Sensitizer from -2-octanol

Using separation-optimized SI with 0.05 M HN03 as the eluent and 1-octanol saturated solutions, 90Sr recoveries were 96%, and carryover from one sample into a subsequent blank run was typically 1-2% 47 Blank runs or column clean-up procedures can be used to reduce or eliminate carryover between samples. Recoveries were not sensitive to elution flow rates, and columns could be used repeatedly. There were no significant performance differences between Sr-Resin materials with 20-50... 

To help establish the relevance of a skin sensitization alert from DEREK for Windows, the system incorporates reasoning that allows the determination of skin permeability coefficients (log Kp values) according to the algorithm developed by Potts and Guy (1990). DEREK for Windows derives log Kp from the logarithm of the octanol/water partition coefficient (log Kow) using the following equation (Moriguchi et al., 1992) ... 

With the proper choice of solvent volume and sensitive analytical methods, logP values ranging from —5 to -1-5 can be measured. The temperature dependence of many partitioning systems is on the order of 0.01 log unit per degree in the 25°C range. Adequate temperature control is needed for high accuracy. This is more critical for volatile solvents like ether, choloro-form, low-boiling hydrocarbons, and alcohols lower than 1-octanol. 

It has been suggested that a suitable surrogate parameter for atmosphere/plant partition is the octanol/air partition coefficient (Harner and Mackay 1995). Direct measurements of this coefficient for a number of chlorinated aromatic hydrocarbons revealed, however, its sensitivity to temperature. The results of a study in which a number of PAHs were analyzed throughout the year in samples of tree bark, leaves, pine needles, and in the atmosphere also underscore the importance of temperature, since there was a cyclical partition between the atmosphere and the tree canopy (Simonich and Hites 1994). The contribution to the atmosphere through direct volatilization from the terrestrial environment was not resolved in this study. 

In another study (13), a semicarbazide coating was prepared by dissolving 100 mg of semicarbazide hydrochloride in 10 ml of 1 1 acetone/ethanol, followed by the addition of 5 ml of 6 M ammonia solution. The clear solution was allowed to stand to ensure neutralization of the hydrochloric acid before application to the crystal electrodes. The coated 9 MHz crystal was driven at its third overtone of 27 MHz. The detector had a sensitivity of 12.4 Hz jjI and a linear response in the concentration range 5.50 tjg 1. the highest response was obtained in a dry nitrogen stream at a flow rate of 90 ml min, and decreased to about 33% in a wet air stream (58% relative humidity) at a flow rate of 200 ml min". The relative sensitivities to the potential intererences studied (chloroform, acetaldehyde, ethanol, acetone, n-octanol, ethyl-butyrate and n-hexylacetate) ranged from 0.000000 to 0.000029 compared to a relative response of one to acetoin. 

The applications of solvent-tolerant strains in microbial production processes are at present limited, but two strategic options are currently available to use such bacteria. Relevant genes can be introduced into solvent-tolerant organisms in order to produce the required product. This approach has been followed successfully by J. Wery in our laboratory who employed an 1-octanol-aqueous system. Methylcatechol was produced from toluene by solvent tolerant P. putida S12. Alternatively, the efflux pump can be expressed in a suitable solvent-sensitive host which would then be more tolerant for a particular solvent. 

The advantages of the coulometric method are its simplicity of operation, its increased sensitivity, and the fact that it does not require a standardized reagent, such as water saturated 1-octanol, to calculate the water content but only to assess the accuracy of the instrument. The advantage of the volumetric method is that it permits the use of a wider range of very polar solvents as well as nonpolar solvents for dissolving the sample in the titration vessel. Furthermore, the volumetric titration vessel can be heated to enhance the dissolution of slightly soluble samples. Either the volumetric or the coulometric titration instrument can be joined with an oven (evaporation) or a distillation apparatus (azeotropic distillation). In this configuration, the moisture that is volatilized from the sample can be transported to the titrator with a dry gas and the evaporated water measured either coulometrically or volumetrically. The recent... 

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