Ammonium photometric determination

The method of extraction of Ru(III) from thiocyanate solutions by water soluble extractants in the presence of ammonium sulfate as salting out agent followed by photometric determination of it in extract has been elaborated. 

Ganescu et al. used a thiocyanto-Cr(III)-complex for the spectro-photometric determination of dipyridamole (1-15 mg) in 25 mL of solution [16]. The solution was acidified with 1-2 mL of 1 M hydrochloric acid, and treated with a slight excess of ammonium diimidazoletetrakis (thiocyanato) chromium (III). The precipitate was collected and washed, dissolved in acetone, and diluted to 25 mL with the same solvent. The absorbance was measured at 540 nm (molar absorptivity equal to 846). 

Dissolved monomer determination Photometric determination of silicomolybdic acid with ammonium molybdate according to Motomizu... 

C. W. Ballard, J. Isaacs, and P. G. W. Scott, The Photometric Determination of Quaternary Ammonium Salts and of Certain Amines by Compound Formation with Indicators, J. Pharm. Pharmac. 6, 971 (1954). 

Methanol can be converted to a dye after oxidation to formaldehyde and subsequent reaction with chromatropic acid [148-25-4]. The dye formed can be deterruined photometrically. However, gc methods are more convenient. Ammonium formate [540-69-2] is converted thermally to formic acid and ammonia. The latter is trapped by formaldehyde, which makes it possible to titrate the residual acid by conventional methods. The water content can be determined by standard Kad Eischer titration. In order to determine iron, it has to be reduced to the iron(II) form and converted to its bipyridyl complex. This compound is red and can be determined photometrically. Contamination with iron and impurities with polymeric hydrocyanic acid are mainly responsible for the color number of the merchandized formamide (<20 APHA). Hydrocyanic acid is detected by converting it to a blue dye that is analyzed and deterruined photometrically. 

The total cerium content in the single crystal samples on the basis of rare-earth elements is determined by photometry after Ce(III) oxidation by ammonium persulfate. The Ce(III) content is calculated from the difference. Comparison of the determination results of the total cerium content obtained by photometric and atomic emission methods for Li GdlBO ljiCe demonstrated the elaborated procedure precision and systematic error absence. 

There also exists interference from diphosphoric acid, other more highly condensed phosphoric acids, and their organic derivatives. The free phosphoric acid can be determined as a heteropolyacid complex of phosphoric acid and ammonium molybdate. Afterward the complex is reduced by stannum II chloride to molybdenum blue. The amount of this dye can be measured photometricly at 625 nm. Organic derivatives of phosphoric acid and condensed phosphoric acids do not interfere with this method. 

The Oxamyl in this extract is then determined by gas chromatography using on-column reaction with trimethylphenyl ammonium hydroxide, the derivative so formed being determined by a flame photometric detector operated in the sulphur mode. Both Oxamyl and Oxamyl oxime in the soil react with trimethylphenyl ammonium hydroxide to form the same methoxime derivative (CH3)2NCOC(SCH3) -NOCH3. 

The analytes typically determined by using this type of sensor are those usually addressed by gas-diffiision systems, viz. ammonia (or ammonium ion), carbon dioxide (or carbonates) and oxygen. The detection system used is most frequently photometric, fluorimetric or potentiometric, and can be integrated with or connected to the sensing microzone. The description below is based on the two choices shown in Fig. 5.4. 

A post-column derivatization with subsequent photometric detection has also been developed for the determination of aluminium. Using a mixture of ammonium sulfate and sulfuric acid, aluminium is separated as A1S04+ ion on a cation exchanger. It forms a stable complex with the disodium salt of 4,5-dihydroxy-l,3-benzenedisulfonic acid (Tiron) at pH 6.2 which can be detected at 313 nm. 

Indirect photometric detection was also utilized for cation determination. Fig. 6-19 illustrates the separation of sodium, ammonium, and potassium with copper sulfate as the eluent obtained by Small et al. [29]. Aromatic bases as cationic analogues to aromatic acids used in anion analysis are inappropriate as eluents for this detection method. As monovalent cations, they are already eluted by the oxonium ions. Thus, a significant absorption change is only observed when the protonated base cation contributes to the ion-exchange process. 

The most important forms of phosphorus are inorganic orthophosphates which are determined photometrically with molybdenum. Orthophosphates react with ammonium molybdate in the presence of sulphuric acid and antimony ions to form heteropolyacids — phosphomolybdic acid. By reduction with ascorbic acid the yellow complex of phosphomolybdic acid changes into a solution of Phosphomolybdic Blue which can be determined photometrically ... 

The total aluminium in the solution may be determined by a photometric method with aluminon (ammonium salt of 4-hydroxy-5,5 -dimethylfuchso-ne-3,3 -dicarboxylic-2 -sulphonic acid), by a gravimetric method, by atomic absorption spectrometry. X-ray fluorescence, etc. 

The ammonium ions are now determined either acidimetrically or photometrically in aliquot parts (see Ammonium, Section 3.3.5). 

The nitrogen contained in organic substances in water is converted to ammonium ions by KjeldahEs decomposition method. The ammonium ions are distilled from alkaline solution as ammonia, collected in boric acid solution and determined acidimetrically or photometrically in the receiver. Ammonium ions originally contained in the sample are separated, identified and deducted, or separated off by distillation before carrying out the Kjeldahl decomposition. Nitrite and nitrate are volatilized by H2SO4 in the... 

Reagents for acidimetric titration or photometric analysis of the ammonium-ion content in the distillate see "Acidimetric determination following... 

Phosphate is mostly determined photometrically through the reaction with ammonium heptamolyb-date in acidic medium in the presence of potassium antimonyl tartrate as a catalyst. 12-Molybdophos-phoric acid is formed that upon reduction with, for example, ascorbic acid has a blue color. The lower limit of detection is lOpgl. Chromium(VI), nitrite, and high concentrations of chloride and iron interfere. The lower recoveries caused by iron are eliminated by addition of hydrogensulfite. 

The determination of molybdenum in soils and biological material used to be carried out mainly colorimetrically with rhodanide/isoamyl alcohol 8-hydroxyquinoline/CHCl3 methylisoamyIke-tone ammonium-pyrrolidine-dithiocarbamate/methylamylketone and with toluol-3.4-dithiol and different extracting agents (toluol, CHCI3, CCI4, n-butylacetate) [46]. The photometric methods must often be connected with accumulation procedures. 

A sensitive method for the determination of thiosulfate, thiocyanate and poly-thionates in a mixture with photometric detection at 230 nm illustrates further the applicability of ion-pair chromatography [9]. Excellent resolution of a complex mixture was obtained on a C18 column with a mobile phase of 6 mM tetrapropyl-ammonium acetate pH, 5.0, in 20-80% methanol-water (Figure 9.3). 

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