Spectrophotometric determination of germanium by phenylfluorone

Spectrophotometric studies on the reaction between germanium ions and phenylfluorone were discussed including the reaction condition to develop a spectrophotometric method for the determination of germanium. The absorbance was measured at 525 nm after 20 min from the moment of adding the reagent. Beer's Law is obeyed, the relative standard deviation is 2%, the senstivity of the method is 2.55 × 10⁻³ mg/cm³, and the molar absorbtivity based on germanium is 1.75 × 10³.     

Spectrophotometric determination of molybdenum with lobeline

Lobeline hydrochloride has been tested as a reagent for molybdenum(V). Molybdenum(VI) is reduced with hydrazine sulfate in hydrochloric acid solution to Mo(V) only and complexed with thiocyanate and lobeline which is extracted with chloroform. In the paper experimental conditions for the formation of the ion pair of lobeline with molybdenum thiocyanate are described and the composition of this complex is given.     

Spectrophotometric molybdenum determination with thiolactic acid

A quick, selective method for molybdenum(VI) is based on the formation of a yellow thiolactic acid complex. The complex is formed at pH 1.0-1.6, and the absorbance is measured at 365 nm.     

Spectrophotometric determination of molybdenum with 8-mercaptoquinoline

8-Mercaptoquinoline was found to be sensitive for the colorimetric determination of molybdenum. A procedure is outlined in which the complex formed, Mo(C₉H₆NS)₂, is extracted into chloroform and the extinction measured at 425 mμ. The effects and removal of interfering ions are discussed.     

Spectrophotometric determination of chromium(VI) through ion-pair formation with phenylfluorone

Two successive outer sphere complexes with mole ratios of 1:1 and 1:2 are formed between chromium(VI) and phenylfluorone at pH 1.5 in 40% ethanol. These have absorption maxima at 490 and 470 nm, respectively. The 1:1 complex obeys Beer's law at 500 nm (? = 2.1 × 10⁴ 1 mol^-1 cm^-1) in the range 13–1700 ng l^-1 chromium(VI).     

Spectrophotometric determination of iron as phenylfluorone complex sensitized with Triton X-100

Summary The effect of some surfactants and protective colloids on the absorbance of the iron(III)-phenylfluorone complex has been investigated. The binary complex formed at pH 9.0 show a molar absorptivity of 7.5×10⁴ l · mol^–1 · cm^–1 at 530 nm. In the presence of 2% Triton X-100, at the same pH, the molar absorptivity of the sensitized complex was 1.19×10⁵ l · mo^–1 · cm^–1 at 555 nm. Full colour development of the sensitized complex occurred within 25 min and Beer's law was followed up to 0.53 ppm of iron. The molar ratio and continuous variation methods indicated a 13 metal-ligand ratio for the sensitized complex. The effect of various amounts of different ions has been studied under the experimental conditions and some masking agents were recommended. The method has been applied to the determination of iron in copper and nickel metals and some non-ferrous alloys.

---

Spektralphotometrische Bestimmung von Eisen als Phenylfluoronkomplex sensibilisiert mit Triton X-100

     

Spectrophotometric determination of microquantities of molybdenum

Summary A new spectrophotometric method for the determination of microquantities of molybdenum (VI) and rutin, respectively, has been described. In order to take all the advantages of this very sensitive method, the effect of some foreign ions on these determinations has been studied and a combined chromatographic-spectrophotometric procedure for the separation and the determination of microamounts of molybdenum (VI) in the presence of a large number of interfering ions has been developed.

---

Spektrophotometrische Bestimmung von Mikromengen Molybdän

Zusammenfassung Eine neue spektralphotometrische Methode zur Bestimmung von Mikromengen von Molybdän(VI) bzw. von Rutin wurde beschrieben und der Einfluß einiger Fremdionen auf diese Bestimmung untersucht. Um die Anwendungsmöglichkeiten dieser Methode zu erweitern, wurde ein kombiniertes chromatographisch-spektrophotometrisches Verfahren zur Abtrennung und Bestimmung von Mikromengen Molybdän(VI) in Gegenwart einer größeren Zahl störender Ionen ausgearbeitet.

     

Spectrophotometric determination of molybdenum in rocks with thiocyanate

A rapid procedure for the determination of microgram amounts of molybdenum in rocks is described. After acid decomposition, molybdenum is extracted from a hydrochloric acid solution into xylene with tributyl phosphate. After back-extraction with water, molybdenum is extracted as the α-benzoinoximate into chloroform, stripped into hydrochloric acid extracted as the thiocyanate into amyl alcohol, and determined spectrophotometrically. The molybdenum thiocyanate color produced is stable, sensitive, and reproducible. Results of analyses of several of the U.S. Geological Survey standard rocks are given.     

Spectrophotometric determination of germanium based on its ternary complex with phenylfluorone and zephiramine

A sensitive Spectrophotometric method for the determination of germanium based on its ternary complex with phenylfluorone and zephiramine was developed. The complex forms in 0.3–1.5 M HCl medium. Maximum absorbance is obtained for the molar ratio of Ge:PF:zeph = 1:16:600. Molar absorptivity (ϵ) is 1.38 × 10⁵ liters mol⁻¹ cm⁻¹ at λ_max = 505 nm. Due to the limited selectivity of the method (Sn, Sb, Nb, Ta, Ti, V, Mo, ClO₄⁻, SO₄²⁻, PO₄³⁻) before determining trace amounts of germanium, it should be separated, e.g., by extraction. Germanium in galman ore was determined with the developed method (about 1 × 10⁻³%). Attempts to achieve satisfactory analytical results failed in the presence of cetyltrimethylammonium ions or cetylpyridinium ions used as cationic surfactants.     

Spectrophotometric and volumetric molybdenum determination with 2,2'-biquinoxalyl

Volumetric and spectrophotometric methods for molybdenum determination based on reaction with 2,2'-biquinoxalyl (2,2'-BQx) in concentrated hydrochloric acid media have been developed. Absorption spectra of the 1,1'-dihydro 2,2'-biquinoxalylene complex shows the most intensive absorption band at 685 nm with molar absorptivity = 3.3 x 10(4) 1. mole(-1). cm(-1). The compound is characterized by good durability to high temperatures and concentrated acid media. The mentioned indicator gives distinct colour changes at the titration end-point. The spectrophotometric method for molybdenum determination is based on the use of the difference in absorbance between the oxidized and reduced forms of 2,2'-BQx. The indicator is reduced with Sn(II) and then part of it is reoxided as a result of addition of Mo(VI). The difference in absorbance between the blank determination and molybdenum sample increases linearily in the concentration range 0.2-2.0 mug Mo/cm(3). 2,2'-Biquinoxalyl was used as an indicator in the volumetric method for the determination of molybdenum concentrations in steel alloy. The interfering ions FE(III) and Cr(III) are easily eliminated as the precipitate of hydroxides. The mineral acids, hydrochloric sulphuric and perchloric acids, have been tested as reaction media.     

Spectrophotometric determination of molybdenum(vi) with benzoylacetanilide

Abstract

The complex formed between molybdenum(VI) and benzoylacetanilide in the pH range 0.6 and 1.9 has been extracted into methyl isobutyl ketone and the absorbance has been measured at 410 mμ. Quantities of 0.15 to 2.10 mg of molybdenum have been determined with a standard deviation of 0.6%. The color is stable up to 2 hours. The presence of Co²⁺, Ni²⁺, Zn²⁺, Mn²⁺, Be²⁺, Al³⁺, Cr³⁺, Ce⁴⁺, Th⁴⁺ or UO²⁺ ₂ up to 100 μg causes no interference. Ordinarily, Fe³⁺ interferes with the determination, but when masked with 1 ml of 0.5% solution of ascorbic acid the tolerance limit is 10 mg. Thus, molybdenum can be determined in steel when present in amounts as low as 0.26%.     

Spectrophotometric determination of molybdenum(VI)

Molybdenum(IV) gives a red colour with ammonium thiocyanate in 5-8M hydrochloric acid medium, the Sandell sensitivity index being 0.018 ppm Mo(VI)/cm(2). Molybdenum(VI) in 4-7M hydrochloric acid medium forms a red complex with ethyl xanthate and ammonium thiocyanate and this can be extracted into acetophenone. Beer's law is obeyed over the range of 1.2-13.8 ppm, and the Sandell indices at 370 and 470 nm are 0.0016 and 0.0068 ppm/cm(2) respectively. The colour is stable for 40 hr. Most cations do not interfere.     

Spectrophotometric determination of palladium(II) with phenylfluorone in the presence of hexadecylpyridinium bromide

Phenylfluorone reacts with palladium(II) in the presence of hexadecylpyridinium bromide to form a water-soluble chelate with an absorption maximum at 630 nm, the absorbance being constant in the pH-range of 9.0–10.2. At this wavelength Beer's law is obeyed up to 7.25 × 10^–5 mol/L palladium(II). The sensitivity is very high and the molar absorptivity is 8.5 × 10⁴ L mol^–1 cm^–1, permitting the determination of palladium(II) at µg level. The ratio of palladium to phenylfluorone in the complex is 1:1. The method has successfully been applied to the determination of palladium in titanium alloys.     

2,3,7-三羟基-9-(3,4-二羟基)苯基荧光酮光度法测定锌

研究了新型苯基荧光酮类显色试剂2,3,7-三羟基-9-(3,4-二羟基)苯基荧光酮(3,4-DHPF)与锌离子显色反应的条件及应用. 结果表明, 在阳离子表面活性剂溴化十六烷基三甲胺(CTMAB)存在下, 在pH 8.2的Na2HPO4-KH2PO4缓冲溶液中, 锌与3,4-DHPF形成1∶1的红色络合物, 所形成的络合物的最大吸收值位于560 nm处, 表观摩尔吸光系数为1.23×105 L·mol-1·cm-1;红色络合物至少稳定8 h以上, 锌含量在0～1.40 μg/5 mL范围内符合比尔定律;拟定方法已用于茶叶中微量锌的测定.     

Spectrophotometric determination of molybdenum and tungsten in niobium with dithiol

A new procedure for the determination of molybdenum and tungsten in niobium has been developed. The method involves the formation of the intensely colored complex of molybdenum with toluene-3,4-dithiol in an aqueous medium and its extraction into carbon tetrachloride followed by the reduction of tungsten and the formation and extraction of its complex. The recommended reagent is stable for at least 90 days. Both the molybdenum and the tungsten dithiol complexes are formed quantitatively within 5 min. Interlaboratory evaluation of the method reveals within-laboratory and between-laboratory relative standard deviations of about 1.5% and 2.9% respectively.     

Test determination of molybdenum(VI) with the use of phenylfluorone immobilized on a cellulose cloth

It was demonstrated that phenylfluorone immobilized on a cellulose cloth matrix can be used as a reagent for the test determination of molybdenum(VI). Phenylfluorone was immobilized on a mixed fiber cloth (viscose with cotton), which provides high retention of the reagent (97%) and exhibits chemical stability and mechanical strength. The selectivity of the reaction was studied. A test procedure was developed for the determination of 0.05–5 mg/L molybdenum(VI) in natural waters (RSD < 40%); the time of analysis is 10–15 min.     

Spectrophotometric determination of molybdenum in steels with o-nitrophenylfluorone and cetyltrimethylammonium bromide

A method has been developed for determining microamounts of molybdenum(VI) in aqueous solution by means of the Mo-o-nitrophenylfluorone—cetyltrimethylammonium bromide system, in which micellar solubilization is applied. A red complex is formed in 0.2–0.6M hydrochloric acid medium. The sensitivity of the method is high, and the apparent molar absorptivity is 1.55 × 10⁵ l.mole⁻¹. cm⁻¹. The absorption peak of the complex appears at 530 nm. The colour of the complex develops quickly and is stable for more than 24 hr. The composition of the complex is Mo: o-NPF = 1:1, and the system obeys Beer's law in the range 0–10 μg of Mo per 25 ml. The method has been used for the rapid determination of molybdenum in alloy steels with satisfactory results.     

Spectrophotometric determination of molybdenum with 9-methyl-2,3,7-trihydroxy-6-fluorone

9-Methyl-2,3,7-trihydroxy-6-fluorone is proposed as a highly sensitive reagent for molybdenum. Thc rose-red complex shows maximum absorption at 510 mμ and obeys Beer's law from 0.2 to 3 p.p.m. of molybdenum, the optimum range being 08 to 3 p p m. where the percent relative analysis error is only 28. In solution the complex contains molybdenum and the reagent in the ratio 1:1. The instability constant of the complex is about 2.09·10^-6.