Flame photometry compounds

Sulphur compounds Flame photometry Coulometry UV fluorescence... 

Metallic salts (or metallic compounds) after dissolution in appropriate solvents when introduced into a flame (for instance acetylene burning in oxygen at 3200°C), turns into its vapours that essentially contain mostly the atoms of the metal. Quite a few such gaseous metal atoms are usually raised to a particular high energy level that enables them to allow the emission of radiation characteristics features of the metal for example-the characteristic flame colourations of metals frequently encountered in simple organic compounds such as Na-yellow, Ca-brick-red Ba-apple-green. This forms the fundamental basis of initially called Flame Photometry, but more recently known as Flame Emission Spectroscopy (FES). 

A number of instrumental analytical techniques can be used to measure the total phosphorus content of organophosphorus compounds, regardless of the chemical bonding of phosphorus within the molecules, as opposed to the determination of phosphate in mineralized samples. If the substances are soluble, there is no need for their destruction and for the conversion of phosphorus into phosphate, a considerable advantage over chemical procedures. The most important methods are flame photometry and inductively coupled plasma atomic emission spectrometry the previously described atomic absorption spectrometry is sometimes useful. 

The flame photometry detector is specific for compounds containing sulphur or phosphorous. Compounds eluting from the column are burned in a flame hot enough to excite these elements and induce photonic emission, which is detected by a photomultiplier (see Fig. 2.12). Optical filters are used in the detection system to... 

Ultrafiltration was applied to examine the size fractionation of Al, Ca, Cu, Fe, K, Na, and Pb in white and red wines [91]. Metal determinations were performed on the unfiltered wine, the 0.45 p,m membrane-filtered wine and each ultrafiltrate fraction. Aluminum was determined by ET-AAS, while FAAS was employed for Cu and Fe. An electroanalytical technique, stripping potentiometry, was selected for Pb measurement, whereas flame photometry was chosen for K and Na quantification. Fractionation patterns were evaluated and discussed. Castineira et al. [92] combined on-line tangential-flow multistage ultrafiltration with a home-built carbon analyzer and ICP-MS for size fractionation of nonvolatile dissolved organic compounds and metal species in three German white wines. The study showed that the major part of the elements investigated (up to 25) were dissolved in the size fraction of < 1 kDa, with the exception of Ba, Pb, and Sr, which also appeared in other fractions. 

After the equilibration period, clearance periods of 20 min are used. Urine samples are collected and perfusate is obtained at midpoint of the clearance period for the evaluation of overall kidney function. For determination of glomerular filtration rate (GFR) and fluid transport, 3H-labelled polyethylene glycol is added to a modified Krebs-Henseleit bicarbonate buffer. Electrolytes are determined in urine by standard flame photometry. Fractional excretions of water, electrolytes and test compounds are calculated. 

As well as the atomic spectroscopic methods of flame photometry and atomic absorption spectroscopy microwave emission spectroscopic detection (MED) is being used more and more. MED combines high sensitivity in the picogram range with high selectivity for elemental analysis. It is as suitable for inorganic and organic compounds... 

Because carbon dioxide is nonpolar, the separation of polar compounds by supercritical carbon dioxide is difficult. Thus, polar modifiers are often used for the separation of phenols and amines. Derivatization has also been employed to obtain nonpolar analytes in some applications. The UV detector has mainly been used for the detection of polar compounds. Oxidative and reductive amperometric detection was also utilized with a detection limit of 250 pg for oxidative detection of 2,6-dimethylphenol. The detection of amines has generally been achieved by FID. Other detectors used for the detection of polar analytes include Fourier transform infrared (FTIR), photodiode array, and flame photometry. 

The organotin compounds R SnX are extracted then converted into the hydrides R SnH4 with NaBH4, or, more usually, are alkylated to R SnR 4 with a Grignard reagent or with NaBEt4. These volatile, relatively non-polar, compounds are then separated by GLC or HPLC and analysed by techniques such as atomic absorption, flame photometry, or mass spectrometry.43 45 At the moment GLC-FP or GLC-MS appear to give the best performance, but of the four steps that are involved in the analysis, namely extraction, derivatisation, separation, and detection, it is not the analysis itself, but rather the extraction and derivatisation that are the major source of errors and are most in need of improvement. 

The principle of flame photometry is employed in a specific GC detector very sensitive to the element sulfur and also in other specialized analysers. So, in GC, when an organo-sulfur compound is pyrolysed in the burner of the detector, the air-hydrogen flame reduces the compound to elemental sulphur which emits radiation of wavelength 394 nm. 

Gas chromatography [15], flame photometry [9] and sometimes flame photometry in combination with gas chromatography are used for the detection of sulphur dioxide and other gaseous sulphur compounds. The gas is burned in a hydrogen flame, and the sulphur emission line at 394 nm is measured. 

See alsa Atomic Absorption Spectrometry Electrothermal. Atomic Emission Spectrometry Flame Photometry. Cadmium. Carbon. Chemiiuminescence Overview. Fluorescence Environmental Applications. Gas Chromatography Environmental Applications. Laser-Based Techniques. Lead. Nitrogen. Ozone. Polycyclic Aromatic Hydrocarbons Environmental Applications. Remote Gas Sensing Overview. Spectrophotometry Inorganic Compounds. Sulfur. X-Ray Fluorescence and Emission X-Ray Fluorescence Theory. 

Provided it can be excited, the HPO emission is very specific for the identification of P (Figure 14.2). Detection limits down to 0.01 mg/mL of P from the HPO line at 5262 A, and 1 mg/mL of P from the PO line at 2464 A can be reached. These limits are very variable, however, and depend not only on the matrix, but on the nature of the phosphorus compound and the excitation technique which is used. Flame photometry, using HPO emission is in widescale use for the quantitative analysis of organophosphorus pesticides and their decomposition products. 

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