Determinations hydrocarbons

Sulfur, and tetraethyllead, simultaneous determination by modified differential absorptiometry, 144, 145 determination by x-ray emission spectrography, 66, 67, 329 in biological samples, determination by monochromatic x-ray absorption-edge method, 299-301 in hydrocarbons, determination by monochromatic absorptiometry, 130-135... 

The ratio of hydrocarbons, determined in experiments with a large excess of BuiSnH, as a function of temperature is given by32... 

Yield of hydrocarbon determined by gas chromatography after hydrolysis. 

Krzyzanowska, T., Szeliga, J. (1978) A method for the solubility of individual hydrocarbons determining in water. Nafta (Katowice) 34(12), 413—417. 

Petroleum pollution monitoring laboratories in the Mediterranean region participated (1984-1986) in two intercalibration exercises (MEDCALI and II) to evaluate the International Oceanographic Commission (IOC) Manual for petroleum hydrocarbon determination in sediment (IOC, Manuals and Guides, No. 11). The main source of error in the analysis was the extraction/ partition step. When the results were corrected for recoveries, relative standard deviations for w-alkancs, UCM (unresolved complex mixture) and total aromatics, which had previously been 60, 56 and 49%, respectively, were reduced to 17, 30 and 6%, respectively. 

The determination of hydrocarbon contaminants in soil is one of the most frequently performed analyses in the study of contaminated sites and is also one of the least standardized. Given the wide variety of hydrocarbon contaminants that can potentially enter and exist in the soil environment, a need exists for methods that quantify these chemicals satisfactorily. Formerly, the idea of total hydrocarbon determination in soil was seen as providing a satisfactory tool for assessing contaminated sites, but the nature of the method and the site specificity dictate a risk-based approach in data assessment. Quantitation of particular hydrocarbon species may be required. 

The symmetries characteristic of the parent hydrocarbons, determine the symmetry of the l,n + 2-disubstituted derivatives, 111, 112, 113, and 114, where A represents an achiral substituent. 

Aniline, determination of impurities in 321 Aromatic hydrocarbons, determination of 343, 389, 394, 400... 

Several effects such as chloracne and alterations in hepatic metabolism have been associated with exposure to 2,3,7,8-TCDD in humans. However, these effects are not specific for 2,3,7,8-TCDD or other CDDs, but may be induced by numerous other chlorinated hydrocarbons. Determination of specific biomarkers of effect for CDD and development of reliable methods to quantify these effects would be useful in assessing the effects associated with exposure to CDDs. 

Either IR or mass spectrometry may be used for individual hydrocarbon determination. Laser-induced Doppler absorption radar (LIDAR) can be used to remotely measure chemical concentrations in the atmosphere. Two different laser wavelengths are selected so that the molecule of interest absorbs one of the wavelengths, whereas the other wavelength is selected to be in a region of minimal interference. The difference in intensity of the two returned laser signals is then used to determine the concentration (see Figure 3.16, which illustrates the concept for IR signals). 

Ultraviolet Absorbance (polynuclear hydrocarbons) Determine as directed in the U.S. Food and Dmg Administration regulation for Petroleum Wax (21 CFR 172.886). 

Consider a sample of a hydrocarbon (a compound consisting of only carbon and hydrogen) at 0.959 atm and 298 K. Upon combusting the entire sample in oxygen, you collect a mixture of gaseous carbon dioxide and water vapor at 1.51 atm and 375 K. This mixture has a density of 1.391 g/L and occupies a volume four times as large as that of the pure hydrocarbon. Determine the molecular formula of the hydrocarbon. 

Hasty E, Revesz F. 1995. Total petroleum hydrocarbon determination by microwave solvent extraction. American Laboratory 27(4) 66. 

Huckel theory was used to confirm the electron affinities of aromatic hydrocarbons determined with the ECD. Figure 6.18 shows the Ea for several aromatic hydrocarbons calculated from a linear correlation of the Huckel coefficients of the lowest unoccupied molecular orbital (LUMO) versus the EvV from gas phase... 

The Ea are considered according to the methods used. Those for hydrocarbons determined by other methods are compared with the ECD values. The Ea for ben-zaldehydes, acetophenones, benzophenones, bezonitriles, esters, and nitrobenzenes have been determined by the ECD, TCT, and/or NIMS methods. These compounds and related molecules obtained from reduction potentials and charge transfer complex energies will be evaluated. Based on these data, the substitution effects for CH3C=0, N02, HC=0, NH2, F, Cl, and CF3 and the alkyl groups are determined. The multiple substitution effects of N02 and CN on benzene and ethylene are also established. 

Babich H, Sardana MK. Borenfreund E. 1988. Acute cytotoxicities of polynuclear aromatic hydrocarbons determined in vitro wWn the human liver tumor cell line, HepG2. Cell Biol Toxicol 4(3) 295-309. 

The following table gives exchange rates in methanolic NaOCHj and pA values for some hydrocarbons. Determine if there is a correlation between the kinetic and thermodynamic acidity. 

The molecular mass of the hydrocarbon determines how high it rises in the tower. 

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