solution. They then analyzed the fiber by gas chromatography with flame ionization detection. After extraction times were optimized to ensure equilibrium, the method showed an RSD of less than 5% with good correlation to literature K[)w values. {Anal. Chem. 1996, 68(1), 130-33)
MODELING PAH in soils Given the toxicity and carcinogenic effects of polynuclear aromatic hydrocarbons (PAHs), knowing their environmental fate is important. S. Karimi-Lotfabad and colleagues investigated the PAH retention by montmorillonite clay and three other soils under varying times and moisture contents. Anthracene and, in some cases pyrene or phenanthrene was added to soils and extracted (EPA Method 3540) to evaluate the recoverable fraction of PAHs. As much as 100% of the anthracene and could not be extracted Phenanthrene was retained to a smaller deeree; UD to 25% was not extractable More detailed experiindicated that PAHs may oliffnmpn7P to higher weight aromatics Water inhibited the reaction but t^ rpactinn occurred anthrarnulH not he biodppraded hv an active harterial culture The re lt aa tpd that air or o pn J
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Improving solubility prediction The water solubility of a chemical must be taken into account when predicting its fate and effect in the environment. However, this parameter often is unavailable and must be estimated from the octanol-water partition coefficient (Kovl). W. M. Meylan and co-workers reported significant improvements to the current method for predicting solubility. Building on the 276 compounds originally used to develop regression equations they determined solubility by calculating its regression against K using an additional 1450 compounds They also included melting point and molecular weight
Solid state speciation of lead A device that measures X-ray absorption or fluorescence, called EXAFS spectroscopy, has been applied to the speciation analysis of lead in solid fractions of contaminated soils. This technique probes the structural environment around atoms up to a distance of 3-4 A and is sensitive to changes in neighboring atoms. A. Manceau and co-workers demonstrated that a range of model lead precipitates exhibited different EXAFS spectra. Four groups of compounds were distinguished based on the average distances of lead to its nedfBst neighbor represented by Pb-salicylate -sulfate ids and -tetramethyl EXAFS was then iisefi a
