Sensitive spectrophotometric determination of La(III) with 1-(2-pyridylazo)-2-naphthol

A simple and sensitive method for spectrophotometric determination of lanthanum has been developed. At pH 9.6, in presence of 50% ethanol, lanthanum reacts with 1-(-2-pyridylazo)-2-naphthol (PAN) to form a red complex which has two absorption maxima, at 545 and 510 nm. The molar absorptivity at 545 nm is 0.55 × 10⁴ liters · mol^?1 cm^?1. On the other hand, lanthanum reacts with PAN in pure ethanol to form a red complex at 530 nm, with high molar absorptivity (8 × 10⁴ liters · mol^?1 cm^?1).     

共振光散射法测定丁胺卡那霉素

研究了以达旦黄（TY）作为共振光散射探针测定市售药品中丁胺卡那霉素（AMK）的测定方法．该方法基于在pH=5．5的Britton—Robinson缓冲溶液中,达旦黄和丁胺卡那霉素结合后有强烈的共振光散射作用．在λ=482nm处,共振光散射强度（△IRLS）最大且光散射的强度与AMK的浓度在0．4～2．4mg·L^-1范围内成正比（相关系数r=0．9986）,检出限为8．6×10^-3mg·L^-1．该方法简便、快速、灵敏,对1．0mg·L^-1的AMK溶液平行测定11次,RSD=2．57％．用于市售样品的分析测定,结果满意。     

Tüpfelnachweis von Magnesium

Zusammenfassung Diazotiertes p-Nitroanilin gibt mit Ammoniumhydroxid einen gelben Niederschlag, der sich in alkalischem Medium rot färbt. Dieses Reagens kann in alkalischem Milieu zum Tüpfelnachweis von Magnesium angewendet werden. Auch Nickel gibt die Reaktion, aber nur in geringerem Maß. Die mit Alkali fällbaren Metalle müssen vorher entfernt werden. Alkaliund Erdalkalimetalle stören den Nachweis nicht. Der Nachweis der Struktur des Reagens wird eingehend beschrieben.

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Spot test detection of magnesium

Summary Diazotizedp-nitroaniline yields a yellow precipitate with ammonium hydroxide and this product turns red in alkaline medium. This reagent in an alkaline milieu may be employed for the spot test detection of magnesium. Nickel likewise gives this reaction, but only to a slight extent. The metals that can be thrown down with alkali must be removed beforehand. Alkali and alkaline earth metals do not interfere with the test. The question as to the structure of the reagent was been studied in detail.

     

Spectrophotometric determination of cobalt and nickel with Pyridine-2-Aldehyde-2-Quinolylhydrazone

Pyridine-2-aldehyde-2-quinolylhydrazone (PAQH) is a selective and sensitive reagent for cobalt or nickel. The reagent reacts with only a few metals to give coloured complexes; with the exception of palladium, the cobalt chelate is the only complex relatively stable towards protons and PAQH is a very selective reagent for cobalt. In the presence of thioglycollic acid only nickel reacts with PAQH; the chelate is extracted with chloroform and its absorbance measured at 492 nm. The high molecular extinction coefficients (30·10³ and 51·10³) permit the determination of 0.2–2 p.p.m. of cobalt and 0.1–1 p.p.m. of nickel.     

The color reactions of sulfonazo-III isomers with lanthanum and alkaline earth metal ions

Six sulfonazo-III isomers were synthesized, and their color reactions with alkaline earth metals and lanthanum investigated. All six reagents had good sensitivities for lanthanum (? = 1.9–5.0·10⁴), but the sensitivities for alkaline earth metals were fairly low except for the barium chelate of sulfonazo-III (? = 2.8 · 10⁴). The position of the sulfo group on the phenyl ring and the symmetry of the reagent are important for the barium reactions, but of little significance for the lanthanum reactions. The effects of water-miscible solvents are also described.     

Colorimetric determination of magnesium

From a critical study of the colorimetric determination of magnesium with titan yellow we concluded that: a. titan yellow must be present in excess; b. a mixture of glycerol and starch solution is satisfactory as protecting colloid; c. the influence of calcium becomes constant with concentrations 10 mg Ca⁺² per 100 ml; d. aluminium, iron, phosphate, ammonium and silica interfere; e. alkali-ions interfere when present in large quantities.The method is rapid and the accuracy is satisfactory and can be recommended for the determination of Mg⁺² in water and in silicates.     

Beiträge zur Chemie der Alkylverbindugen von Übergangsmetallen. XXIX. Dibenzylmangan – Darstellung und Reaktionen

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XXIX. Dibenzyl Manganese – Preparation and Reactions Manganese(II) acetylacetonate reacts with tribenzyl aluminium and dibenzyl magnesium forming the yellow complexes 3(C₆H₅CH₂)₂Mn · Al(acac)₃ and (C₆H₅CH₂)₂Mn · Mg(acac)₂ Dibenzyl manganese is also formed at the reaction of dibenzyl magnesium or benzyl magnesium chloride with MnCl₂ · 1.5 THF and was separated as the dioxan complex (C₆H₅CH₂)₂Mn · 2C₄H₈O₂, the ligands of which can be removed to a great extent in vacuum. Dibenzyl manganese reacts with CO₂, CS₂ and SO₂ with insertion into the Mn–C-bonds. The corresponding manganese compounds were isolated and furtherly characterized.     

N-bromosuccinimide-fluorescein system for the determination of protein by flow injection chemiluminescence

A method for flow injection with chemiluminescence (CL) detection has been developed for the determination of proteins. It is based on the luminescence of the N-bromosuccinimide-fluorescein-protein system, where fluorescein is used as an energy transfer reagent in alkaline medium. The CL of the system is strongly enhanced by hexadecyl trimethyl ammonium bromide. Optimum conditions and possible mechanisms have been investigated. Under optimum experimental conditions, the linear range is from 0.4 to 40 µg·mL^?1 for egg albumin, 0.2 to 20 µg·mL^?1 for bovine serum albumin, and from 1 to 100 µg·mL^?1 for bovine hemoglobin. The detection limits are 37, 62, and 240 ng·mL^?1, respectively.     

Coupled multisyringe flow injection/reactor tank for the spectrophotometric detection of azinphos methyl in water samples

A multisyringe flow injection system with spectrophotometric detection is presented as a fast, robust and low-reagent consumption system for the determination of azinphos methyl (AzMe) in water samples. Determination is based on the Griess reaction. The analyte is hydrolyzed and the reaction product reacts with nitrite in acid medium to form the diazonium salt that reacts further with 1-naphtol reagent to produce an azo compound. The azo derivative is spectrophotometrically monitored at 485 nm. The influence of several chemical and flow variables has been investigated. Under the optimum analytical conditions, the linearity of the calibration curve for AzMe ranges from 1 to 32 μg mL^?1. The detection limit is 0.17?µg mL^?1, and recoveries between 95 to 109% have been obtained. The repeatability (RSD) is 0.8% for a 10?μg mL^?1 solution, and the injection throughput is seven samples h^?1. The system has been satisfactorily applied to the determination of AzMe in spiked river and dam water samples. The results were in agreement at the 95% confidence level with those obtained by HPLC.     

Hydration of medium reactive industrial magnesium oxide with magnesium acetate

Medium reactive magnesium oxide reacts incompletely with available water to form magnesium hydroxide. To enhance the hydration of medium reactive magnesium oxide, the effect of magnesium acetate as hydrating agent was studied. The extent to which different parameters (concentration of magnesium acetate, solution temperature and solid to liquid ratio of MgO to magnesium acetate) influence the hydration rate of a medium reactive industrial sample of magnesium oxide were evaluated. The degree of rehydration measured as percentage Mg(OH)₂being formed, increases from approximately 56% using 0.5 M magnesium acetate solutions at 25°C to 64% at 50°C, to more than 70% at 70°C. The major part of rehydration of the medium reactive MgO sample occurs within the first few minutes of the reaction for all three temperatures studied. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spectrophotometric determination of copper and iron and analysis of their mixtures by means of biacetyl (2-Pyridyl)hydrazone thiosemicarbazone

Summary Spectrophotometric Determination of Copper and Iron and Analysis of Their Mixtures by Means of Biacetyl (2-Pyridyl)hydrazone Thiosemicarbazone Biacetyl (2-pyridyl)hydrazone thiosemicarbazone (BPHT) has been examined to evaluate its usefulness as a selective Spectrophotometric reagent for iron and copper. Iron(II) reacts with BPHT, yielding a green complex in weakly acid medium. Copper(II) and BPHT form yellow or red complexes in acid or alkaline media, respectively. In addition, both ions can be determined simultaneously. The methods have been applied to the determination of copper and iron in ores and alloys, and their mixtures in pharmaceutical preparations.     

Analytical applications of picolinealdehyde salicyloylhydrazone: II. Extraction and spectrophotometric determination of vanadium(V)

Picolinealdehyde salicyloylhydrazone reacts with vanadium(V) to produce a yellow 1:1 complex (λ_max = 400 nm, ? = 2.17 × 10⁴ liters · mol^?1 cm^?1) in aqueous ethanolic solution. The yellow complex can be extracted into chlorobenzene (λ_max = 425 nm, ? = 2.16 × 10⁴ liters · mol^?1 cm^?1) and used for the spectrophotometric determination of trace amounts of vanadium. Interferences have been investigated. The method has been applied to the determination of vanadium in steel and in lead concentrates.     

Novel Method for Selective Spectrophotometric Determination of Titanium(IV) with Water Extract of Slippery Elm Leaf as a New Reagent

Abstract

A novel spectrophotometric method for the determination of titanium(IV) by using a new reagent, water extract of slippery elm leaf is developed. In 0.05 M hydrochloric acid, titanium(IV) reacts with this reagent to form a yellow product. The formed product shows maximum absorbance at 415 nm with a molar absorptivity value of 0.68×10⁴ l mol^–1 cm^–1 and the method was linear in the 0.2–6 µg ml^?1 concentration range. The detection limit value was found to be 0.0131 µg ml^?1. The proposed method was simple, low cost, selective, and sensitive. It was applied to the analytic samples with satisfactory results.     

Application of acidic extract of Platanus orientalis tree leaves as a green reagent for selective spectrophotometric determination of zirconium

Abstract

A novel spectrophotometric method for the determination of zirconium by using a new reagent, acidic extract of Platanus orientalis tree leaves is developed. In 6 M hydrochloric acid, zirconium reacts with this reagent to form a yellow product. The formed product shows maximum absorbance at 422 nm with a molar absorptivity value of 0.59×10^? l mol^?1 cm^?1 and the method was linear in the 0.4–8 µg mL^?1 concentration range. The detection limit value was found to be 0.086 µg mL^?1. The proposed method was simple, clean, low cost, selective, and sensitive. It was applied to the determination of zirconium in tap water, wastewater and well water samples with relative standard error of less than 2.5%.     

Biomimetic aminoacylation of ribonucleotides and RNA with aminoacyl phosphate esters and lanthanum salts

Aminoacylation of tRNA in cells involves activation of the amino acid as an aminoacyl adenylate, a mixed anhydride with AMP, which reacts with tRNA. We have now established that aminoacyl phosphate esters in the presence of lanthanide ions in water will acylate hydroxyls at the 3'-terminus of RNA or a simple nucleotide. By extension, this will permit synthetically aminoacylated tRNA to be produced in a single-step biomimetic process. The reactions of Boc-4-fluorophenylalanyl ethyl phosphate were followed by HPLC separation, MS, and 19F NMR analysis. In stoichiometric combination with lanthanum salts in aqueous buffer, Boc-4-fluorophenylalanyl ethyl phosphate rapidly produces 2'- and 3'-monoesters of cytidine and cytidine monophosphate. Reaction of the reagent with RNA in the presence of lanthanum and magnesium salts introduces a specifically detectable signal into the RNA, which is evidence of formation of the aminoacyl ester. When the same RNA is initially oxidized with periodate to convert the 3'-terminal vicinal diol to the cleaved dialdehyde, reaction with the aminoacyl phosphate no longer occurs as evidenced by the lack of a signal in the 19F NMR spectrum. The results are consistent with a requisite chelation mechanism in which lanthanum serves as a template for both the aminoacyl phosphate and the 3'-terminal diol of RNA and nucleotides. The coordinated diol will then react through specific base-catalyzed intramolecular addition of the alkoxide nucleophile to the acyl group of the aminoacyl phosphate. Assessment of the method with a single tRNA was also achieved using the fluorescent reagent N-dansyl-glycyl ethyl phosphate. Lanthanide-promoted aminoacylation at the 3'-terminus of tRNAPhe is detected by the introduction of fluorescence (detected directly and by antibody-enhanced emission). This does not occur if the 3'-terminus is converted to the dialdehyde by reaction with periodate.     

微波等离子体炬原子发射光谱法测定铁增敏效应

针对在低功率下工作的微波等离子体炬原子发射光谱法(MPT-AES)存在对一些元素检测灵敏度较低和抗基体干扰能力弱的问题,以氩气为载气和工作气,研究了表面活性剂及镧盐对MPT-AES测定铁的增敏效应,考察了铁测定的工作条件和共存元素对铁测定的影响.实验结果表明,非离子表面活性剂对铁的测定有抑制作用,而阳离子表面活性剂和镧盐对铁的测定有增敏作用,其中镧盐增敏效果最好.以镧盐为增敏剂,不仅可提高MPT-AES测定铁的灵敏度,还可增加共存元素的允许量.当体系中镧浓度为0.500 mg/m L时,至少可使40倍的锌,30倍的钴,20倍的镍、锰,15倍的钙,10倍的镁、铜和钠不影响铁的测定.与不加镧时相比,铁的发射强度提高了2.4倍,检出限由原来的27.5×10~(-3)μg/m L下降为8.5×10~(-3)μg/m L.将本方法应用于原油样品中铁的测定,所得结果与火焰原子吸收光谱法测定结果一致.     

Fluorimetric determination of boron at microgram level

The synthesis, characterization and application of 2-(2-hydroxybenzylidenimine)benzene-arsonic acid (HBBA) as a reagent for the fluorimetric determination of boron are described. This reagent reacts with boric acid in 85% w/w sulphuric acid medium to yield a fluorescent compound. The reagent is not fluorescent in those conditions. Heating at 90 degrees for 45 min is needed for the compound to be formed. The linear calibration range is 0.1-8 microg/ml in the solution measured. The detection limit of the method is 0.01 microg/ml. The method has been applied to determine boron in vegetal material.     

A Clean,Sensitive and Lasting New Spot Test for Paper and Thin-Layer Chromatograms of Perbromate Ion

Abstract

Benzidine in dilute acetic acid reacts with perbromate ion to give initially a blue colored spot which, on further heating, changes to a dark bluish-grey spot. The latter serves as a sensitive clean test for the detection of perbromate ion on paper and thin-layer chromatograms and electrophoregrams. The reagent can also be used to detect bromate, iodate and periodate ions as well as free halogens.     

Development of a novel colorimetric indicator pad for detecting aldehydes

A colorimetric indicator was developed and a colorimetric indicator pad was fabricated for the rapid detection of aldehydes. The detection pad has two sides: an observation side on top and a barrier on the bottom. The top side contains a reagent which reacts directly with aldehydes to produce a color change, while the bottom side is coated with a double-sided plastic tape barrier to prevent the escape of chemicals. Sensitivity of the indicator pads was determined using the vapor sensitive ASTM F739 technique with the presence of the indicator. A significant indicator color change (yellow to red) occurred about 5 min before the infrared analyzer response of the ASTM method. The chemical principle and reaction characterization of the test are described. The stability and potential interferences of the indicator pad were also examined by directly spiking aldehydes and compounds with other functional groups, respectively, onto the indicator pads. The newly developed aldehyde indicator pad should find utility in detecting aldehydes in both liquid and vapor phases and in collecting aldehyde permeation through PPE for further study.     

荧光光谱法测定饮料中氨基酸的含量

采用荧光分光光度法测定游离氨基酸。在pH=6.0的乙酸-乙酸钠缓冲溶液中,氨基酸与乙酰丙酮-甲醛体系反应,产生黄绿色荧光,试验了体系酸度、试剂加入次序及用量、反应温度、反应时间对体系荧光强度的影响。以丙氨酸为例进行试验,丙氨酸浓度与体系荧光强度在1.0~20.0μg/mL范围内有良好的线性关系,检出限为0.05μg/mL。