Emission spectrophotometry

Potassium is analyzed in chemicals that are used in the fertilizer industry and in finished fertilizers by flame photometric methods (44) or volumetric sodium tertraphenylboron methods (45) as approved by the AO AC. Gravimetric deterrnination of potassium as K2PtClg, known as the Lindo-Gladding method (46), and the wet-digestion deterrnination of potassium (47) have been declared surplus methods by the AO AC. Other methods used for control purposes and special analyses include atomic absorption spectrophotometry, inductively coupled plasma (icp) emission spectrophotometry, and a radiometric method based on measuring the radioactivity of the minute amount of the isotope present in all potassium compounds (48). 

Phosphorus and Silicon in Waters, Effluents and Sludges [e.g. Phosphorus in Waters, Effluents and Sludges by Spectrophotometry-phosphomolybdenum blue method. Phosphorus in Waters and Acidic Digests by Spectrophotometry-phosphovanadomolybdate method. Ion Chromatographic Methods for the Determination of Phosphorus Compound, Pretreatment Methods for Phosphorus Determinations, Determination of silicon by Spectrophotometric Determination of Molybdate Reactive Silicon-1 -amino-2-naphthol-4, sulphonic acid (ANSA) or Metol reduction methods or ascorbic acid reduction method. Pretreatment Methods to Convert Other Eorms of Silicon to Soluble Molybdate Reactive Silicon, Determination of Phosphorus and Silicon Emission Spectrophotometry], 1992... 

Table 25.1 Assay of Pharmaceutical Substances by Flame Emission Spectrophotometry (or FES) ...

ICP Inductively coupled plasma emission spectrophotometry IP image plate... 

The metal may he analyzed hy atomic absorption or emission spectrophotometry (at trace levels). Other techniques include X-ray diffraction, neutron activation analysis, and various colorimetric methods. Aluminum digested with nitric acid reacts with pyrocatechol violet or Eriochrome cyanide R dye to form a colored complex, the absorbance of which may be measured by a spectrophotometer at 535 nm. 

Elemental composition A1 52.91%, 0 47.08%. A1 may be anlayzed by atomic absorption or emission spectrophotometry or by colorimetric methods after acid digestion. Different forms of alumina may be identified by x-ray diffraction analysis. The X-ray crystallogaphic data for the mineral corundum are as follows ... 

Elemental analysis A1 15.77% O 56.12% S 28.11%. A1 may he determined hy colorimetric method or hy atomic absorption or emission spectrophotometry sulfate may he determined by BaCb precipitation method in the aqueous solution of the salt. 

Elemental composition H 4.11%, Mo 48.94%, N 14.29% O 32.65. (NH4)2Mo04 is digested with nitric acid and the molybdenum metal is analyzed by atomic absorption or emission spectrophotometry. It is dissociated to ammonia, which may be measured by titration or by an ion-specific electrode technique (see Ammonia). Ammonium molybdate reacts under acid conditions with dilute orthophosphate solution to form molybdophosphoric acid which, in the presence of vanadium, forms yellow vanadomolybdophosphoric acid the intensity of the yeUow color may be measured by a spectrophotometer at 400 to 490 nm and is proportional to the trace amount of ammonium molybdate. 

Tbe metal may most conveniently be analyzed in tbe aqueous phase by atomic absorption spectrophotometry using flame or a graphite furnace or by ICP emission spectrophotometry at wavelength 206.83 or 217.58 nm. Such measurements are accurate at trace concentration levels. The metal or its ore is digested with hot nitric acid and the acid extract is appropriately diluted and measured. 

The compound is cautiously dissolved in nitric acid and the solution is appropriately diluted for the analysis of antimony by AA spectrophotometry or ICP emission spectrophotometry and fluoride ion is determined by ion—selective electrode or ion chromatography. 

Elemental composition As 96.12%, H 3.88%. Arsine may be absorbed in potassium permanganate solution or in bromine water and the solution may be analyzed for arsenic by atomic absorption or emission spectrophotometry (see Arsenic). Alternatively arsine may be oxidized by moist air in presence of hght to arsenic which may then be digested with nitric acid and determined as above. 

Elemental composition Ba 58.89%, Ti 20.53%, O 20.58%. The sobd is digested with a mixture of concentrated H2SO4 and HNO3, diluted and the aqueous solution is analyzed for the metals Ba and Ti by flame or furnace atomic absorption or ICP emission spectrophotometry. The compound in the crystalline powdered form may be identified by various x-ray techniques. 

Boron may be analyzed by various instrumental methods, such as atomic absorption (AA) and atomic emission spectrophotometry (ICP/AES). Individual isotopes at an exceedingly trace concentration in solution phase may be measured by ICP/MS. The later method should be preferred over the AA techniques. 

Cadmium in acidified aqueous solution may be analyzed at trace levels by various instrumental techniques such as flame and furnace atomic absorption, and ICP emission spectrophotometry. Cadmium in solid matrices is extracted into aqueous phase by digestion with nitric acid prior to analysis. A much lower detection level may be obtained by ICP-mass spectrometry. Other instrumental techniques to analyze this metal include neutron activation analysis and anodic stripping voltammetry. Cadmium also may be measured in aqueous matrices by colorimetry. Cadmium ions react with dithizone to form a pink-red color that can be extracted with chloroform. The absorbance of the solution is measured by a spectrophotometer and the concentration is determined from a standard calibration curve (APHA, AWWA and WEF. 1999. Standard Methods for the Examination of Water and Wastewater, 20th ed. Washington, DC American Public Health Association). The metal in the solid phase may be determined nondestructively by x-ray fluorescence or diffraction techniques. 

Elemental composition Cd 53.92%, 0 30.70%, S 15.38%. CdS04 is dissolved in water and cadmium is analysed by atomic absorption or emission spectrophotometry, following appropriate dilution (see Cadmium). Sulfate ion in the solution may be determined by ion-chromatography or by gravimetry following treatment with barium chloride solution. 

Calcium may be analyzed by several instrumental techniques such as atomic absorption and emission spectrophotometry, ICP—MS, neutron activation, and x-ray fluorescence and diffraction methods. For all these techniques,... 

Cesium can be analyzed by various instrumental techniques including atomic absorption and atomic emission spectrophotometry and various x-ray methods. The most sensitive wavelength for AA measurement is 852.1 nm. It imparts a reddish violet color to flame. It is identified by specific line spectra having two bright lines in the blue region and several other lines in the red, yellow, and green. 

Erbium may be analyzed by atomic absorption or emission spectrophotometry. Other instrumental analyses involve ICP-MS and x-ray techniques. 

Elemental composition H 2.49%, Se 97.51%. The gas may be analyzed by GC using a TCD, FID or a flame photometric detector. The compound may be identified by GC/MS the molecular ions have masses 82 and 80. The compound may be absorbed in water and the solution analyzed for elemental selenium by flame or furnace atomic absorption—or by ICP atomic emission spectrophotometry. 

Terbium may be identified by various instrumental techniques including atomic absorption and emission spectrophotometry and neutron activation analysis. 

Thuhum may be determined by atomic absorption and emission spectrophotometry. The metal and its compounds are dissolved in acids and diluted appropriately before analysis. Thuhum also can be measured by neutron activation analysis. 

First the responses Rq are measured for the sample. Thereafter K is determined by fitting the changes in the concentrations of the analytes in the sample, brought about by the standard additions, to the changes in the responses. Once all elements in the calibration matrix, K, have been determined, the concentration vector of the analytes in the sample is calculated. The method has been successfully applied to absorption spectrophotometry , anodic stripping voltametry and ICP-atomic emission spectrophotometry Attractive features of the method are that automation is very easy and automatic drift compensation is possible . A drawback is that all interferents should be known and be corrected for. 

A Modular Raman Spectroscopy Using a Helium-Neon Laser That Is Also Suited for Emission Spectrophotometry Experiments 29... 

In addition, some metals may be determined by other methods, including ion-selective electrode, ion chromatography, electrophoresis, neutron activation analysis, redox titration, and gravimetry. Atomic absorption or emission spectrophotometry is the method of choice, because it is rapid, convenient, and gives the low detection levels as required in the environmental analysis. Although colorimetry methods can give accurate results, they are time consuming and a detection limit below 10 pg/L is difficult to achieve for most metals. 

Aqueous and nonaqueous samples must be digested with an acid before their analysis by atomic absorption or atomic emission spectrophotometry. The metals and their salts present in the sample are converted into their nitrates due to the fact that the nitrates of all metals are soluble in water. Therefore, concentrated nitric acid by itself or in conjunction with hydrochloric acid, sulfuric acid, perchloric acid, or hydrofluoric acid is used in sample digestion for the determination of total metals. Nitric acid alone is, however, adequate for digestion of most metals. Table 1.8.1 lists the combinations of acids that may be helpful in sample digestion. 

The following method employs atomic emission spectrophotometry (flame photometry), and is... 

Aluminum, silicon and zinc were determined by d.c.-argon plasma jet emission spectrophotometry. 

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