIBITORY EFFECT OF THE OXIDATION OF SWITZERLAND PIGMENT BY POTASSIUM BROMATE

In 4.0 × 10^?3 mol/L of hydrogen chloride medium, a trace of europium(III) plays a good inhibitory role in the fading reaction of Switzerland pigment oxidized by potassium bromate. Based on this principle, an inhibitory kinetic spectrophotometric method for the determination of trace europium was developed. A maximum absorption wavelength locates at 600 nm and a good linear range is presented over 0 – 0.18 µg/mL of europium(III) under the optimum conditions. The regression equation for the determination of europium(III) is ΔA = 4.495C(C:μg/mL) + 0.0278 with a correlation coefficient of 0.9965. The detection limit of the method was 19 ng/mL. The apparent activation energy of the inhibitory reaction and the reaction half-life period were 5.76 KJ/mol and 15.61 min, respectively. This method has been successfully used in the determination of europium in molecular sieve samples.     

同位素示踪法研究~(125)Ⅰ-NGF在小鼠体内的吸收、分布及排泄

本文应用放射性同位素示踪法与电泳分离法相结合的方法研究125I-NGF在小鼠体内的吸收、分布和排泄。结果显示:静脉注射和肌肉注射125I-NGF在小鼠体内的代谢规律均符合二房室开放模型。肌肉注射10μg/kg,20μg/kg,40μg/kg 3个剂量达峰时间分别为0.71h,1.66h,3.78h;峰浓度分别为1.74ng/mL,2.82ng/mL,4.23ng/mL;曲线所围面积分别为8.44μg/h/L,21.6μg/h/L,43.12μg/h/L,消除相半衰期分别为4.83h,4.49h,4.43h。肌肉注射10μg/kg125I-NGF生物利用度为52.7%。静脉注射125I-NGF 10μg/kg,分布相半衰期为0.13h,消除相半衰期为3.68h,表观分布容积为0.697L/kg,曲线所围面积为16.01μg/h/L。125I-NGF在所测的14种组织中均有分布,其中肾、胃、肠中放射性浓度最高,脑和脊髓最少。肌肉注射125I-NGF主要随尿液排出体外。     

INHIBITIVE KINETIC SPECTROPHOTOMETRIC DETERMINATION OF PROTEIN

A novel inhibitive kinetic spectrophotometric method for the determination of protein is proposed based on the principle that serum albumin (SA) has an inhibitive effect on the oxidation discoloring of p-acetylchlorophosphonazo (CPApA) by potassium periodate in the medium of 4.0 × 10^?4 mol/L H₂SO₄ at 100°C. The maximum absorption peak of SA – CPApA – KIO₄ system is located at 550 nm. The absorbance difference (ΔA) is linearly related with the concentration of SA over the range of 0.80–7.50 µg/mL at the wavelength and fitted the equation: ΔA = 0.064C (C: µg/mL) – 0.0173, with a correlation coefficient γ = 0.9973. The detection limit of the method was 0.30 μg/mL. The method was successfully used to determine protein content in milk and milk powder samples and the determined results were in good agreement with those of tribromoarsenazo spectrophotometry. The relative standard deviation for 13 replicate determinations of the method was 3.64–3.76%. The standard addition recovery of the method was 99.50–101.6%.     

ANALYSIS OF CAPSAICIN AND DIHYDROCAPSAICIN IN HOT PEPPERS BY ULTRASOUND ASSISTED EXTRACTION FOLLOWED BY GAS CHROMATOGRAPHY–MASS SPECTROMETRY

A simple method for the analysis of capsaicin and dihydrocapsaicin in peppers by ultrasound assisted extraction (USAE) followed by gas chromatography–mass spectrometry (GC-MS) has been developed. USAE conditions were optimized by experimental design in order to maximize analyte extraction. A full factorial design involving extraction variables such as solvent (ethanol and water), extraction time (5–25 min), extraction temperature (25–50 °C), sample amount (0.25–0.5 g), and ultrasound amplitude (40–80%) was applied. The most significant conditions for capsaicinoid extraction by USAE were solvent type, extraction time, and sample amount. The obtained results were compared with other extraction methods: the official Soxhlet method and a previously reported solid phase microextraction method. Results showed that the extraction efficiency with the application of USAE (98%) was as good as that obtained with Soxhlet and the precision of recovery was less than 5%; in addition, the extraction time was decreased from 5 h to 25 min. The GC-MS analytical method was linear in the range 10–100 μg/mL for capsaicin and dihydrocpsaicin with correlation coefficient r = 0.998 and peak area variability of ～1% for both capsaicinoids. The method was applied to the analysis of 11 varieties of hot peppers cultivated in México. A large concentration range for capsaicin (101–6800 μg/g) and dihydrocapsaicin (110–2736 μg/g) was found in these pepper samples.     

催化动力学光度法测定痕量普卢利沙星

经研究发现,在缓冲溶液NaOH-KH2PO4介质中,普卢利沙星对H2O2氧化罗丹明B褪色反应有明显的抑制作用,同时又研究该阻抑催化褪色反应的动力学条件,包括酸度、试剂的用量、温度、时间对反应的影响,以及共存离子的干扰,从而建立一种新的快速测定痕量普卢利沙星的阻抑动力学光度法。测定的线性范围为2.0～30μg/mL检出限为0.5μg/mL,回归方程为A=0.0078C+0.064。相关系数r=0996。该方法简便灵敏,准确,选择性好,用于药物中普卢利沙星的测定,获得满意的效果。     

硫酸-H2O2-罗丹明B-体系阻抑动力学光度法测定痕量EDTA的研究

研究阻抑动力学光度法测定痕量EDTA的新体系。在硫酸介质中,Fe（Ⅲ）催化H2O2氧化罗丹明B的反应可被微量EDTA有效地阻抑,被过量EDTA有效的终止,据此建立了测定痕量EDTA的动力学光度法,用固定时间法在555 nm波长处监测阻抑反应。在0～45.0μg/50mL范围为,线性关系良好,回归方程为ΔA=2.25×10^-2c（c：μg/50mL）,γ=0.9991,检出限为1.1×1 0^-6mg/mL。该方法用于罐头等食品中EDTA的测定,获得满意结果。     

Novel determination of caffeine in human urine by direct analysis in real time mass spectrometry

Determination of caffeine is necessary for clinical research. A new method for the determination of caffeine in human urine was established by direct analysis in real time mass spectrometry using multiple reaction monitoring. The m/z 195.1 to 138.1 amu transition was employed in positive ionization mode. The preparation and analysis conditions were systemically optimized. The calibration curve was linear from 0.5–50 µg/mL with a limit of detection limit of 0.2 µg/mL. Intra-day and inter-day accuracy and precision were within the acceptable limits of ±15% at all concentrations. Moreover, the matrix effects for the determination of caffeine were evaluated. In conclusion, a simple, rapid, and reliable method without complex sample preparation and chromatographic separation was developed and validated for the determination of caffeine in human urine.     

二苯偶氮羰酰肼分光光度法测定微量铜

研究Cu~(2+)-DPCO-CTMAB显色反应条件,建立测定微量铜的新方法。络合物的最大吸收波长位于450nm,摩尔吸光系数为3.64×10~4L/mol/cm,在25mL溶液中,铜质量在0～35μg范围内符合比尔定律。以氟化钠、盐酸羟铵和柠檬酸作掩蔽剂消除Fe~(3+)、V~(5+)、Ni~(2+)等干扰。实际样品分析结果的相对标准偏差不大于3.8%,加标回收率为96.6%～104.4%。     

基体匹配——火焰原子吸收法测定钴酸锂中杂质元素

本文采用标准系列钴酸锂基体匹配,用1＋1盐酸溶解,在1％的盐酸介质中,用火焰原子吸收法,测定了钴酸锂中钾、钠、钙、镁、铜、铅、锌、铁、锰、镍等微量杂质含量。通过试验,确定了溶剂和介质的用量;对释放剂SrCl,的加入量进行了实验,选择了最佳加入量;对溶剂和样品中的共存元素进行了干扰实验。各元素的检出限分别为：钾：0．005μg／mL,钠：0．004μg／mL,钙：0．009μg／mL,镁：0．005μg／mL,铜：0．005μg／mL,铅：0．019μg／mL,锌：0．009μg／mL,铁：0．0151μg／mL,锰：0．005μg／mL,镍：0．012μg／mL,样品加标回收率在98—104％之间,相对标准偏差（RSD）为：0．96-9％,方法简便、快捷,仪器低廉,易于普及,适于钴酸锂中的微量元素检测。     

两次双波长分光光度法同时测定痕量铝(Ⅲ)和铁(Ⅲ)

研究以MTB为显色剂、CTMAB为增溶增敏剂 ,利用系数补偿和双峰双波长的两次双波长分光光度法 ,同时测定A1(Ⅲ )和Fe (Ⅲ )的实验条件 ,线性范围A1:0～ 2 5 μg/ 2 5mL、Fe :0～ 30 μg/ 2 5mL ,该法用于合成水样和硅石试样的测定 ,结果满意     

Kinetic Spectrophotometric Determination of Traces of Iron by its Catalytic Effect on the Oxidation of m-Acetylchlorophosphonazo by Hydrogen Peroxide

Abstract

In the buffer medium of KHC₈H₄O₄–HCl at pH 3.2, a catalytic kinetic spectrophotometric method for the determination of iron was developed by use of the catalytic effect of iron(III) on the oxidation of m-acetylchlorophosphonazo by hydrogen peroxide. At the wavelength of 544 nm, the difference of absorbance(?A) is well linearly related with the concentration of iron(III) in the range of 0–2.5 µg/25 mL and fitted the equation: ?A = 0.1469 C(µg/25 mL) + 0.0037, with a regression coefficient of 0.9979.The detection limit of the method is 1.34 ng/mL. The present method was successfully applied to determine iron in rice samples.     

CATALYTIC KINETIC SPECTROPHOTOMETRIC DETERMINATION OF TRACE AMOUNTS OF ETHYLENEDIAMINETETRAACETIC ACID BASED ON ITS CATALYTIC EFFECT ON THE REACTION OF RHODAMINE B AND POTASSIUM DICHROMATE

A new method for the determination of trace ethylenediaminetetraacetic acid (EDTA) was developed using catalytic kinetic spectrophotometry based on the principle that in the medium of 0.10 mol/L sulfuric acid, trace EDTA has a catalytic effect on the oxidation of rhodamine B by potassium dichromate, and a suitable amount of 6.0 mol/L NaOH solution can inhibit the catalytic reaction. At the maximum absorption wavelength of 546 nm, the linear range for the determination of EDTA was shown over the concentration range 5.0 × 10^?5–7.0 × 10^?4 mol/L and the detection limit of this method for EDTA was 0.0501 mmol/L. The linear regression equation for the determination of EDTA and regression coefficient were ΔA = 512C (C: mol/L) + 0.0966, γ = 0.9993, respectively. The apparent activation energy of the catalytic reaction was 81.57 KJ/mol. The proposed method has been successfully applied to the determination of trace ethylenediaminetetraacetic acid in water and apple tinned foodstuff samples with satisfactory results. The relative standard deviation of 13 replicate determinations of EDTA was 1.15–2.37% and the recovery of the method was 99.90–102.7%, respectively. The determined results were in good agreement with that of established method Fe(III)-H₂O₂-bromothymol blue system inhibitory-kinetic spectrophotometry.     

DETERMINATION OF TRACE CADMIUM BY FLOW INJECTION ON-LINE MICROCOLUMN PRECONCENTRATION COUPLED WITH FLAME ATOMIC ABSORPTION SPECTROMETRY USING HUMAN HAIR AS A SORBENT

A novel method using a cone-shaped pipette tip packed with human hair as an adsorption material has been developed for the on-line flow injection preconcentration of trace Cd(II) ions based on its complex formation with the ammonium pyrrolidine dithiocarbamate (APDC) prior to flame atomic absorption spectrometric (FAAS) determination. Cd-PDC complex sorbed on the human hair was eluted by 4.0 mol L^?1 HNO₃. The enhancement factor is 19, and the detection limit (3σ) is 0.77 μg L^?1. The proposed method was successfully applied to the determination of trace cadmium in drinking water, beverage samples, and the certified reference materials.     

DETERMINATION OF CATECHINS IN TEA BY MICELLAR ELECTROKINETIC CHROMATOGRAPHY WITH A GRAPHENE OXIDE-COATED CAPILLARY

A novel approach was developed for the determination of four catechins, (-)-epigallocatechin gallate, (-)-epigallocatechin, (-)-gallocatechin gallate, and (-)-epicatechin, in tea by micellar electrokinetic chromatography (MEKC) using an acidic phosphate buffer (40 mM, 100 mM sodium dodecyl sulfate, and 30% methanol, pH 3.0). The linear dynamic ranges for the catechins were between 25 and 250 μg/mL, and the graphene oxide-coated capillary offered satisfactory accuracy, precision, and limits of detection. The developed method was employed for the determination of catechins in tea.     

A GREEN METHOD FOR THE DETERMINATION OF CHROMIUM(VI) AND IRON(III) IN WATER BY SEQUENTIAL INJECTION ANALYSIS AND SPECTROPHOTOMETRIC DETECTION

In this article, an organic-reagent-free method was described for the determination of Cr(VI) and Fe(III) by double-system double-wavelength sequential injection technique with a single sample injection. In this approach, the determination of Cr(VI) was based on the detection of a blue unstable intermediate compound resulting from the reaction of Cr(VI) with hydrogen peroxide, and the determination of Fe(III) was based on the color reaction of Fe(III) with thiocyanate in acidic medium. Sequential injection analysis (SIA) parameters, including spacer solution volume, aspiration order, aspiration volumes, flow rate, acid medium, solution acidity, and reagent concentrations, were optimized. The linear range for the determination was 3.0–60.0 μg mL^?1 for Cr(VI) and 1.0–40.0 μg mL^?1 for Fe(III), respectively. The limit of detection (LOD) was 0.6 μg mL^?1 for Cr(VI) and 0.2 μg mL^?1 for Fe(III), and the limit of quantitation (LOQ) was 2.0 μg mL^?1 for Cr(VI) and 0.67 μg mL^?1 for Fe(III). The total volume of the reagent consumed in each determination was only 0.11 mL. The proposed method was applied to the simultaneous determination of Cr(VI) and Fe(III) in electroplating wastewater and environmental waters. The results were in good agreement with those obtained by atomic absorption spectrometry. The recoveries were in the range of 97.5–101.1%.     

HPLC法测定2,3-二氢苯并呋喃-5-甲醛的含量及其有关物质

建立HPLC法测定2,3-二氢苯并呋喃-5-甲醛的含量及其有关物质。采用Dia-monsilC_(18)柱,以甲醇一水(48:52)为流动相,检测波长为300nm(主成分含量测定)与278 nm(有关物质测定),流速:1.2mL/min。在此条件下,主峰与杂质分离良好,2,3-二氢苯并呋喃-5-甲醛和2,3-二氢苯并呋喃分别在20～160 μ g/mL,100～800 μg/mL浓度范围内呈良好的线性关系,此方法简便可靠,专属性好,灵敏度高。     

DETERMINATION AND SEPARATION MECHANISM OF ACRYLAMIDE BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

High-performance liquid chromatography using the negative peak method was developed for the determination and separation of acrylamide in food with methanol-water containing a background reagent of 0.01 mmol L^?1 5-sulfosalicylic acid (15/85, v/v) as the mobile phase with an ultraviolet-visible detector (λ_sig = 320 nm, λ_ref = 210 nm). The method was simple, the correlation coefficients exceeded 0.9990, and the limit of detection for acrylamide was 0.07 μg kg^?1. The concentrations of acrylamide in food were between 81 and 910 μg kg^?1. The recoveries were greater than 81.0% and the relative standard deviation was between 0.24 and 3.6%. The results showed that this method was suitable for the determination of acrylamide in food.     

新苯并噻唑偶氮类显色剂BTAR光度法测定微量铁

研究了新显色剂5-（6-溴苯并噻唑-2-偶氮）-2,6-二羟基苯甲酸（BTAB）与铁的显色反应及高纯石英砂中微量铁的测定。在pH=6．2的醋酸盐缓冲体系和溴代十六烷基吡啶溶液（CPB）存在下,BTAB与Fe（11）形成1：2的红色配合物,在566．0nm处有最大吸收,稳定常数为5．10×10^9,摩尔吸光系数为1．185×10^4L／（mol·cm）,铁含量在0～2．54μg／mL内符合朗伯-比耳定律,建立了一种新的Fe（II）的测定方法。反应有很好的选择性。不经分离、掩蔽可直接测定高纯石英砂中微量铁。     

DETERMINATION OF CINACALCET HYDROCHLORIDE BY CAPILLARY ELECTROPHORESIS WITH PHOTODIODE ARRAY DETECTION

This article reports a validated stability-indicating capillary electrophoresis method using a photodiode array detector at 220 nm for the determination of cinacalcet hydrochloride. The best electrophoretic separation between the analyte and internal standard (lamotrigine) was achieved within 5 min in a deactivated fused silica capillary (55 cm effective length × 75 µm internal diameter) maintained at 24°C using a background electrolyte solution consisted of phosphate buffer (50 mM, pH 6.4):methanol (95:5, v/v) at a separation voltage of 30 kV. The linear range of the method was 0.5–30 µg/mL (r = 0.9999) with limits of detection and quantitation of 0.1 and 0.5 µg/mL, respectively. The assay precision and accuracy were favorable as the relative standard deviations did not exceed 1.09%, and the recovery values were 98.99–100.33 ± 0.19–1.09%. The induced degradation products, when any, did not interfere with the detection of analyte. The proposed method was successfully applied for the determination of cinacalcet hydrochloride in bulk and pharmaceutical formulations; the percentage recovery values were 98.16–102.00 ± 0.24–1.08%. The results demonstrated the value of the method.     

Flow‐Injection Chemiluminescence Determination of Catecholamines

Abstract

A new flow‐injection chemiluminescence method is proposed for the determination of catecholamines, including adrenaline, dopamine, and l‐Dopa. The method is based on the chemiluminescence (CL) produced during the oxidation of catecholamines by sodium hypochlorite in an alkaline medium. The CL intensity is greatly increased when 2,7‐dichlorofluoresceine is used as a sensitizer. The calibration graphs are linear in the range of 3–80 µg/mL for adrenaline and l‐Dopa and 3–50 µg/mL for dopamine. The influence of foreign compounds was studied and the method was applied to the determination of catecholamines in pharmaceutical formulations.