Acetonitrile phase behavior

Thus, water in mixtnres with polar (DMSO, acetonitrile) and weakly (chloroform) polar organic solvents can form both complexes with electron-donor molecnles and large clnsters of SAW (as dispersion phase). In the mixtures with DMSO, the amount of ASW is greater than in the case of the mixtures with acetonitrile. The behavior of SAW in the mixtnres with DMSO and acetonitrile differs and this difference explains good properties of DMSO as a cryopreservative preventing the formation of large SAW structures (i.e., ice crystallites). 

A general method for the successful recrystallization of such surfactants in good yields has been found that exploits both kinds of phase behavior [99]. In the case of CgAH, for example, the compound may be mixed with acetonitrile (a solvent in which it is poorly soluble) and dissolved by the addition of water or a lower alcohol (methanol, ethanol, isopropanol). Such mixtures are often very good solvents for such compounds but do not yield the crystal phase in acceptable yields on cooling. 

Mark-Houwink constants for PEG, PEO, and PSC are summarized in Table 20.4. These were measured in either an aqueous mobile phase of 0.10 N NaNOi or a mobile phase of 20% acetonitrile in aqueous 0.10 N NaNOi (which also exhibits universal calibration behavior). The values for a fall within... 

The apparent rate constant kapp depends on the concentration of hydroxide ion as is shown in Fig. 1. The absorption maxima of TcCl2(acac) 2 in chloroform appear at 281,314(sh), 340(sh), 382 and 420 nm. On the other hand, the spectrum of the aqueous phase exhibits absorption maxima at 292,350 and 540 nm. The absorbances at 350 and 540 nm increase with time, but decrease after reaching maxima. This suggests that the chemical species which is formed by the back-extraction of TcCl2(acac)2 decomposes with time. In order to clarify the behavior of chloride ion liberated from the complex, an electrochemical method was introduced for the homogeneous system. In acetonitrile, no detectable change in the spectrum of TcCl2(acac)2 was observed. On the addition of an aqueous solution of hydroxide, however, the brown solution immediately turned red-violet, and exhibited absorption maxima at 292,350 and 540 nm. The red-violet... 

Figure 5.1 Retention behavior of two representative basic compounds (atenolol in red and pindolol in blue) on ZIC p-HILIC stationary phase fordifferent percentages of acetonitrile in mobile phase.

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