Determination of total rare earth elements,thorium and chromium with 2-(2-arsenophenylazo)-1,8-dihydroxy-7-(2,6-dibromo-4-fluorophenylazo) naphthalene-3,6-disulphonic acid by reversed-phase ion-pair liquid chromatography

The retention behaviour of the complexes of rare earth elements, thorium and chromium with 2-(2- arsenophenylazo)-1,8-dihydroxy-7-(2,6-dibromo-4-fluorophenylazo)naphthalene-3,6-disulphonic acid was studied. Precolumn derivatization was used. The stationary phase was ODS-bonded silica and the mobile phase was methanol-water-tetrabutylammonium bromide. The detection limits are 2 ng ml^?1 for total rare earths, 2.5 ng ml^?1 for thorium and 10 ng ml^?1 for chromium. The tolerance of foreign ions is very high. The method can be applied satisfactorily to ore samples and rocks.     

2-(8-羟基喹啉-5-磺酸-7-偶氮)-1,8-二羟基-3,6-萘二磺酸与牛血清白蛋白的相互作用

用平衡透析法和分光光度法研究了 2 (8 羟基喹啉 5 磺酸 7 偶氮 ) 1,8 二羟基 3,6 萘二磺酸与牛血清白蛋白 (BSA)在酸性溶液中的结合反应 ,认为 8Q5SAC与BSA之间的结合力是以静电引力为主的非共键作用力 ,并探讨了其结合模型。在 2 98K下 ,测得这一反应的最大结合数为 35～ 40 ,结合常数为 6 .1× 10 5L mol。还研究了溶液基本条件如酸度和离子强度等对 8Q5SAC与牛血清白蛋白分子复合物形成的影响 ,在pH =3.34条件下 ,标准工作曲线的线性范围为 0 .2 0～ 46 .90mg L。     

钇与2-(4'-氯-2'-膦酰基-苯偶氮)-7-(2',6'-二溴-4'-氯-苯偶氮)-1,8-二羟基-3,6-萘二磺酸配位反应驰豫动力学研究

用跳浓驰豫法测定不同温度下的驰豫时间τ.根据拟定的机理导出了1/τ的函数表达式为1/τ＝k[H₆R]₀/[H₃⁺O]-(6k/ε[H₃⁺O]₀)A_∞,获得表观速率常数k及摩尔吸光系数ε,表观活化能为52.82KJ/mol,活化焓为50.34kJ/mol,活化熵在278K～298K范围内为负值,配合物稳定常数lgK'.为13.84。与孤立变量法、比尔法、平衡移动法获得的结果吻合.     

5-Cl-DEPAP作为铜的络合滴定指示剂的研究

对5-C-DEPAP作为络合滴定铜的指示剂进行了研究。在pH5.5的HAc-NaAc介质中,加入5滴5-Cl-DEPAP指示剂,以EDTA标准溶液对铜进行滴定,溶液颜色由紫红色变为黄绿色（铜量多时为绿色）,终点突跃敏锐,准确度高。方法用于化学试剂和铝合金中铜的测定。     

7-Amino-1-naphthol-3,6-disulphonic acid (2R-acid) as a chromophoric reagent for trivalent iron

Summary 7-Amino-1-naphthol-3,6-disulphonic acid forms a stable red coloured complex with trivalent iron. Studies on the composition and stability of this complex are described.

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Zusammenfassung 7-Amino-1-naphthol-3,6-disulfonsäure bildet mit Eisen(III) einen beständigen, rotgefärbten Komplex. Über die Untersuchungen zur Zusammensetzung und Stabilität dieses Komplexes wird berichtet.

     

Determination of Lead Using a New Chromogenic Reagent 2-(2-Sulfo-4-acetylphenylazo)-7-(2,4,6-trichlorophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic Acid

A novel chromogenic reagent, 2-(2-sulfo-4-acetylphenylazo)-7-(2,4,6-trichlorophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid 1, was prepared by diazo coupling of 4-acetylaniline-2-sulfonic acid and 2,4,6-trichloroaniline to chromotropic acid through –N=N– groups. Based on this reagent, a simple, sensitive and selective spectrophotometric method was developed for the determination of lead. In 0.20M phosphoric acid medium, lead reacts with 1 to form a 1:2 blue complex with an absorption maximum of 654nm. Beers law is obeyed in the range of 0–0.6mgL^–1 of lead. The apparent molar absorptivity is 1.25×10⁵Lmol^–1cm^–1. The detection limit and quantification limit were found to be 0.63µgL^–1 and 2.1µgL^–1, respectively. The relative standard deviation for eleven replicate measurements was of 2.6%. The interference of foreign ions was also investigated. All the other foreign ions studied did not interfere with lead determination except for Ca(II) and Ba(II). The interference caused by Ca(II) and Ba(II) can be eliminated by prior extraction of lead with potassium iodide-methylisobutylketone (KI-MIBK). The proposed method was applied to the determination of lead in certified samples with satisfactory results.     

Spectrophotometric determination of thorium in food using 2-(2,5-disulfonic-4-methoxyphenylazo)-7-(2-hydroxyl-5-carboxylphenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid

A new highly sensitive and selective chromogenic reagent, 2-(2,5-disulfonic-4-methoxyphenylazo)-7-(2-hydroxyl-5-carboxylphenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (1), was synthesized and applied to the spectrophotometric determination of trace thorium. In 5 mL of a 6 M perchloric acid medium, which greatly increases the selectivity, thorium reacts with 1 to form a 1: 2 green complex, having a sensitive absorption peak at 670 nm. Under optimal conditions, Beer’s law is obeyed over the range from 0 to 0.8 μg/mL Th(IV) and the apparent molar absorptivity is 2.09 × 10⁵ L/mol cm. It is found that, uranium(VI), Ti(IV), heavy rare earths, and most of other common metal ions do not interfere. The method has been tested on the determination of thorium in food samples with satisfactory results. The text was submitted by the authors in English.     

2-(8-quinolylazo)-7-phenylazochromotropic acid as an analytical reagent

2-(8-Quinolylazo)-7-phenylazochromotropic acid (QAPAC) has been synthesized by coupling diazotized 8-aminoquinoline with 2-phenylazochromotropic acid as well as by coupling diazotized aniline with 2-(8-quinolylazo)chromotropic acid. The properties of QAPAC and the spectrophotometric characteristics of some metal-QAPAC complexes are reported.     

Spectrophotometric determination of zirconium with 2-(1-hydroxy-4,6-dinitro-2-phenylazo)-1,8-dihydroxynaphthalene-3,6-disulphonate (picramine ca) as chromogenic reagent

The title compound has been used as a selective reagent for the micro-determination of zirconium in acidic medium (0.5MHCl) and found to be better than Picramine R. Spectrophotometric studies show the formation of a 2:1 (ligand:Zr) water-soluble complex and the reaction is suitable for photometric determination of 0.4-2.8 ppm of zirconium. The colour takes about 90 min to develop fully and is stable for about 20 hr. The molar absorptivity of the complex is 2.4 x 10(4) and the equilibrium constant is of the order of 10(10). The interference due to a number of ions has been studied.     

Kinetics of the formation of a complex of the palladium ion with 1,8-dihydroxy-2-(2-pyrazoline-5-azo) naphthalene-3,6-disulfonic acid

The kinetics of the complex-formation of the palladium ion with 1,8-dihydroxy-2-(2-pyrazolin-5-azo)naphthalene-3,6-disulfonic acid has been studied in aqueous solution (pH 0–5). It has been shown that the rate of the reaction is a maximum at pH 2.8 and falls at pH > 2.9 because of the hydrolysis of the palladium ions and at pH < 2.9 as a consequence of the protonation of the reagent molecule.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 5, pp. 611–613, September–October, 1985.     

4-(3,5-dichloro-2-pyridylazo)-1,3-diaminobenzene as a metallochromic indicator for the complexometric determination of Cu(II) with EDTA

In slightly acid solutions Cu(II) and 4-(3,5-dichloro-2-pyridylazo)-1,3-diaminobenzene (3,5-C12PADAB) form a red-purple complex( = 5.0 x 10(4)1.mole(-). cm(-1) at 547 nm). The complex is readily broken by EDTA, with a sharp change of colour to the yellow of the free reagent (Deltalambda(max) = 110 nm at pH 3.5). This colour contrast and the reversibility of the formation reaction, together with the solubility of the complex in water, make the pyridylazo reagent useful as a metallochromic indicator for copper titration, at pH 2.7-5.5. The Cu(II)-3,5-C12PADAB indicator system has been satisfactorily applied to the determination of sulphur in cast iron, "useful oxides" (Al(2)O(3) + Fe(2)O(3)) in samples of commercial aluminium sulphate, and total phosphorus in a synthetic mixed fertilizer.     

p-Sulphobenzeneazo-4-(2,3-dihydroxy-5-chloropyridine) as a spectrophotometric reagent for vanadium in steels

Vanadium(V) reacts quickly with the reagent to form a water-soluble orange-red 1:2 complex (λ_max = 495 nm ; ? = 2.5 × 10⁴ l mol^-1 cm^-1). The complex is used to determine 0.04–1.5% vanadium in steels.     

1-(2,3,4-Trihydroxybenzylideneamino)-8-hydroxynaphthalene-3,6-disulfonic acid as reagent for spectrophotometric determination of boron in plants

A highly sensitive and selective method has been developed for spectrophotometric determination of boron in plants, the method based on the color reaction of new reagent 1-(2,3,4-trihydroxybenzylideneamino)-8-hydroxynaphthalene-3,6-disulfonic acid (THBA) with boron (III). In an ammonium acetate solution of pH 8.0, boron(III) reacts with THBA to form a 1:2 yellow complex which has a maximum absorption peak at 430 nm. The reaction can complete within 90 min and the absorbance of the complex remains maximum and almost constant at least for 24 h under a temperature range from 0 to 35 °C. The apparent molar absorptivity and Sandell's sensitivity are 2.95 × 10⁴ l mol⁻¹ cm⁻¹ and 0.00036 ng cm⁻², respectively. The limit of quantification, limit of detection and relative standard deviations were found to be 5.1, 1.5 ng ml⁻¹ and 1.12%, respectively. Under the optimum conditions, the absorbency of the complex (λ_max = 430 nm) increases linearly with concentration up to 0.8 μg ml⁻¹ of boron(III). The influences of foreign ions on the determination of boron were investigated in detail. Most of foreign ions can be tolerated in considerable amounts. Experiments have indicated that THBA as chromogenic reagent for spectrophotometric determination of boron has excellent analytical characteristics. Its sensitivity is more than 4.2-fold that of azomethine-H, and stability is advantage over other derivatives of azomehine-H remarkably. Moreover, the synthesis of THBA and its physicochemical properties of THBA were also investigated in detail. Proposed method has been applied to the determination of boron in plants with satisfactory results.     

1-(1,2,4-Triazolyl-3-azo)-2-naphthol as a spectrophotometric reagent for inorganic ions

The synthesis, characteristics and analytical reactions of 1-(1,2,4-triazoly 1-3-azo)-2-naphthol are described. Coloured complexes are formed with 21 metal ions. For the cadmiuin(II) complex, the molar absorptivity is 2.8 × 10⁴ 1 mol^-1 cm^-1 at 515 nm for 40% ($\text{v}\text{v}$) ethanolic solutions at pH 8.0. For the mercury(II) complex at pH 10, the molar absorptivity is 2.7 × 10⁴ mol^-1 cm^-1 at 530 nm. Complexes of the ML₂ type are formed.     

1-(2-hydroxy-3-methoxybenzylideneamino)-8-hydroxynaphthalene-3,6-disulfonic acid as a reagent for the spectrophotometric determination of boron in ceramic materials

A sensitive and selective spectrophotometric method for the determination of boron is described. The method is based on the colour reaction between boron and the reagent 1-(2-hydroxy-3-methoxybenzylideneamino)-8-hydroxynaphthalene-3,6-disulfonic acid (HMOA). In a HOAc-NH4OAc buffer of pH 5.5, HMOA reacts with boron to form a 1:2 yellow complex with a maximum absorption at 423 nm. The absorbance (lambdamax = 423 nm) is linear up to 1.2 microg ml(-1) boron in aqueous solution with a repeatability (RSD) of 1.12%. The molar absorptivity and Sandell's sensitivity are 7.19 x 10(3) l mol(-1) cm(-1) and 0.0015 microg cm(-2), respectively. The limit of quantification and limit of detection were found to be 17.1 and 5.2 ng ml(-1), respectively. The interference of various ions was examined in detail. All the metal ions studied can be tolerated in considerable amounts; in particular, the tolerance limits of Fe, Al, Zn, Ca and Mg are superior to those of other reagents such as Azomethine-H and Azomethine-HR. The proposed method was applied to the determination of boron in ceramic materials with satisfactory results.     

PAN-6S作络合指示剂连续滴定测定汞和铅的研究

试验研究了pH3.0和pH5.4的介质中,以1 (2 吡啶偶氮) 2 萘酚 6 磺酸(PAN 6S)作为指示剂,以EDTA为滴定剂连续滴定汞和铅,其终点颜色变化敏锐,准确度高。     

钙与 DBC-偶氮氯膦显色反应的研究及其在高纯氧化钇中钙的测定的应用

在PH8.5-9的液中,钙可与DBC-偶氮氯膦形成一种紫色的稳定配合物。该配合物在625nm处有最大吸收,表观摩尔吸光系数为2.6×10~4L.mol~(-1).cm~(-1),配合物组成为Ca:DBC-偶氮氯膦=1:1。在Zn-DTPA和乙二胺的存在下,较大量的Y~(3+)、Fe~(3+)及Cu~(2+)、Mo(Ⅵ)、Cr~(3+)等三十余种离子不干扰钙的测定。方法的选择性较好,利用本方法,并经简单萃取分离基体后,测定了高纯氧化钇和易切削钢中的微量钙,结果令人满意。标准加入试验回收率好。方法简便实用。     

Spectrophotometric and potentiometric study of the complexes originated by the trisodium salt of 2-(p-sulfophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (SPADNS) and several metal ions

A study of the complexes originated by U(VI), Cu(II), Pb(II), Ni(II), Co(II), Zn(II), Cd(II), Mn(II), Ca(II), Mg(II), Ba(II), and Sr(II), and SPADNS (trisodium salt of 2-(p-sulfophenylazo)-1, 8-dihydroxynaphthalene-3,6-disulfonic acid) has been made by means of spectrophotometric and potentiometric methods. The dissociation constants of the ligand and the formation constants of the metal ion-SPADNS complexes have been determined at 25 ± 0.1 °C and ionic strength 0.1 (NaClO₄).     

4-(N,N-dimethylaminosulphonyl)-7-fluoro-2,1,3-benzoxadiazole as chemilumigenic reagent for high performance liquid chromatographic peroxyoxalate chemiluminescence detection

4-(N,N-Dimethylaminosulphonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F), presented as a fluorogenic labelling reagent for amines and amino acids, is preferred for peroxyoxalate chemiluminescence (PO-CL) detection in high performance liquid chromatography. Amino acids and epinephrine derivatized with DBD-F were separated on a reversed phase column and detected at the femtomole level by the PO-CL detection system.     

2－［2－苯骈噻唑偶氮］－5－二乙氨基苯甲酸作为络合滴定铜的指示剂的研究

本文研究了ＢＴＡＥＢ作为络合滴定铜的指示剂的分析性能。结果表明，在ｐＨ４．０～６．５范围内，目视滴定０．３～５００ｍｇ铜，终点由蓝色变为紫红色，变色敏锐，准确度高。应用于锡磷青铜和深井泵叶轮合金中铜的分析，结果个人满意。