Inorganic analysis in organic solvents : 8-hydroxyquinaldine as a reagent for the determination of copper

A new method is descibed forthe determination of copper. Fom a suitable solution, copper is extracted as its 8-hydroxyquinaldine complex into chloroform. The solution is diluted with an equal volume of benzene and passed through an activated alumina chromatographic column, whereupon all the 8-hydroxyquinaldates, except that of chromium, are adsorbed. Copper is eluted completely by developing the column with a 0.5% solution of 8-hydroxyquinaldine in that solvent mixture. The optical density of the cluate is measured at 400 mμ with respect to the solvent. Iron, molybdenum and vanadium interfere, but interference due to iron and molybdenum is readily overcome by a simple preliminary treatmont.     

水溶性电泳漆溶剂中有机成分的气相色谱分析

异丙醇,正丁醇,乙二醇单丁醚均为水溶性电泳漆溶剂中添加的有效成分,其含量的大小影响金属件着漆效果及经济成本,其中乙二醇单丁醚是电泳漆中高沸点溶剂,用作分散剂、湿润剂[1,2]。本文在文献[3,4]的基础上,考察了三种成分的气相色谱分离,确定了测定条件。1　实验部分1 1　仪器与测试条件日本产岛津GC-9A型气相色谱仪带C-R3A型色谱数据处理机。FID为检测器,1 6m×3 2mm玻璃柱,固定相GDX-103(60 80目),气化温度200℃,检测温度250℃,柱温144℃。载气:氮气50ml/min,氢气40ml/min,空气450ml/min。以保留时间定性,采用内标乙二醇单乙醚…     

Spectrophotometric determination of water in organic solvents with solvatochromic dyes

The correlation between the absorbance at a fixed wave-length of a betaine dye in an organic solvent and the water content of the same solvent has been investigated. The betaine dyes investigated are 2,4,6-triphenyl-N-(3,5-diphenyl-4-hydroxyphenyl)pyiidinium betaine (I), 1-methyl-8-hydroxyquinolinium betaine (II), 1-methyl-6-hydroxyquinolinium betaine (III) and 2-methyl-5-isoquinolinium betaine (IV), and the organic solvents are ethanol, isopropanol, acetone, dioxan, acetonitrile and pyridine. The possibility of determining a trace amount of water in an organic solvent is demonstrated. The sensitivity of the method depends on solvent and dye but for example, 0.06 mg of water in 1 ml of acetonitrile can be detected with III with an ordinary spectrophotometer. The limitations of practical applications are discussed.     

Spectrophotometric determination of water in organic solvents with solvatochromic dyes-II

The correlation between the absorbance of a merocyanine dye in an organic solvent and the water content of the solvent has been investigated. The merocyanine dyes investigated are 1-methyl-4-[(4-oxocyclohexa-2, 5-dienylidene)-ethylidene]-1,4-dihydropyridine (I), 1-methyl-4-[(2-oxocyclohexa-3,5-dienylidene)-ethylidene]-1, 4-dihydropyridine, 1-methyl-2-[(4-oxocyclohexa-2,5-dienylidene)-ethylidene]-1, 2-di-hydropyridine and 1-methyl-2-[(oxocyclohexa-3,5-dienylidene)-ethyl-idene]-1, 2-dihydropyridine, and the organic solvents are isopropanol, acetone, acetonitrile and pyridine. The possibility of determining a trace amount of water in an organic solvent is demonstrated, and a procedure is proposed for the determination of trace water in pyridine. The sensitivity of the method depends on the solvent, being more sensitive in an aprotic solvent than in a protic one ; for example, 0.05 or 0.27 mg of water in 1 ml of acetonitrile or of isopropanol respectively can be detected with I, by use of an ordinary spectrophotometer.     

Inorganic polarography in organic solvents

A review of inorganic polarography in organic solvents is presented.     

Spectrophotometric determination of trace water in organic solvents with a near infrared absorbing dye

A spectrophotometric method for the determination of trace water in organic solvents using a near infrared absorbing dye has been developed. This method is based on the effect that a minor change in polarity of the solvent caused by trace water content determines the extent of aggregation of a near-infrared dye monomer. This change can be detected spectrophotometrically. The calibration curves for methanol, ethanol, and isopropanol were determined. This method has the highest sensitivity (em = 16.73 unit) for water in isopropanol and the lowest sensitivity (em = 2.806 unit) for water in methanol. The correlation coefficient (R)(2) values for the regression lines ranges from 0.990-0.998. The linear range of the method for ethanol is 0.001-0.5%, for isopropanol is 0.001-0.1%, and for methanol is 0.001-1.0%. The limit of detection for ethanol, isopropanol, and methanol are 0.0001, 0.0001, and 0.005% water, respectively. The developed method is sensitive, simple and easy to operate, and the cost of analysis is low.     

Spectrophotometric determination of traces of water in organic solvents (oxygen-free molecules)

Spectrophotometry and potentiometry have been used to determine the self-ionization product of formic acid and the acidity constants of hydrobromic, hydrochloric, methanesulfonic, p-toluenesulfonic, sulfuric, trifluoroacetic, pieric and benzoic acids in formic acid.     

Sample preparation for gas chromatographic analysis of organic solvents in aerosol cans

Summary A method for the sampling of chemical products from aerosol cans is described. An aerosol can is frozen in liquid nitrogen, followed by puncturing the can and allowing the propellant to distill off. The conditions for the smaple preparation have been optimized. Solvent content in the products were analysed by headspace gas chromatography-mass spectrometry.     

Rapid separation and determination of chromium

Chromium(III) is oxidized to chromium(VI) at room temperature or by conventional persulphate oxidation. The chromium(VI) is separated from other metal ions by retention on a small anion-exchange column, and then eluted with a perchlorate solution and measured spectrophotometrically with a flow-through cell. The method is rapid, selective and amenable to automation.     

Spectrophotometric determination of chromium in waste water and soil

The reaction of Cr(VI) with o-nitrophenylfluorone (NPF) in presence of cetyltrimethyl-ammonium bromide (CTMAB) to form a purplish red complex at pH 4.7-6.6 by heating at 50 degrees for 10 min has been investigated. The composition of the complex is 1:2:2 [Cr(VI):NPF:CTMAB], the wavelength of maximum absorbance is 582 nm. The molar absorptivity is 1.11 x 10(5)1.mole(-1).cm(-1). Beer's law is obeyed up to 0.2 microg ml Cr(VI) concentration. The interference of several ions, including Cu(2+), Fe(3+) and Al(3+), is eliminated by addition of a masking mixture containing KF, DCTA and tartrate. A new sensitive method for determination of chromium in waste water and soil is presented.     

Spectrophotometric determination of chromium with 1,2-diaminocyclohexanetetraacetic acid

Chromium(III) forms a water-soluble complex with DCTA. The violet complex has maximum absorbance at 540 mμ and obeys Beer's law from 2 to 150 μg chromium per ml. The molar extinction coefficient is 245. Determinations of copper and chromium, cobalt and chromium, and nickel and chromium in presence of each other are described. The complex contains chromium and the reagent in a ratio of 1 : 1. The stability constant of the complex is 1.9·10²².     

Ion-pair chromatographic determination of chromium(VI)

Ion-pair chromatography (IPC) with conductometric detection was investigated as a precise and selective analytical method for the determination of chromium in electro-plating solutions and waste waters. Chromatographic parameters were optimized for separation of Cr(VI) and SO(2-)(4). The analytical column (100 x 6 mm) was packed with 10 mum silasorb C(18) (Czechoslovakia). Tetrabutylammonium butyrate (TBAB), at pH 7.0 in acetonitrile-water (18:82 v/v) mixture, was used as the eluent. Two samples of solution are taken for the analysis. In the first of them the amount of Cr(VI) is determined, in the second one Cr(III) is oxidized to Cr(VI) with H(2)O(2) in alkaline medium and the total amount of Cr is determined. From the difference of the two obtained results the concentration of Cr(III) is calculated. The detection limit of Cr(VI) is 0.1 mug/ml and the relative standard deviation (at the 1.0 mug/ml) is 4.0%. The IPC results for chromium agreed closely with these obtained by spectrophotometry.     

Colloid-chemical studies with nickel and chromium soaps in organic solvents

Summary Viscometric, spectrophotometric and solubility measurements have been made to study the colloidchemical behaviour of chromium and nickel soaps (stearate, palmitate, myristate and laurate) in a number of organic solvents. The experimental results have been sucessfully employed to determine the c.m.c. and the concentration of these metal soaps. Nickel stearate has been found to undergo thixotropic gelation in toluene.     

Spectrophotometric determination of chromium(VI) with ferron

Chromium(VI) gives a pink coloured solution in chloroform in the presence of ferron when extracted from slightly acidic medium. This reaction is used for the spectrophotometric determination of chromium by measuring the absorbance at 510 nm. Beers law is obeyed in the range of 5–70 g/ml. Most of the important metal ions do not interfere. The relative standard deviation is 2.78%.     

Spectrophotometric determination of chromium(iii) with complexans

Selective spectrophotometric determinations of milligrain amounts of chromium(III) with complexans are described, based on the fact that the chromium(IIl) complexes are formed rapidly at boiling temperatures, but very slowly at room temperature, while the formation of some interfering complexes takes place instantaneously. Determinations with EDTA are more sensitive, but the combined presence of cobalt and other metals still interferes; there is no interference with the less sensitive NTA. The combined presence of a l00-fold amount of copper, nickel, cobalt and iron generally has no effect on the results. The use of DCTA, DTPA and HEDTA is discussed.     

海水中有机污染物的光度法测定

海水中有机污染物在强碱性条件下被KMnO4所氧化。通过对生成物溶液中K2MnO4浓度的光度法测量（λ=430nm）,直接测定海水中有机物含量（以COD表示）。该方法的线性范围为0．40—4．50mg／L（以邻苯二甲酸氢钾＋甲酸钠体系为标准混合物溶液）,测定海水COD的相对标准偏差RSD为8．9％,回收率为90％～114％。     

催化动力学光度法测定铬的研究

在稀HCl介质中,微量铬(Ⅲ)对K2S2O8氧化酸性大红GR的褪色反应有明显的催化作用。据此建立了催化动力学光度法测定微量铬(Ⅲ)的新方法。确定了反应的最佳条件,并讨论了动力学参数。方法线性范围为0.008~0.4mg/L,检出限为2.96×10-6g/L。方法已用于自来水、钢厂废水、污水中微量铬(Ⅲ)的测定。     

Emission spectrochemical determination of chromium in organic acids

An emission spectrochemical procedure is described which directly determines the chromium concentration in organic materials in the p.p.m. range. The only preparation of the sample which is necessary is dilution with a graphite matrix which contains the internal standard element and the spectral buffer, lithium carbonate. The effect of sodium on spectral line intensities of cobalt and chromium is shown. The effectiveness of lithium carbonate as a spectral buffer is illustrated. The precision of the technique is estimated to be ± 11.8% and the accuracy estimated to be 10.9%.     

Inorganic polarography in organic solvents-IV: polarography of metal oxinate complexes in various solvents

The polarography of 24 metal oxinate complexes extracted into chloroform, IBMK, and ethyl acetate has been investigated, a methanolic solution of lithium chloride being used as base electrolyte. Only 15 complexes gave rise to reduction waves, and interference-free determinations have been developed for indium and thallium(III) in chloroform, and for bismuth, molybdenum and uranium in IBMK. The use of ethyl acetate offered no special advantages, and was the least selective of the three solvents used.