Organic-aqueous partitions

Separation of the modified peptide from the released glycan may be accomplished using a Cig cartridge and the glycan then isolated from the unretained fraction by acid-catalyzed acetylation and organic/aqueous partition. Tandem mass-spectrometric analysis of the recovered peptide yields sequence information allowing location of the modified amino acid. 

Here, is the partition coefficient between the organic acceptor phase and the aqueous donor (sample) phase. For acidic or basic compounds ar> is given by Equation 12.3 or 12.4, while for non-chargeable compounds d = 1- Thus in MMLLE, the organic/aqueous partition coefficient directly governs the extraction. 

Whitehouse, B. 1985. The effects of dissolved organic matter on the aqueous partitioning of polynuclear aromatic hydrocarbons. Estuar. Coastal Shelf Sci. 20 393-402. 

Spurlock, F.C. and Biggar, J.W. Thermodynamics of organic chemical partition in soils. 2. Nonlinear partition of substituted phenylureas from aqueous solution. Environ. Sci Technol., 28(6) 996-1002, 1994. 

Furthermore, for most compounds of interest to us, the octanol molecules present as cosolutes in the aqueous phase will have only a minor effect on the other organic compounds activity coefficients. Also, the activity coefficients of a series of apolar, monopolar, and bipolar compounds in wet versus dry octanol shows that, in most cases, Yu values changes by less than a factor of 2 to 3 when water is present in wet octanol (Dallas and Carr, 1992 Sherman et al., 1996 Komp and McLachlan, 1997a). Hence, as a first approximation, for nonpolar solvents, for w-octanol, and possibly for other solvents exhibiting polar groups, we may use Eq. 6-11 as a first approximation to estimate air- dry organic solvent partition constants for organic compounds as illustrated in Fig. 6.2. Conversely, experimental KM data may be used to estimate K,aw or Kitvi, if one or the other of these two constants is known. 

Because PAHs are hydrophobic, they tend to accumulate in lipids of organisms that are unable to metabolize them. There are several partition coefficients that can describe the accumulation of PAHs in organisms. Direct partitioning of aqueous phase PAHs to an organism is described by the bioconcentration factor ... 

Multi-phase reactors are of interest in biocatalytic reactions if one or several components of the reaction are insoluble or insufficiently soluble in aqueous phases but if an aqueous phase has to be kept, if only for the biocatalyst. However, a two-phase system can be utilized advantageously for the shifting of an equilibrium this is demonstrated below. We analyze the simple reaction A <=> B in an organic-aqueous two-phase system with the assumption that reactant A and product B partition between the two phases. The partition coefficients Pw and Porg are de-... 

Listeria monocytogenes cells partitioned between organic/ aqueous medium Poly(allylamine) used in presence of diacid chloride Polymeric microcapsules (bacteria-mediated lithography) NS Aheme et al., 1996 Whitcombe et al., 1997... 

Sorption of organic contaminants onto aquifer solids is frequently described as a partitioning process, where the hydrophobic organic compound partitions into natural organic material associated with the aquifer solids [8]. Sorption can be characterized as either an equilibrium or rate-limited phenomenon. Equilibrium sorption can be modeled as either a linear or non-linear process. Equilibrium sorption may be assumed when the flow of groundwater and other processes affecting contaminant transport are slow compared to the rate of sorption. In this event the sorption of the contaminant can be considered instantaneous. If we assume equilibrium sorption, the relationship between sorbed and aqueous contaminant concentrations may be described by a sorption isotherm. 

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