酸性铬兰K分光光度法测定血红蛋白

在pH 3.2的Clark-Lub’s缓冲溶液中,酸性铬兰K与血红蛋白发生反应,使体系吸光度增大,在375 nm处的吸光度增加值与血红蛋白的加入量成正比,据此建立了测定血红蛋白的分光光度法。探讨了测定血红蛋白的最佳条件和干扰情况,方法的线性范围0～112μg/mL,表观摩尔吸光系数ε375为4.7×105L.mol-.1cm-1,方法已用于动物血液和人尿液中血红蛋白含量的测定。     

The effects of copper ions on the catalytical degradation of azo dye acid chrome blue K

The effects of Cu²⁺ on the catalytical degradation of acid chrome blue K (ACBK) in UV-TiO₂ and H₂O₂ processes were studied. In these two processes, Cu²⁺ markedly depressed the catalytical degradation of ACBK by its interaction with ACBK. Through this interaction, the new complex Cu(ACBK)₂ formed. The formation of this new complex was favorable to protect some groups in ACBK from the oxidation of reactive oxygen generated in UV-TiO₂ and H₂O₂ processes, and consequently had suppressing effects on degradation of ACBK. In addition, Cu²⁺ also inhibited the degradation of ACBK in UV-TiO₂ process by influencing the adsorption of ACBK on the surface of TiO₂ particles.      

Simultaneous Determination of Cobalt and Nickel in Wastewater with 2‐Hydroxyl‐5‐benzeneazoformoamithiozone by Spectral Correction Technique

A new chromogenic reagent, 2-hydroxyl-5-benzeneazoformoamithiozone (HBASA) was synthesized and it can complex Co(II) and Ni(II) at pH 6.0 with high sensitivity and good selectivity. The complexations were characterized by a spectral correction technique. Complexes Co(HBASA)₂ and Ni(HBASA) were formed and their stepwise stability constants (K_n) and stepwise molar absorptivities (ϵ_n) were worked out. The spectral correction matrix method was applied to the simultaneous determination of Co and Ni. At the range from 0 to 12.0 μg/25-mL Co and Ni, the correction absorbances (Aβ) of the mixed complexes' solutions have good linearity. The limit of detection is 0.01 mg/l Co and 0.03 mg/l Ni and the relative standard deviation (RSD) is 2.5% for Co and 5.6% for Ni. This method was applied to the analysis of wastewater. The recovery of Co was between 94.5 and 109% and that of Ni between 99.0 and 111%.     

Electrochemical determination of heparin using methylene blue probe and study on competition of Ba with methylene blue for binding heparin

Cyclic voltammetric investigation of the interaction of methylene blue (MB) with heparin (hep) at a gold electrode is presented. The combination of MB with heparin formed a nonelectroactive complex MB-hep, which resulted in the peak current decrease of MB. The anodic peak current difference of MB was found to be proportional to the concentration of heparin in the range of 0.666-64.5 μg mL⁻¹ with a detection limit of 270 ng mL⁻¹ and a satisfactory result was obtained for the determination of heparin in injection samples. The equilibrium constant for MB-hep complex was calculated to be 7.32 × 10⁵. The dynamic process of competition of Ba²⁺ with methylene blue for binding heparin was monitored using quartz crystal microbalance (QCM) technique. The reaction rate constant between Ba²⁺ and MB-hep was estimated to be 0.0022 s⁻¹.     

A simple and sensitive resonance scattering spectral method for determination of hydroxyl radical in Fenton system using rhodamine S and its application to screening the antioxidant

Based on resonance scattering (RS) effect of rhodamine dye association particles, a new resonance scattering method for the determination of hydroxyl free radical from Fenton reaction was developed. In HCl-NaAc buffer solution, the OH of Fenton reaction oxidized the excess I⁻ to I₃⁻. The I₃⁻ combined, respectively, with rhodamine B (RhB), butyl rhodamine B (b-RhB), rhodamine 6G (RhG) and rhodamine S (RhS) to form association particles that exhibit stronger resonance scattering effect at 420 nm and 610 nm. However, the RS peak at about 610 nm was interfered with its synchronous fluorescence peak at 580 nm for RhB, 580 nm for b-RhB, 560 nm for RhG and 560 nm for RhS, respectively. The concentration of H₂O₂ in the range of 0.648-21.6 μmol/L, 0.423-13.0 μmol/L, 0.216-13.0 μmol/L and 0.092-13.0 μmol/L was linear to its resonance scattering intensity at 420 nm. Its detection limit was 0.15 μmol/L, 0.10 μmol/L, 0.092 μmol/L and 0.044 μmol/L, H₂O₂, respectively. This RhS RS method was applied to selection of the antioxidant, with satisfactory results.     

Studies on the mixed-ligand complexes of copper(II) with gallic acid and pyridine carboxylic acids and their benzologues

Summary The ternary complex formation of copper(II) with gallic acid (gal) and 2-hydroxy nicotinic acid (hyna), 2-mercapto nicotinic acid (mena), salicylic acid (sa) or thiosalicylic acid (tsa) as a second ligand in a 1:1:1 molar ratio has been investigated in 40% (v/v) ethanol using spectrophotometric andpH titration methods. The solution equilibria of the ternary systems have been determined and the stability constants of the mixed complexes has been evaluated. Considering all parameters, the Cu-gal-sa ternary system was proved as a suitable, rapid, and sensitive spectrophotometric indicator for determining traces of copper.The ternary system containingsa obeysBeer's law up to 3.4 µg·ml^–1 copper. The optimum range for the determination of copper (Ringbom) atpH 6.0 ranges from 0.63 to 1.74 µg·ml^–1 of copper. The molar absorptivity of the ternary complex is 1.3×10⁴l·mol^–1·cm^–1.

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Untersuchungen anmixed-ligand — Komplexen von Kupfer(II) mit 3,4,5-Trihydroxybenzoesäure und Pyridincarbonsäuren und ihren C-Homologen

Zusammenfassung Die Bildung ternärer Komplexe von Kupfer(II) mit 3,4,5-Trihydroxybenzoesäure (gal) und 2-Hydroxynicotinsäure (hyna), 2-Mercaptonicotinsäure (mena), Salicylsäure (sa) oder Thiosalicylsäure (tsa) in einem molaren Verhältnis von 1:1:1 wurde mittels spektrophotometrischer und potentiometrischer Methoden in 40% (v/v) Ethanol untersucht. Die Lösungsgleichgewichte der termären Systeme und die Stabilitätskonstanten der gemischten Komplexe wurden bestimmt. Unter Berücksichtigung aller Parameter erwies sich das termäre System Cu-gal-sa als geeigneter schneller und empfindlicher Indikator zur Spurenanalyse von Kupfer.Dassa enthaltende ternäre System gehorcht demBeerschen Gesetz bis zu einer Kupferkonzentration von 3.4 µg·ml^–1. Der optimale Bereich zur Bestimmung von Kupfer (Ringbom) beipH 6.0 erstreckt sich von 0.63 bis 1.74 µg Cu pro ml. Die molare Extinktion des ternären Komplexes beträgt 1.3×10⁴l·mol·cm^–1.

     

Simultaneous determination of alcohols including diols and triols by HPLC with ultraviolet detection based on the formation of a copper(II) complex

We developed a reversed‐phase high‐performance liquid chromatography method with ultraviolet detection using on‐line complexation with Cu(II) ion for analysis of five alcohols including diols and triol (methanol, ethanol, 1,2‐propanediol, 1,3‐propanediol, and glycerol). The Cu(II) ion concentration in the mobile phase had a great influence on the peak areas of these alcohols, but not on their retention times. Column temperature (25−40°C) and pH of the mobile phase did not affect the separation of analytes. The optimum separation conditions were determined as 5 mM CuSO₄, 3 mM H₂SO₄, and 3 mM NaOH at 30°C. The ratio of the peak areas for three alcohols (methanol, 1,2‐propanediol, and glycerol) was in good agreement with that calculated from the obtained stability constants, molar absorption coefficients for the 1:1 Cu(II) complexes with the three alcohols, and the injected molar quantities. This fact strongly suggests that the observed high‐performance liquid chromatography signals resulted from formation of the 1:1 Cu(II)–alcohol complexes. Using the proposed method, these five alcohols in spirit, liquid for electronic cigarette, mouthwash, and nail enamel remover samples were successfully analyzed with only a simple pretreatment.     

A continuous approach for the determination of Cr(VI) in sediment and soil based on the coupling of microwave-assisted water extraction, preconcentration, derivatization and photometric detection

A dynamic system for the continuous leaching of Cr(VI) from sediment and soil based on both microwave assistance and iterative change of the flow direction of the extractant through the sample cell has been developed. The microwave-assisted extractor has been coupled to a photometric detector through a flow injection interface in order to develop a fully automated method. The Cr(VI) extracted was monitored after derivatization with 1,5-diphenylcarbazide. Two approaches are proposed which differ in the inclusion of a preconcentration minicolumn packed with a strong anion exchange resin. A 0.04 M ammonium buffer solution was used as extractant and 0.2 g of sample—river sediment spiked with 50 and 5 μg g⁻¹ for the method without preconcentration (method A) and with preconcentration (method B)—was subjected to 8-14 min of 300 W microwave-assisted extraction. The within-laboratory reproducibility and repeatability were 2.6 and 1.9 for method A, and 4.0 and 2.6 for method B. The proposed methods have been compared with the reference EPA method 3060/7196.     

Ultra-sensitive DNA assay based on single-molecule detection coupled with fluorescent quantum dot-labeling and its application to determination of messenger RNA

Rapid, inexpensive, and convenient methods for quantifying elemental sulfur (S⁰) with low or sub-μg g⁻¹ limits of detection would be useful for a range of applications where S⁰ can act as a precursor for noxious off-aromas, e.g., S⁰ in pesticide residues on winegrapes or as a contaminant in drywall. However, existing quantification methods rely on toxic reagents, expensive and cumbersome equipment, or demonstrate poor selectivity. We have developed and optimized an inexpensive, rapid method (∼15 min per sample) for quantifying S⁰ in complex matrices. Following dispersion of the sample in PEG-400 and buffering, S⁰ is quantitatively reduced to H₂S in situ by dithiothreitol and simultaneously quantified by commercially available colorimetric H₂S detection tubes. By employing multiple tubes, the method demonstrated linearity from 0.03 to 100 μg S⁰ g⁻¹ for a 5 g sample (R² = 0.994, mean CV = 6.4%), and the methodological detection limit was 0.01 μg S⁰ g⁻¹. Interferences from sulfite or sulfate were not observed. Mean recovery of an S⁰ containing sulfur fungicide in grape macerate was 84.7% with a mean CV of 10.4%. Mean recovery of S⁰ in a colloidal sulfur preparation from a drywall matrix was 106.6% with a mean CV of 6.9%. Comparable methodological detection limits, sensitivity, and recoveries were achieved in grape juice, grape macerate and with 1 g drywall samples, indicating that the methodology should be robust across a range of complex matrices.     

A novel method for the determination of trace copper in cereals by dispersive liquid-liquid microextraction based on solidification of floating organic drop coupled with flame atomic absorption spectrometry

A novel,simple,rapid,efficient and environment-friendly method for the determination of trace copper in cereal samples was developed by using dispersive liquid-liquid microextraction based on solidification of floating organic drop(DLLME-SFO) followed by flame atomic absorption spectrometry.In the DLLME-SFO,copper was complexed with 8-hydroxy quinoline and extracted into a small volume of 1-dodecanol,which is of low density,low toxicity and proper melting point near room temperature. The experimental parameters affecting the extraction efficiency were investigated and optimized.Under the optimum conditions, the calibration graph exhibited linearity over the range of 0.5—500 ng/mL with the correlation coefficient(r) of 0.9996.The enrichment factor was 122 and the limit of detection was 0.1 ng/mL.The method was applied to the determination of copper in the complex matrix samples such as rice and millet with the recoveries for the spiked samples at 5.0 and 10.0 u,g/g falling in the range of 92.0-98.0%and the relative standard deviation of 3.9-5.7%.     

A novel microbial biosensor based on cells of <Emphasis Type="Italic">Gluconobacter oxydans</Emphasis> for the selective determination of 1,3-propanediol in the presence of glycerol and its application to bioprocess monitoring

Novel and selective microbial amperometric biosensors that use Gluconobacter oxydans cells to monitor the bacterial bioconversion of glycerol (Gly) to 1,3-propanediol (1,3-PD) are described. Two different mediators, ferricyanide and flexible polyvinylimidazole osmium functionalized polymer (Os-polymer), were employed to prepare two different microbial biosensors, both of which gave high detection performance. The good operational stabilities of both types of biosensor were underlined by the ability to detect 1,3-PD throughout 140 h of continuous operation. Both microbial biosensor systems showed excellent selectivity for 1,3-PD in the presence of a high excess of glycerol [selectivity ratios (1,3-PD/Gly) of 118 or 245 for the ferricyanide and Os-polymer systems, respectively]. Further, the robustness of each microbial biosensor was highlighted by the high reliability of 1,3-PD detection achieved (average RSD of standards <2%, and well below 4% for samples). The biosensor implementing the Os-polymer mediator exhibited high selectivity towards 1,3-PD detection and allowed moderate sample throughput (up to 12 h⁻¹) when integrated into a flow system. This system was used to monitor the concentration of 1,3-PD during a real bioprocess. Results from biosensor assays of 1,3-PD in bioprocess samples taken throughout the fermentation were in a very good agreement with results obtained from reference HPLC assays (R ² = 0.999).