Alkyl lead compounds

Tetra-alkyl lead compounds in air Personal monitoring with atomic absorption analysis or electrothermal atomization or X-ray fluorescence spectrometry or on-site colorimetry 9... 

MDHS 9 Tetra alkyl lead compounds m air (personal monitonng)... 

Alkyl lead compounds are also highly neurotoxic and were implicated in large-scale kills of wading birds. 

Carbon disulphide methanol phenol n-hexane methyl n-butyl ketone organophosphorus compounds tetra-alkyl lead compounds. 

MDHS 14 General method for the gravimetric determination of respirable and total dust MDHS 15 Carbon disulphide MDHS 16 Mercury vapour in air Laboratory method using hopcalite adsorbent tubes, and acid dissolution with cold vapour atomic absorption spectrometric analysis MDHS 17 Benzene in air Laboratory method using charcoal adsorbent tubes, solvent desorption and gas chromatography MDHS 18 Tetra alkyl lead compounds in air Continuous on-site monitoring method using PAC Check atomic absorption spirometry... 

MDHS9 Tetra alkyl lead compounds in air (personal monitoring). 

There is considerable interest in the removal of contaminants from the sites of former gas-lilling stations. The surrounding soil is contaminated not only with fuel hydrocarbon residues, but also with alkyl lead compounds that were previously used as gasoline additives. It has been shown... 

Organic Lead. Alkyl lead compounds are actively metabolized in the liver by oxidative dealkylation catalyzed by cytochrome P-450. 

Relatively few human studies that address the metabolism of alkyl lead compounds were found in the available literature. The dealkylation, mediated by cytochrome P-450, of alkyl lead compounds is thought to occur in the rat, mouse, and rabbit. This step converts tetraethyl and tetramethyl lead to the... 

Harrison RM, Radojevic M, Wilson SJ. 1986. The chemical composition of highway drainage waters IV. Alkyl lead compounds in runoff waters. Sci Total Environ 50 129-137. 

Hewitt CN, Harrison RM. 1987. Atmospheric concentrations and chemistry of alkyl lead compounds and environmental alkylation of lead. Environ Sci Technol 21 260-266. 

Heterogeneous route, at the electrode surface. The lead anode is attacked and yields tetraethyllead as the main product. For this stage, several reaction routes are possible, e.g. diethylcadmium may be oxidized on the lead anode to produce ethyl radicals which, in turn, may oxidize metallic lead. Partially alkylated lead compounds thus formed are alkylated to tetraethyllead by ethyl iodide. 

Reisinger et al. [21] used the gas chromatographic-atomic absorption spectrometric technique to demonstrate that biomethylation of inorganic lead does not account for the presence of organolead compounds in sediments. Sulphide induced chemical conversion of organic lead(IV) salts into alkyl lead compounds is, however, possible. 

Conversion to tetra-alkyl lead compounds using nBu MgCI then gas chromatography with atomic absorption spectrometric detector Petroleum ether extraction, glc... 

Alkyl lead compounds are extremely effective gasoline antiknock agents. By decomposing to form lead oxide compounds during the gasoline combustion process, lead alkyls interrupt the rapid chain scission reactions which lead to combustion knock. Also, lead alkyls help to prevent exhaust valve seat wear and may minimize octane requirement increase. However, unless utilized in conjunction with lead scavengers such as 1,2-dichloromethane, lead deposits can accumulate within the gasoline combustion chamber. 

Fuel sulfur can decompose alkyl lead compounds and can diminish the effectiveness of lead compounds at inhibiting combustion knock. The effect of fuel sulfur at degrading alkyl lead compounds can be rated as follows ... 

C. Because they were used in gasoline to boost octane rating, alkyl lead compounds found their way into the environment as toxic pollutants. One way to measure lead compounds in natural waters is by anodic stripping voltammetry (Figure 17-20), in which the lead is first reduced to the element at a mercury electrode and dissolves in the mercury. Reoxidation occurs when the electrode potential is made sufficiently positive, with current proportional to the concentration of dissolved Pb. 

To demonstrate that coprecipitation of Pb2+ does not decrease the concentration of alkyl lead compounds, artificial seawater... 

SECOND-ORDER RATE COEFFICIENTS (l.mole- 1.SeC ) FOR THE ACIDOLYSIS OF ALKYL-TIN AND ALKYL-LEAD COMPOUNDS BY HYDROCHLORIC ACID IN METHANOL AT50 C63... 

Blais et al. [12] has described a method using HPLC coupled with AAS for the determination of ionic alkyl lead compounds in soils. They demonstrated that previously published methods gave poor recoveries of lead and the formation of artifacts during the isolation and derivatisation procedures. An alternative procedure is described involving a series of selective extractions... 

Air Lead Five tetra-alkyl lead compounds GC eluent introduced into flame-heated ceramic tube placed in light path. H2 introduced prior to tube to give diffusion flame 0.25mgPbmr3 Hewitt and Harrison (1985)... 

Radzuik, B., Thomassen, Y. and van Loon, J.C. (1979) Determination of alkyl lead compounds in air by gas chromatography and atomic absorption spectrometry. Anal. Chim. Acta, 105, 255-262. 

Wang, Y., Turnbull, A.B. and Harrison, R.M. (1997) Concentrations, phase partitioning and deposition of specific alkyl-lead compounds in the atmosphere. Appl. Organometal. Chem., 11, 889-901. 

Forsyth, D.S. and Iyengar, J.R. (1989) The determination of tetra-alkyl lead and ionic alkyl lead compounds in seafood. Appl. Organomet. Chem., 3, 211-218. 

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