Platinum chloride analysis

But [said he] it was still necessary to learn the base of the salt. Its solution could not be precipitated either by tartaric acid in excess or by platinum chloride. Consequently it could not be potassium. I mixed another portion of a solution of the same salt with a few drops of pure potash, but without its becoming cloudy. Therefore it contained no more magnesia hence it must be a salt with soda for a base. I calculated the quantity of soda which would be necessary to form it but it always resulted in an excess of about 5 parts in 100 of the mineral analyzed. Therefore, since it seemed probable to me that the different substances might not have been well washed, Or that the analysis might not have been made with sufficient precision in other respects, I repeated it twice more with all the care possible, but always with results very little different. I obtained. Silica. 78 45, 79.85, Alumina 17 20, 17.30 Sulfate 19.50, 17.75. At last, having studied this sulfate more closely, I soon found that it contained a definite fixed alkali, whose nature had not previously been known (21). 

Color. Many water samples have a yellow to brownish-yeUow color which is caused by natural substances, eg, leaves, bark, humus, and peat material. Turbidity in a sample can make the measurement of color uncertain and is usually removed by centrifiigation prior to analysis. The color is usually measured by comparison of the sample with known concentrations of colored solutions. A platinum—cobalt solution is used as the standard, and the unit of color is that produced by 1 mg/L platinum as chloroplatinate ion. The standard is prepared from potassium chloroplatinate (K PtCl ) and cobalt chloride (C0CI26H2O). The sample may also be compared to suitably caUbrated special glass color disks. 

Induced dissolution is also a well known phenomenon and frequently applied in chemical analysis. To dissolve platinum easily it was suggested by Ropp that the sample should be alloyed with silver or copper, the alloys being easily soluble even in dilute acids. Anhydrous chromic chloride, insoluble in water and dilute acids, becomes easily soluble by adding metallic magnesium or zinc to the dilute acid . In this case the chromium(III) compound is reduced to chro-mium(II), which will be oxidized by the solvent to water-soluble chromium(III)... 

Figure 17.6 (a) Reverse normal pulse voltammogram, (b) current measured prior to the analysis pulse in (a), and (c) normal large-amplitude pulse voltammogram at a platinum electrode for a 13.4 mM solution of Ti(IV) in the 60-40 mol% AlCl3-l-methyl-3-ethylimidazolium chloride melt at 25°C. [From Ref. 68, with permission.]... 

Platinous compounds [see specific compounds under Platinum (II)] Platinum (II) chloride, 5 208 6 209 analysis of, 5 209 Platinum (IV) chloride, 2 253 Platinum (II) complex compounds, anions, with 1,4-butadiene, K2[Cl3PtC4H6PtCI3], 6 216 anions, with ethylene, [Pt(C2H4)-CU]K, 5 211, 214... 

A Pt(II)-bridged wire compound was prepared by Mayor et al. [18] by treating trans-bis(triphenylphosphane)platinum(II) chloride (63) with the alkyne 4 and Cul as catalyst (Scheme 10.20). The trans configuration of the product 64 was confirmed by X-ray crystallographic analysis. 

Bjerkandera adusta 50 A platinum disk was used as working electrode. The reference electrode was a silver-silver chloride electrode. Analysis at pH 7.0 [44]... 

Phillips and Timms [599] described a less general method. They converted germanium and silicon in alloys into hydrides and further into chlorides by contact with gold trichloride. They performed GC on a column packed with 13% of silicone 702 on Celite with the use of a gas-density balance for detection. Juvet and Fischer [600] developed a special reactor coupled directly to the chromatographic column, in which they fluorinated metals in alloys, carbides, oxides, sulphides and salts. In these samples, they determined quantitatively uranium, sulphur, selenium, technetium, tungsten, molybdenum, rhenium, silicon, boron, osmium, vanadium, iridium and platinum as fluorides. They performed the analysis on a PTFE column packed with 15% of Kel-F oil No. 10 on Chromosorb T. Prior to analysis the column was conditioned with fluorine and chlorine trifluoride in order to remove moisture and reactive organic compounds. The thermal conductivity detector was equipped with nickel-coated filaments resistant to corrosion with metal fluorides. Fig. 5.34 illustrates the analysis of tungsten, rhenium and osmium fluorides by this method. 

In a second method of analysis employed with this salt the weighed mixture of osmium and potassium chloride, obtained as before, was ignited in a boat in a platinum tube until the potassium chloride had volatilised, a current of hydrogen passing through the tube during the experiment. The residual osmium was then weighed ... 

Sulphur alone has no action upon platinum,3 but metallic sulphides are liable to attack it. Phosphorus, phosphides, and phosphates under reducing conditions attack the metal, so that these and the aforesaid sulpirides should not be ignited in platinum crucibles in quantitative analysis. Ferric chloride solution is reduced to ferrous chloride when evaporated in a platinum dish, platinum passing into solution. 

Exact Value.—The first determination of the atomic weight of platinum was made by Berzelius in 1826.3 From the analysis of platinous chloride he found Pt = 194-7. Two years later he published his determination of the composition of potassium chlor-platinate4 6-981 parts of the salt lost 2-024 of chlorine when ignited in hydrogen, leaving a residue containing 2-822 of platinum and 2-135 of potassium chloride. Hence ... 

The metallointercalation reagents are a class of heavy metal derivatives that bind to double-stranded polynucleotides by inserting between adjacent base pairs in the helix.1 2 Prototype members of this class of intercalators are (2,2 6, 2"-terpyridine)(thiolato)platinum(II) complexes.3 These may be synthesized from chloro(2,2 6, 2"- terpyridine)platinum(II), which can both intercalate and bind covalently by losing chloride ion. Covalent binding of the thiolato complexes is much slower owing to the more inert character of the Pt—S bond. Metallointercalation reagents also have the potential to bind to proteins that have natural receptor sites for nucleic acid bases. They may therefore also be used to provide isomorphous heavy atom derivatives for X-ray analysis. 

Analysis of the compound for platinum is accomplished gravimetrically by reduction of a known weight of the anhydrous salt to metallic platinum with formic acid.3 For the determination of chloride, 0.3 g. of the anhydrous salt is dissolved in 40 ml. of distilled water containing 250 mg. of hydrazine sulfate the solution is boiled gently until platinum metal is formed and coagulated. Then, without removal of the platinum, the solution is made 1 f in nitric acid and is titrated potentiometrically with standard 0.2 F silver nitrate solution. Anal. Calcd. for Na2PtCl6 Pt, 42.99 Cl, 46.88. Found Pt, 42.78 Cl, 46.73. 

In quantitative analysis sodium is estimated as sulphate, formed by evaporation with concentrated sulphuric acid. If potassium be present, its amount is determined by precipitation as double chloride with platinum from the solution of the mixed sulphates.1... 

Vinyltrimethylsilane (97%), trimethylchlorosilane (98%), chlorodimethylsilane (97%), bromoform (96%), 5-bromo-l-pentene (95%), nBuLi (2.5M solution in hexanes), MeLi (1.6M solution in diethyl ether), n-decane (puriss. p.a., standard for GC, > 99.8%) and hexachloroplatinic(lV) acid hydrate were purchased from Aldrich. Platinum divinyltetramethyldisiloxane complex (Karstedt s catalyst, 3% solution in xylenes), hexamethyl-cyclotrisiloxane (95%), vinylmethyldichlorosilane (97%) and 1,1,3,3-tetramethyldisiloxane (97%) were bought from ABCR. Bromine (puriss) was bought from Eluka. Triethylamine (pure for analysis) and zinc oxide (pure) was purchased from Chempur. Solvents (tetrahydrofurane, diethyl ether, methylene chloride, pentane, ethyl acetate) were supplied by POCh (Polish Chemical Reagents). 

Wollaston s First Process. Aqua regia consisting of 2.7 mL hydrochloric acid (25%), 0.3 mL nitric acid (70%), and 1.7 mL water was added to 0.99 g crude platinum, and the mixture, in a 10-mL round-bottomed flask, was heated at 55 °C in a sand bath for 3 days. The undissolved residue (299 mg) was then filtered off, washed, dried, and 33 mg was separated for analysis. A 1-mL aliquot of the aqua regia solution was evaporated to dryness to yield 83 mg of residue, which was analyzed. Ammonium chloride solution (3.7 M) was added dropwise to the remaining aqua regia solution until precipitation ceased (2.0 mL added). 

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