Differential determination of antimony(III) and antimony(V) by solvent extraction-spectrophotometry with mandelic acid and Malachite Green, based on the difference in reaction rates

Highly sensitive and reproducible extraction-spectrophotometric methods for differential determination of antimony(III) and antimony(V) were investigated. It was found that antimony(III) reacts easily with mandelic acid to form a complex anion extractable into chlorobenzene with Malachite Green from weakly acidic media (pH 2.2-3.5) at room temperature, whereas antimony(V) reacts only slowly, and heating for 15 min at 45 degrees is needed to obtain maximum sensitivity. The significant difference between the rates of reaction of mandelic acid with antimony(III) and antimony(V) was applied to the differential determination of these two species. The calibration graph was linear over the range 0.15-6.0 mug for antimony(III), and 0.20-10 mug for antimony(V).     

Extraction and spectrophotometric determination of molybdenum(VI) with Malachite Green and p-chloromandelic acid

Molybdenum(VI) reacts with p-chloromandelic acid to form a complex extractable into chlorobenzene with Malachite Green, from aqueous solution at pH 2.0-4.0 at room temperature, and can then be determined indirectly by measuring the absorbance of the Malachite Green in the extract, at 630 nm. The calibation graph is linear for molybdenum over the range 0.26-10.0 x 10(-6)M (0.10-4.0 mug); the apparent molar absorptivity is 1.06 x 10(5) l.mole(-1).cm(-1). The method has been applied to the determination of molybdenum in mild steels with satisfactory results.     

Extraction and spectrophotometric determination of titanium(IV) with malachite green and p-chloromandelic acid, with application to mild steels

A very sensitive, selective and simple method for extraction and spectrophotometric determination of titanium(IV) with an alpha-hydroxy acid has been developed. p-Chloromandelic acid reacts with titanium in weakly acidic aqueous solution at room temperature to form a complex anion extractable into chlorobenzene with Malachite Green as counter-ion. Titanium is determined indirectly by measuring the absorbance of Malachite Green in the extract at 630 nm. The calibration graph is linear for titanium(IV) over the range 0.25-7.5muM (0.05-1.44 mug); the apparent molar absorptivity is 1.31 x 10(5) l.mole(-1).cm(-1). The method has been successfully applied to the determination of titanium in mild steels.     

Inverse voltammetry of antimony with triphenylmethane dyes

A method is suggested for the determination of traces of antimony by inverse voltammetry of the solid phases formed with triphenylmethane dyes (Crystal Violet, Methyl Violet and Malachite Green) as the precipitants. The authors have studied the effect of concentration, adsorption and oxidation of the triphenylmethane dyes, potential and time of pre-electrolysis, and concentration of antimony(III) and some other elements on the polarogram shape and stripping current. A method for determining antimony traces in chromic salts is described as an example.     

Coulometric titration of bases in acetic acid and acetonitrile media

The working conditions and the results for coulometric titration of milligram amounts of some bases in 0.1M sodium perchlorate in a mixture of acetic acid and acetic anhydride (1:6), are given. Determinations were made both by coulometric back-titration or direct titration at the platinum anode. Back-titration was done in the catholyte, by coulometric titration of the excess of added perchloric acid. The titration end-point was detected photometrically with Crystal Violet as indicator. The direct titration of bases was done at the platinum anode, in the same electrolyte, to which hydroquinone was added as anode depolarizer and as the source of hydrogen ions, Malachite Green being used as indicator. Similarly, bases can be determined in acetonitrile if sodium perchlorate, hydroquinone and Malachite Green are added to the solvent. Errors are below 1 %, and the precision is satisfactory.     

Solvent extraction-spectrophotometric determination of phosphate with molybdate and malachite green in river water and sea-water

Molybdophosphate, formed between orthophosphate and molybdate in sulphuric acid solution, is extracted into a mixture of toluene and 4-methylpentan-2-one (1:3 v v ) with Malachite Green as counter-ion. A single extraction with equal phase volumes gives an apparent molar absorptivity for phosphate of 2.3 x 10(5) l.mole(-1).cm(-1) at 630 nm; the absorbance of the reagent blank is 0.03. With an organic to aqueous phase-volume ratio of 1:10, the molar absorptivity is 2.5 x 10(5) l.mole(-1).cm(-1) and the absorbance of the reagent blank 0.08. By the proposed method, ng ml levels of phosphorus can be determined, and the detection limit is about 0.1 ng ml . The standard deviation and relative standard deviation for the determination of phosphorus in tap water (4.3 ng ml ) are 0.05 ng ml and 1.1%, respectively. The method can also be applied to the determination of phosphorus in river water and sea-water.     

Screening and confirmation of triphenylmethane dyes and their leuco metabolites in trout muscle using HPLC-vis and ESP-LC-MS.

An extraction and clean-up protocol for the determination of Malachite Green and Crystal Violet and the corresponding leuco compounds in trout muscle has been developed. Final determination is by HPLC with visible (screening) or ESP-MS (confirmation) detection. In both cases lead(IV) oxide was used on-line to oxidise the leuco compounds back to the parent after chromatographic separation and prior to detection. The procedure was validated down to 2 micrograms kg-1. Intra- and inter-batch precision was measured at 3 levels for all compounds. Recoveries were in the range 66-116% with RSD of 1-17% for determination by HPLC with visible detection. For LC-MS determination, recoveries were in the range 61-94% with RSD of 4-15%. Limited surveillance data indicated that Malachite Green usage was more effectively monitored by including the leuco compound as well as the parent (9 positives for the leuco compound as opposed to 1 for Malachite Green out of 31 samples analysed).     

Indirect atomic-absorption determination of boron by solvent extraction as tris(1,10-phenanthroline)cadmium tetrafluoroborate

An indirect atomic-absorption method for boron has been developed. Boric acid is converted into tetrafluoroborate and extracted into nitrobenzene with Tris(1,10-phenanthroline)cadmium(II). The cadmium in the extract is determined by its atomic-absorption at 228s>d8 nm. A fivefold molar excess of the cadmium chelate is necessary for the extraction from pH 4>d3-6>d0 medium. The sensitivity for boron is thus made about the same as that of cadmium, 0>d005 ppm. Metal ions that react with fluoride or phenanthroline interfere. A procedure is described for determination of boron in steel.     

A novel and highly sensitive catalytic method with oscillopolarographic detection for the determination of ultratrace amounts of iridium

Iridium(IV) has a strong catalytic effect on the slow redox reaction between Malachite Green and periodate ion in pH 4.2 acetate buffer solution at 100 degrees , and Malachite Green exhibits a sensitive single-sweep oscillopolarographic wave at -0.65 V vs. SCE. This provides the basis for a novel and highly sensitive and selective catalytic method with oscillopolarographic detection for iridium. The effect of pH, potassium periodate and Malachite Green concentrations, reaction temperature and reaction time and other variables are investigated. The detection limit is 8 ng/l. with a fixed-reaction time of 10 min. A linear calibration graph from 24 to 1600 ng/l. is obtained. Possible interferences by co-existing ions are examined.     

Extraction-spectrophotometric determination of traces of antimony in copper and lead metals and in lead-base alloy with pyrocatechol violet and tri-n-octylamine

A sensitive spectrophotometric method is described for the determination of antimony in copper and lead metals and in lead-base alloy. Optimal conditions have been established for the extraction and determination of antimony. Antimony (III) is extracted from a potassium iodide—sulfuric acid or a hydrobromic—sulfuric acid medium with toluene and converted to an antimony-pyrocatechol violet (PV) complex. The complex is then extracted with tri-n-octylamine (TOA) and the absorbance of the resulting ternary Sb(III)—PV-TOA complex is measured at 555 nm. As little as 0.5 p.p.m. of antimony in copper metal and 0.2 p.p.m. of antimony in lead metal and lead-base alloy can be determined.     

Determination of silver, antimony, bismuth, copper, cadmium and indium in ores, concentrates and related materials by atomic-absorption spectrophotometry after methyl isobutyl ketone extraction as iodides

Methods for determining ~ 0.2 mug g or more of silver and cadmium, ~ 0.5 mug g or more of copper and ~ 5 mug g or more of antimony, bismuth and indium in ores, concentrates and related materials are described. After sample decomposition and recovery of antimony and bismuth retained by lead and calcium sulphates, by co-precipitation with hydrous ferric oxide at pH 6.20 +/- 0.05, iron(III) is reduced to iron(II) with ascorbic acid, and antimony, bismuth, copper, cadmium and indium are separated from the remaining matrix elements by a single methyl isobutyl ketone extraction of their iodides from ~2M sulphuric acid-0.1M potassium iodide. The extract is washed with a sulphuric acid-potassium iodide solution of the same composition to remove residual iron and co-extracted zinc, and the extracted elements are stripped from the extract with 20% v v nitric acid-20% v v hydrogen peroxide. Alternatively, after the removal of lead sulphate by filtration, silver, copper, cadmium and indium can be extracted under the same conditions and stripped with 40% v v nitric acid-25% v v hydrochloric acid. The strip solutions are treated with sulphuric and perchloric acids and ultimately evaporated to dry ness. The individual elements are determined in a 24% v v hydrochloric acid medium containing 1000 mug of potassium per ml by atomic-absorption spectrophotometry with an air-acetylene flame. Tin, arsenic and molybdenum are not co-extracted under the conditions above. Results obtained for silver, antimony, bismuth and indium in some Canadian certified reference materials by these methods are compared with those obtained earlier by previously published methods.     

火焰原子吸收法测定植物样品中硼与碘

将ＢＯ＾３－３转化为ＢＦ＾－４，ＩＯ＾－３转化为Ｉ＾－以Ｃｄ（ｐｈｅｎ）＾２＋３络合和硝基苯萃取，用火焰原子吸收法间接测定与碘，其特征浓度达０．０１６μｇ／ｍＬ１％Ａ和０．０２８μｇ／ｍＬ１％Ａ，在稻米等样品中作加标回收，硼回收率为９２．８－１０２．４％，碘为９７．２－１０６．７％。     

Microscopic location of photosensitive Malachite Green surfactant in mixed micelle and its photoinduced enhancement of solubilizing power

A Malachite Green derivative carrying a long alkyl chain affords photogenerated amphiphilicity by UV irradiation. The behavior of the photoresponsive Malachite Green surfactant was studied in mixed micelle solutions containing cetyltrimethylammonium chloride. We found that the Malachite Green surfactant increases the solubility of oily substance by UV irradiation. The role of the Malachite Green surfactant has been investigated by dynamic light scattering and spectroscopic analysis. The Malachite Green surfactant causes an increase in the micelle size, and its hydrophilic head group lies at the micellar interface. The mechanism of the photoinduced uptake of oily substances is discussed at the viewpoint of the microscopic location of the Malachite Green surfactant in the micelle.     

Photometrische Bestimmung kleiner Phosphatmengen mit Malachitgrün

In the presence of a stabilising colloid Malachite Green and phosphododekamolybdate acid form a dyestuff salt. When the excess of the Malachite Green has reacted in acid solution to colourless products, the remaining colour is a measure for the phosphate quantity. The method permits the determination of 10–1200 μg of phosphate/l.     

Determination of antimony in steel by hydride generation and by electrothermal zeeman atomic absorption spectrometry

Procedures are described for the determination of antimony in steel. Samples by decomposed with a nitric/perchloric acid mixture and antimony is determined either by a.a.s. after hydride generation with sodium tetrahydroborate or by graphite-furnace a.a.s. with Zeeman background correction. Some reference steel samples were analyzed by both methods and by instrumental neutron activation. The results obtained (45–680 μg g^?1 antimony) were in very good agreement; detection limits were about 3 μg g^?1. The relative standard deviation for samples with > 50 μg g^?1 antimony was 〈 5%.     

Determination of arsenic and antimony in electrolytic copper by anodic stripping voltammetry at a gold film electrode

A simple procedure is described for the determination of arsenic and antimony in electrolytic copper. The copper is digested with nitric acid and copper is separated from arsenic and antimony by passing an ammoniacal solution of the sample through a column of Chelex-100 resin. After digestion with sulphuric acid and reduction to arsenic(III) and antimony(III) with sodium sulphite in 7 M sulphuric acid at 80°C, both arsenic and antimony are deposited at-0.30V and their total is determined by anodic stripping; antimony is then selectively deposited at -0.05 V for anodic stripping. The lower limits of determination are 56 ng As and 28 ng Sb per gram of copper; relative standard deviations (n = 5) are in the ranges 6.1–15.0% for 5.5—0.5 ppm arsenic in copper and 4.1–6.8% for 2.6—0.6 ppm antimony.     

Membrane Potential Photoresponse of Crowned Malachite Green Derivatives Affording Perfect Photoswitching of Metal Ion Complexation

Photoirradiation effect on potential response to metal ion concentrations and photoinduced potential change were investigated with poly(vinyl chloride) membranes based on a Malachite Green derivative carrying a bis(monoaza-15-crown-5) moiety, by comparing other Malachite Green derivatives. The Malachite Green carrying a bis(crown ether) moiety caused a potential response to potassium ion concentration changes under dark condition. In the membrane potential response, a clear-cut photoinduced switching of potential response was realized by the membrane of Malachite Green carrying a bis(crown ether) moiety, which exhibited no potential response to potassium ion concentrations (0 mV/decade) on UV irradiation. On the other hand, a Malachite Green carrying a monocyclic benzocrown ether moiety showed a considerable dependence of the membrane potential on the metal ion concentrations under both dark and UV irradiation conditions.     

Membrane Potential Photoresponse of Crowned Malachite Green Derivatives Affording Perfect Photoswitching of Metal Ion Complexation

Photoirradiation effect on potential response to metal ion concentrations and photoinduced potential change were investigated with poly(vinyl chloride) membranes based on a Malachite Green derivative carrying a bis(monoaza-15-crown-5) moiety, by comparing other Malachite Green derivatives. The Malachite Green carrying a bis(crown ether) moiety caused a potential response to potassium ion concentration changes under dark condition. In the membrane potential response, a clear-cut photoinduced switching of potential response was realized by the membrane of Malachite Green carrying a bis(crown ether) moiety, which exhibited no potential response to potassium ion concentrations (0 mV/decade) on UV irradiation. On the other hand, a Malachite Green carrying a monocyclic benzocrown ether moiety showed a considerable dependence of the membrane potential on the metal ion concentrations under both dark and UV irradiation conditions.This revised version was published online in July 2005 with a corrected issue number.     

Extraction-spectrophotometric determination of germanium(IV) with mandelic acid and malachite green

A method has been developed for determination of germanium, based on complexation with mandelic acid and extraction of the ion-associate formed with Malachite Green (MG) into chlorobenzene. A weakly acidic aqueous solution (pH 2.5-3.5) at room temperature is used and indirect determination is achieved by measuring the absorbance of MG in the extract, at 628 mn. The calibration graph is linear over the range (0.17-8.63) x 10(-6) (0.05-2.50 mug of germanium); the apparent molar absorptivity is 1.33 x 10(5) 1.mole(-1).cm(-1). The interferences from Fe, Ti, Sn(IV), Mo, and SB(III) can be eliminated by addition of trans-1,2-diaminocyclohexanetetra-acetic acid and sodium diethyldithiocarbamate.     

Synthesis of thiazole derivatives

By condensing aldehydes of the benzothiazole series with dimethylaniline, leuco-bases of dyes of the type of Malachite Green have been synthesized. The oxidation of these bases has given new analogs of Malachite Green containing benzothiazole nuclei; the main absorption maxima of the dyes have been determined.For Communication XXIV, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1037–1039, August, 1973.