Titan Yellow

Two methods are commonly used for the determination of magnesium. Titan yellow may be used to obtain a coloured colloidal suspension, or solochrome black to give a red soluble complex. In most cases the second of these is to be preferred. 

Titanium, D. of as oxide, via tannic acid and phenazone complexes, (g) 470 by hydrogen peroxide, (s) 696 Titan yellow 692 Titrand 257 Titrant 257 Titration 257 classification of, 258 in an inert atmosphere, 376, 629 in non-aqueous solvents, 281 aniline (and ethanolamine), D. of, 307 indicators for, 283 solvents for, 283... 

Chrome Niobium Titanate Yellow, pigment for plastics, 7 370t Chrome Orange, 6 523, 554, 555t pigment for plastics, 7 370t Chrome ore, as a refractory raw material, 21 490... 

Nickel niobium, 17 123—124 Nickel Niobium Titanate Yellow, pigment for plastics, 7 370t... 

Important twentieth-century developments include the addition of Molybdate Red to the series of inorganic synthetic coloring matters in 1936 Titan Yellow followed in 1960. 

Magnesium (as MgO) Place 400.0 mg of sample, 5 mL of 2.7 A hydrochloric acid, and about 10 mL of water in a small beaker, and dissolve the sample by heating on a hot plate. Evaporate the solution to a volume of about 2 mL, and cool. Transfer the residual liquid into a 100-mL volumetric flask, dilute to volume with water, and mix. Dilute 7.5 mL of this solution to 20 mL with water, add 2 mL of 1 A sodium hydroxide and 0.05 mL of a 1 1000 solution of Titan yellow (Clayton yellow), mix, allow to stand for 10 min, and shake. 

Titan yellow reagent titan yellow (also known as clayton yellow) is a water-soluble yellow dyestuff. It is adsorbed by magnesium hydroxide producing a deep-red colour or precipitate. Barium and calcium do not react but intensify the red colour. All elements of Groups I to III should be removed before applying the test. 

The reagent consists of a 0T per cent aqueous solution of titan yellow. 

Titan yellow (0-1 %). Dissolve 0-1 g Titan yellow (Clayton yellow, Colour Index 19540) in 100 ml water. 

Colorimetric methods The determination of magnesium is carried out by complexation with coloring agents such as eriochrome black T [23], titan yellow [24], 5,7-diiodo-8-quinolinol and rhodamine S [25], beryllon II [26], quinolin-8-olate [27,28] leucoquinizarin [29], emodin [30,31], pur-purin [32], or bromopyrogallol red [33]. 

In the virtually ignored study by Dai (with three nonself citations in five years) [521], the paper by Graham [451] is not cited either, but the key issue is both identified and clarified. Based on the results summarized in Fig. 21, the author concluded that electrostatic interaction between cationic dyes and the surface of activated carbon has a great effect on adsorption capacity. Below the isoelectric point of the activated carbon (when the positive zeta potential was above 60 mV), the capacity is significantly reduced due to electrostatic repulsion between cationic dyes and the carbon surface. In a follow-up study, while still failing to acknowledge earlier important contributions to the resolution of the key issues, Dai [522] reinforced and confirmed the electrostatic attraction vs. repulsion arguments. The author used anionic dyes (phenol red, carmine, and titan yellow) and... 

Titan yellow is also the best visualizing reagent for detection of m-cresol on silica gel 60 F254 (detectability 1.08 pg). ... 

Figure 1 represents four examples of the evaluation of measurement uncertainty for potassium, calcium, magnesium and glucose using flame photometry, atomic absorption spectrometry and molecular spectrometry (Mg determination with Titan Yellow and glucose determination with glucose oxidase). For the sake of simplicity in Fig. 1, the component of uncertain-... 

It should be noted that when we used methods of measurement needing inorganic reference materials for calibration (such as flame photometry or atomic absorption spectrometry) the uncertainty due to the reference materials was considerably lower than that due to the photometric device. On the contrary, when we used a clinical reference material certified for its glucose concentration with a 10% (rel) uncertainty, this uncertainty exceeded twice the uncertainty due to the spec-trophotometric device. When we determined Mg by a spectrophotometric method with Titan Yellow, we found that the uncertainty due to the reference material was approximately twice that due the device, as we used a very accurate spectrophotometer. 

The coloured adsorption compounds formed by Mg(OH)2 with organic dyes are essential parts of the methods for determining magnesium (e.g., the Titan Yellow method). Other methods are based on soluble coloured magnesium complexes formed with some organic reagents (e.g., Eriochrome Black T) in ammoniacal media. 

The molar absorptivity of the pseudo-solution of the magnesium compound with Titan Yellow is 3.6-10 at 545 (a = 1.5). The intensity and reproducibility of the colour obtained are affected by the method of pH adjustment, the excess of Titan Yellow, the protective colloid used, the temperature of the solution, and the time of standing. Immediately after the start of the colour reaction, an increase in absorbance is noticed, but after 10-30 min the colour of the solution remains almost constant. After this it weakens progressively. Hydroxylamine is reported to stabilize the colour [12]. 

A synergistic effect on the determination of magnesium is exerted by calcium. Although calcium itself gives no colour reaction with Titan Yellow, its presence with the magnesium causes increased absorbance. Since no further increase occurs above a certain concentration of calcium, the increased absorbance is exploited by adding excess of calcium to the sample and the standard solutions. 

Species which decrease the quantity of Mg(OH)2 precipitated upon the addition of NaOH, sueh as ammonium salts, and anions which precipitate Mg (e.g., phosphate), interfere in the Titan Yellow method. A number of metal cations decrease or increase the colour intensity. Decreased absorbance in the presence of Al, Zn, or Sn(IV) is believed result from adsorption of aluminate, zincate or stannate ions on the Mg(OH)2, which reduces the amount of dye adsorbed. 

Titan Yellow, 0.01% solution. Dissolve 10 mg of the reagent in 100 ml of water. The solution is stable for at least one week. 

To the sample solution, in a 25-ml standard flask, containing not more than 12 pg of Mg, add 1 ml of the calcium chloride solution, 2.5 ml of the Titan Yellow solution, 3 ml of 1% polyfvinyl alcohol) solution, and water to 17 ml. While swirling the solution vigorously, add 1 M NaOH dropwise from a burette until the solution changes colour. Then add 2.5 ml more NaOH solution with continued mixing, and dilute the solution with water to the mark. After 15 min, measure the absorbance of the solution at 545 nm against a blank solution containing the same amount of calcium. 

Besides Titan Yellow, several other organic dyes have been recommended which react with Mg(OH)2 to form adsorption compounds in alkaline media, e.g., Magneson II, Phenazo [11], and polymethine dyes [19-21]. 

Titan Yellow has been used for determination of magnesium in nickel and its alloys [3], silicate minerals [14,58], carbonate minerals [58], soil extracts [13], plant materials [59], and blood [60]. 

Hydroxyquinoline 8-Hydroxy quinoline + Butylamine Titan Yellow... 

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