以meso-四(N-甲基-3-吡啶基)卟啉荧光光度测定痕量锌的研究

研究了以meso-四(N-甲基-3-吡啶基)卟啉测定锌痕量锌的荧光光度法, 其灵敏度较其它水溶性卟啉衍生物测定锌的分光光度法要高, 检出量为1ppb, 线性范围为0-1.0μg/25mL. 方法已用于测定自来水和头发中的微量锌, 结果满意.     

Two different strategies for the fluorimetric determination of piroxicam in serum

Two different spectrofluorimetric methods for the determination of piroxicam (PX) in serum are presented and discussed. One of them is based on the use of three-way fluorescence data and multivariate calibration performed with parallel factor analysis (PARAFAC) and self-weighted alternating trilinear decomposition (SWATLD). This methodology exploits the so-called second-order advantage of the three-way data, allowing to obtain the concentration of the studied analyte in the presence of any number of uncalibrated (serum) components. The method was developed following two different procedures: internal standard addition and external calibration with standard solutions, which were compared and discussed. The second approach investigated is based on the combination of solid-phase extraction (SPE) and room temperature fluorimetry. Both methods here presented yield satisfactory results. The concentration range in which PX could be determined in serum was 1–10 μg ml⁻¹. The limits of quantification for the experimental solutions using the chemometric approach were 0.09 μg ml⁻¹ for the standard addition mode and 0.12 μg ml⁻¹ using external calibration (both for PARAFAC and SWATLD algorithms). In the solid-surface fluorimetric method, the calibration graph was linear up to 0.22 μg ml⁻¹ and the limit of quantification was 0.02 μg ml⁻¹.     

Development of a novel flow injection liquid-liquid microextraction method for the on-line separation and preconcentration for determination of zinc(II) using 5-(8-hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane as a sensitive and selective fluorescent chemosensor

A novel flow injection analysis (FIA) system based on liquid-liquid microextraction and fluorimetric determination was developed for the determination of traces of the Zn²⁺ ion using 5-(8-hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane (L) as a sensitive and selective fluorimetric sensor, with λ_ex = 373 nm and λ_em = 530 nm, and hexanol as the extracting organic solvent. In the designed FIA system, the phase separation takes place via gravitation forces in the absence of any segmenter. The influence of pH and ionic strength of the solution, amount of ligand, nature of counter ion, volume of organic solvent, extraction time and coil length was investigated. Under optimized experimental conditions, the calibration curve found to be liner over a concentration range of 0.025-4.53 μg mL⁻¹ (R² = 0.9951) with a limit of detection of 2.3 ng mL⁻¹. The enrichment factor was 45 and relative standard deviation for 7 replicate determinations was 2.43%. The method is very fast and uses low levels of organic solvents. The proposed method was applied successfully to the determination of zinc(II) in human hair, human serum and two inorganic sludge samples.     

A continuous flow system combined with a sensing fluorimetric transductor for the determination of β-naphthol

A single automatic method for continuous flow determination of β-naphthol based on the enhancement of its native fluorescence once the analyte was transitorily retained on-line on a solid support (QAE A-25 resin) is reported. So, a flow-through optosensor was developed using a flow-injection analysis system with solid phase fluorimetric transduction. KCl (0.15 mol l⁻¹) at pH 12.0 was used as carrier solution. To obtain the optimum fluorescence signal the wavelengths chosen were 245 nm (excitation) and 420 nm (emission). The response of the sensor was directly proportional to the sample volume injected in the studied range 40-1500 μl. Approximately one higher order of magnitude is achieved in sensitivity when 1500 μl are used with respect to the use of 40 μl of sample. The sensor was calibrated for three different injection volumes: 40, 600 and 1500 μl, responding linearly in the measuring range of 2-60, 0.5-15 and 0.2-5 μg l⁻¹ with detection limits of 0.5, 0.09 and 0.05 μg l⁻¹, respectively. The relative standard deviation for ten independent determination is 0.6% (40 μl), 0.9% (600 μl) and 2.3% (1500 μl). A recovery study was performed onto three different spiked water samples at concentration levels from 1 to 2.5 μg l⁻¹ and the recovery percentage from the experimental data ranged between 101±2 and 105±5.     

阻抑荧光动力学法测定痕量司帕沙星

研究了Tris水溶液中司帕沙星对Cu（Ⅱ）催化H2O2氧化罗丹明B荧光猝灭体系的抑制作用,发现司帕沙星的质量浓度在0.098～1.372 ng/mL范围内与该体系的荧光强度成良好的线性关系,据此,建立了动力学荧光测定痕量司帕沙星的新方法.该方法检出限可达0.058 ng/mL,并用于制剂及体液中司帕沙星的分析,回收率为98.3%～102.1%.     

Ultraviolet irradiation and polarographic adsorptive complex wave techniques for the simple and rapid simultaneous determination of trace amounts of zinc,lead and copper in human hair

Polarographic adsorptive complex waves in the presence of catechol violet were studied for the simple and rapid simultaneous determination of traces of zinc, lead and copper in human hair and UV irradiation techniques were compared with conventional acid digestion procedures. UV irradiation of acidified hair with a 500-W mercury are lamp releases bound zinc, lead and copper after 3 h. Compared with the acid digestion procedure, the blank of the UV irradiation method is lower, the amounts of reagents used are smaller and the sample manipulations are simpler. The mechanisms of the polarographic adsorptive complex waves of Zn-, Pb-Cu- catechol violet are discussed.     

原子捕集-导数火焰原子吸收光谱法测定中草药中的微量锌

提出了原子捕集－导数火焰原子吸收光谱法，考察了捕集管位置，火焰状态、冷却水流量、捕集时间、导数测量系统灵敏度档等实验条件对灵敏度的影响。在测量系统20mV/min灵敏度档下，捕集5min，特征浓度为0．037ng/mL，较常规火焰原子吸收光谱法提高了1243倍。     

200 years of practical electroanalytical chemistry: past, present and future directions illustrated by reference to the on-line, on-stream and off-line determination of trace metals in zinc plant electrolyte by voltammetric and potentiometric techniques

The millennium being celebrated this year coincides with the 200th anniversary of the birth of practical electrochemistry made possible via Volta’s publication of the battery in the year 1800. The analytical chemists at the beginning of the 19th century were very quick to take advantage of this newly reported device and the first qualitative electrochemical determination of copper rapidly followed this pioneering discovery. In the last 200 years, electrochemical analysis, in its various forms, has been undertaken routinely in countless laboratories all over the world. However, in view of the long and distinguished history of the discipline, and some limitations that have been identified at the time of the celebration of the millennium, electrochemical analysis is regarded in some quarters as being a mature and conservative discipline whose importance in the future, when faced with severe competition from newly emerging alternative analytical techniques, is somewhat unclear. In this paper, an overview of past and present developments in electroanalytical chemistry and the possible future status of the technique is presented. In particular, emphasis is given to describing applications relevant to the also very mature field of electrowinning of zinc from plant electrolyte. This overview encompasses the author’s 25 years’ experience in developing polarographic, stripping voltammetric, adsorptive stripping voltammetric and ion-selective electrode (ISE) methods of analysis in on-line, on-stream and off-line modes for the determination of elements such as Cd, Pb, Ge, Sb (oxidation states (III) and (V)), Co, Ni, Zn, Fe, (oxidation states (II) and (III)), Tl, As (total) and Cu in zinc plant electrolyte. Developments that may contribute to an important future for analytical voltammetry are also considered as are limitations that could inhibit the extent of practical use of these electroanalytical techniques in the 21st century.     

Extractive spectrophotometric determination of niobium(V) using 3-hydroxyflavone

A simple, rapid method for the spectrophotometric determination of niobium in trace amounts is presented, employing 3-hydroxyflavone as a ligand for the complexation of the metal ion and extracting the coloured complex into chloroform from 4M HClO₄ solution. Beer's law is obeyed in the range 0.0 to 3.2 g ml^–1 Nb(V), with a lower working limit of 0.1 g ml^–1 Nb(V). Molar absorptivity and Sandell's sensitivity of the complex at 395 nm are 4.088 × 10⁴l mol^–1 cm^–1 and 0.002g Nb(V) cm^–2, respectively. The stoichiometry of the complex is established as 12 by Job's and mole ratio methods. The method is free from the interference of a large number of analytically important elements. The proposed system handles satisfactorily the analysis of several samples of varying complexity. The results are highly reproducible with a relative standard deviation of 0.34% for 20 g of Nb.     

Development of a novel multi-element detection system for trace metal determination based on chemiluminescence after separation by ion chromatography

A highly sensitive, non-selective trace metal detector based on chemiluminescence has been developed. The metals, separated by simple ion-exchange chromatography, bring about the displacement of cobalt from a Co-EDTA post-column reagent. The liberated cobalt is then detected by the luminol-peroxide chemiluminescence reaction using a modified spectrofluorimeter as the detector. The metals determined are Mg, Ca, Sr, Ba, Fe(II), Fe(III), Co, Ni, Cu, Zn, the lanthanides, Th, Al, Ga, In, Pb and Bi. The detection limits (three times the baseline noise) range between 2 and 100 μg l^?1, depending on the analyte, for a 200-μl injection. To demonstrate the quantitative performance of the detector, the zinc and aluminium contents of a fresh water certified reference material was determined and gave good agreement with the certificate values.     

High sensitive determination of zinc with novel water-soluble small molecular fluorescent sensor

A high sensitive method of quantitative analysis for the determination of zinc in the nutrition supplements has been developed by using a novel water-soluble fluorescent sensor HQ3: (8-pyridylmethyloxy-2-methyl-quinoline). Under the optimized condition of 67 mM phosphate buffer, pH 7.4, and 5% (v/v) DMSO, the zinc concentration showed good linear relationship with fluorescence intensity in the range of 7.5 × 10⁻⁸ to 2.5 × 10⁻⁵ M with the detection limit of 1.5 × 10⁻⁸ M. HQ3 exhibited high selectivity to zinc comparing with other metal ions except for cadmium. The developed analytical method was successfully used for determining the content of zinc in a real sample of zinc gluconate solution of Sanchine.     

锌-硫氰酸盐-结晶紫体系共振散射法测定痕量锌

在pH 5.0 NaAc-HAc介质和吐温80溶液中,研究了zn(SCN)42-与结晶紫形成的离子缔合微粒的共振散射光谱,考察了其各种影响因素和适宜的反应条件,确定了共振散射强度与Zn2+浓度的关系,建立了测定痕量zn(Ⅱ)的共振散射新方法.研究表明,在0.020～0.80μg/mL范围内,体系的共振散射强度△I与Zn...     

Application of the Total Reflection X-ray Fluorescence technique to trace elements determination in tobacco

Many studies have identified an important number of toxic elements along with organic carcinogen molecules and radioactive isotopes in tobacco. In this work we have analyzed by Total Reflection X-Ray Fluorescence 9 brands of cigarettes being manufactured and distributed in the Mexican market. Two National Institute of Standards and Technology standards and a blank were equally treated at the same time. Results show the presence of some toxic elements such as Pb and Ni. These results are compared with available data for some foreign brands, while their implications for health are discussed. It can be confirmed that the Total Reflection X-Ray Fluorescence method provides precise (reproducible) and accuracy (trueness) data for 15 elements concentration in tobacco samples.     

顺序注射停流分光光度法测定痕量碘

食物中碘的含量一直是人们关注的问题,研究食物中微量碘的分析方法具有重要的现实意义.目前测定碘的方法主要有色谱法[1,2]、荧光法[3,4]、分光光度法[5,6]等.     

Spectrofluorimetric determination of human serum albumin using a doxycycline-europium probe

A new spectrofluorimetric method is proposed for determination of human serum albumin (HSA) with the limit of detection at ng levels. Using doxycycline (DC)-europium (Eu³⁺) as a fluorescent probe, in a buffer solution of pH 10.2, HSA can remarkably enhance the fluorescence intensity of the DC-Eu³⁺ complex at 612 nm and the enhanced fluorescence intensity of Eu³⁺ is proportional to the concentration of HSA. Optimum conditions for the determination of HSA are also investigated. The linear ranges for HSA are 0-9.2 and 9.2-34.5 μg ml⁻¹ with limits of detection of 64 and 115 ng ml⁻¹, respectively. This method is simple, practical and relatively free of interference from coexisting substances, as well as much more sensitive than most of the existing assays. The determination results for human serum and urine samples are identical to those by the AOAO method, with relative standard deviations of five determinations of 1.1-3.6%. By the Rosenthal graphic method, the binding number and association constant of human serum albumin with the probe are 1.8 and 3.71×10⁵ l mol⁻¹, respectively.     

Candoluminescence-a new flame technique for trace analysis-I Development of a method for determination of bismuth

Early work on candoluminescence is reviewed and the phenomenon is investigated experimentally for the elements Bi, Mn, Sb and the lanthanides. It is demonstrated that it is feasible to determine bismuth (5-1000mug) by measuring its candoluminescent intensity at 399 nm, using a calcium hydroxide-calcium sulphate matrix and a hydrogen-helium-air flame.     

Synthesis and characterization of a novel cross-linking complex of beta-cyclodextrin-o-vanillin furfuralhydrazone and highly selective spectrofluorimetric determination of trace gallium

A novel host inclusion complex of cross-linking-polymeric-β-cyclodextrin-o-vanillin furfuralhydrazone (β-CDP-OVFH) was synthesized and characterized with IR and ¹H NMR spectra to confirm its structure. A highly selective and sensitive fluorescent determination of trace amounts of gallium was proposed based on the reaction between Ga³⁺ with β-CDP-OVFH in acetic acid-ammonium acetate buffer medium of pH 4.10. The maximum excitation and emission wavelengths were 392 and 499 nm, respectively. The linear range of this method was 1.5-330 ng ml⁻¹ with a detection limit of 0.44 ng ml⁻¹. The effect of interferences in the determination of gallium was investigated and the results showed that the same race elements such as Al³⁺ and In³⁺ did not interfere the determination of Ga³⁺ even when their concentration is 100 times of Ga³⁺, the host reagent had quite high capacity of identifying Ga³⁺. This method was successfully applied to the determination of trace amounts of Ga³⁺ in artificial and semiconductor samples.     

Titrimetric determination of trace sulfur in petroleum using a lead ion selective electrode

Summary A method for the determination of trace total sulfur in petroleum distillates is described. The petroleum sample is combusted using an oxyhydrogen burner. The combustion products are collected in 50 ml of absorber solution containing 10 mg of sodium nitrite and 0.444 mg of sodium sulfate. The excess nitrite is destroyed by boiling. After cooling, sufficient 1,4-dioxane is added to make a 50 volume % solution for the titration. The titration is carried out using –0.5amp polarizing current through a lead ion-selective electrode. Standardized (0.0025M) lead perchlorate is the titrant. The potential break at the endpoint is determined graphically from the titration curve and related to the total sulfur in the petroleum sample.

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Zusammenfassung Ein Verfahren zur Bestimmung von Spuren Gesamtschwefel in Erdöldestillaten wurde beschrieben. Die Probe wird in einer Knallgasflamme verbrannt, die Verbrennungsprodukte werden in 50 ml einer Absorptionslösung aufgefangen, die 10 mg Natriumnitrit und 0,444 mg Natriumsulfat enthält. Das überschüssige Nitrit wird durch Kochen zerstört. Nach dem Abkühlen setzt man der Flüssigkeit das gleiche Volumen Dioxan zu und titriert unter Verwendung einer für Bleiionen spezifischen Elektrode mit einem Polarisationsstrom von –0,5Amp. 0,0025-m Bleiperchlorat dient als Maßlösung. Der Potentialsprung beim Endpunkt wird graphisch ermittelt und entspricht dem Gesamtschwefelgehalt der Probe.

     

Evaluation of a spectrofluorimetric method for the selective determination of thalidomide in pharmaceutical tablets, urine and blood serum

A spectrofluorimetric analytical methodology for the determination of thalidomide in pharmaceutical formulations, blood serum and urine was developed and evaluated in terms of sensibility and selectivity. Efforts were spent on the maximization of thalidomide fluorescence signal and on the increasing of selectivity when analyzing complex samples, specially, in samples containing sulfanilamide, a strongly fluorescent concomitant that can be used in association with thalidomide. Maximum signal was observed with optimized composition of the solvent system and pH. Approaches to enable selective determination of thalidomide in the presence of sulfanilamide were tested and compared. Better results were achieved using the combined use of acidic medium and UV treatment. For urine and blood serum samples, a solid phase extraction (on a C₁₈ cartridge) was found to be practical, enabling good recovery results. Limit of detection (3S_b/m) was estimated to be 1.2 μg l⁻¹, approximately 100 times better than the ones reported for the routine UV absorption HPLC methods. This low-cost spectrofluorimetric methodology was found to be very simple and enabled excellent recoveries when analyzing analyte spiked biological fluids as well as thalidomide based commercial and laboratory made pharmaceutical formulations.