Separation factor acetonitrile phosphate buffers

This has been repeatedly confirmed in several studies see, for example. Figure 4.4. Here, the retention (bars) and separation factors (lines) of tricyclic antidepressants in acidic acetonitrile/phosphate buffer are shown. In the case of quite different retention factors depending on the hydrophobic character of the phases (differently strong interactions), apart from a few exceptions very similar separation factors result. Although the analytes are retained for different lengths of time on the stationary phases, they show a similar selectivity behavior. This is observed especially with neutral or - by means of the pH-neutralized molecules. In this case, mainly hydrophobic interactions between the analytes and the surface of the material dominate. These are not especially specific the individual differences of the phases with respect to selectivity do not come into effect. 

Chem. 2 Comparison according to all separation factors in acidic/alkaline methanol/acetonitrile phosphate buffers, S2. 

Chem. 18 Comparison according to separation factors in acidic acetonitrile/phosphate buffer, SI. 

Results after annealing of the polymers under vacuum in the dry state at 120°C for 24 h and heating of the polymers at 130°C for 4 h in the mobile phase. The MIP using benzene (C6H6) as diluent was evaluated using acetonitrile/0.05 M potassium phosphate buffer, pH 7 7/3 (v/v) as mobile phase. The separation factor prior to the heat treatment was 4.1 in this mobile phase. Data from [7]... 

Fig. 5.37. 3D-representation of the capacity factors of five different triazines injected separately (10 nmol) on a reference column (REF), an ATR imprinted column and a PRO imprinted column in the mobile phase acetonitrile/potassium phosphate buffer, 0.05 M, pH 4 30/70 (v/v). The amount of CYA injected on the reference column was 100 nmol. The hydrophobicity of the triazines decrease from front to back of the graph. From Dauwe and Sellergren [32]. 

The pH of the phosphate buffer as well as the percent acetonitrile in the mobile phase are the major factors affecting the separation of the anilines on the C-18 columns. By employing a low pH, the halogenated aniline compounds are separated not as the neutral free bases but as their corresponding anilinium ions. Thus the use of a lower pH buffer will decrease the elution time for all the compounds (74). 

Fig. 8. On the bandwith of retention and separation factors by the separation of metabolites of tricyclic anti-depressants in acetonitrile/acidic phosphate buffer.

The effects of different factors on the chiral separation have been investigated. These were the cyclodextiin t5q>es, the concentration, pH, the nature of the organic solvents and the phosphate buffer concentration. The mobile phase consisted of acetonitrile and 10 mmol of sulfobutyl ether-/3-cyclodextiin. The pH of 4.0 was adjusted with phosphoric acid. The investigated method was able to separate the three racemates (52). 

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