Dating organically precipitated

The concentration of the transferred ion in organic solution inside the pore can become much higher than its concentration in the bulk aqueous phase [15]. (This is likely to happen if r <5c d.) In this case, the transferred ion may react with an oppositely charged ion from the supporting electrolyte to form a precipitate that can plug the microhole. This may be one of the reasons why steady-state measurements at the microhole-supported ITIES are typically not very accurate and reproducible [16]. Another problem with microhole voltammetry is that the exact location of the interface within the hole is unknown. The uncertainty of and 4, values affects the reliability of the evaluation of the formal transfer potential from Eq. (5). The latter value is essential for the quantitative analysis of IT kinetics [17]. Because of the above problems no quantitative kinetic measurements employing microhole ITIES have been reported to date and the theory for kinetically controlled CT reactions has yet to be developed. 

As has been described above, HA is an essential functional component of almost all tissues in the vertebrate organism. Thus, various animal tissues - e.g. rooster combs, shark skin, bovine eyeballs - have been used as sources of isolation and production of high molar mass HAs. Since in the biological materials HA is usually present in a complex linked to other biopolymers, several separation procedures have to be applied in order to obtain a pure compound, such as protease digestion, HA ion-pair precipitation (with e.g. cetylpyridinium chloride), membrane ultrafiltration, HA non-solvent precipitation and/or lyophilization [135,136]. The mean molar mass of the commercially available extractive HA preparations obtained from animal tissues is mostly in the range from several hundred thousands Da up to approximately 2.5 MDa. To date, the demand for HA materials approved for applications in human medicine has been satisfied by high molar mass HAs prepared from the rooster combs. For example, Healon (Pharmacia Upjohn, Inc., Peapack, NJ, USA) - used in viscosurgery at eye implant insertion - has a mean HA molar mass of about 2.5 MDa. 

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