Propyl-bonded phase

The Separation of Some Proteins and a Peptide on a Glyceryl-Propyl Bonded Phase... 

Name 3-(p-Acetylphenoxy) propyl bonded phase Structure ... 

The disadvantage of normal phase HPLC for the separation of carbonyl dinitrophenylhydrazones is the difficulty in maintaining reproducible retention times due to absorption of water from the solvent and interaction with the active groups on the column (Fig. 5.10). To overcome this problem, a cyano-propyl bonded phase (Exsil 100, 5 /im Chromtech, U.K.) column may be used for isolation of hy-droxyalkenals and a mixture of alkanals and alk-2-enals from rat liver microsomes. The less polar carbonyls can be separated under isocratic conditions as follows. 

An alternative for the same kind of analysis are silica columns that have been dynamically coated with a polyamine. Triethylene tetramine or natural amines such as spermidine or putrescine are suitable for this purpose. Small differences in selectivity are observed when different amines ate used. Dynamically coated packings give a more stable chromatography than do amino-propyl bonded phases, but the silica is still subject to slow dissolution. Therefore a silica with a strong skeleton ( = small specific pore volume) is recommended for this application. 

The i-butyl ester derivatives of the d- and /-A -acetyl amino acids, S- benzylcys-teine, N-i-butyltryptophan, phenylglycine, and phenylalanine were well resolved (a > 1.3) with k values <2.5 using 70/30 hexane/DCM or 70/30 hexane/chloro-form mobile phases on a (iV-formyl-L-valinylamino)propyl bonded phase (2 = 230 nm). The use of aprotic mobile phase modifiers, instead of the more commonly used alcohols, resulted in greater separation between enantiomers (as determined by... 

The preparation of the lemon juice for analysis was simple, a sample of the lemon juice was filtered and 5 pi placed on the column. The separation was carried out on a novel bonded phase carrying amino-propyl groups. The separation obtained is shown in figure 11. 

The bonded phases carrying polar groups such as -NH2, -OH, -CN, etc., which are separated from the packing surface by a spacer (usually the n-propyl groups) behave in an intermediate manner between the solid surfaces and the nonpolar bonded phases though the effect of polar end groups usually dominates (Sections 16.3.5 and 16.3.6). 

Bonded amine Si-O-Si-C -ch2ch2ch2-nh2 Polar bonded phase Selectivity is modified with respect to silica through the aminopropyl functionality the propyl linkage can interact... 

Propyl, ethylene diamine Si-O-Si-C -CH2CH2CH2-NHCH2CH2NH2 Ion exchange Weak anion exchange phase for aqueous and biological samples incorporates a bidentate ligand to form chelate complexes useful for metal separations less polar than the propyl amine bonded phase... 

Conditions Bonded phase - 3 experimental batches of propyl nitrile,... 

During the 1990s, the use of HPLC and 2-(l-pyrenyl)ethyldimethylsilylated silica (PYE) to separate planar compounds has become more and more common, cf. Fig. 3. For example, PCNs and non-orfho-PCBs have been separated from the bulk of PCBs using the PYE column with n-hexane as the mobile phase [8,213]. The PYE phase and similar electron-donor-bonded phases such as 3-(N-carbazolyl)propyl-silyl (CZP) are hitherto the only ones reported to separate 1,2,3,4,6,7-hexaCN (CN-66) and 1,2,3,5,6,7-hexaCN (CN-67) [14,166,167,214,215 ].It is notable that the CZP phase separates 1,2,3,4,6,7-hexaCN (CN-66) and 1,2,3,5,6,7-hexaCN (CN-67) with the opposite elution order compared to the PYE phase [215]. 

Because HIC supports are designed for macromolecules, they either possess pore diameters of at least 300 A to allow inclusion or are nonporous. Both silica and polymer matrices are used because the hydrophilic polymeric coating minimizes or ehminates most matrix-based effects. The absolute retention and selectivity of an HIC support may be affected by the specific composition of the bonded phase, as well as the ligand. For example, protein mixtures have shown distinct selectivity on different HIC columns which have propyl functional groups [5]. 

Polar bonded phases for normal-phase separations have recently gained popularity. These include the dihydroxypropyl propyl ether (diol), aminopropyl, cyanopropyl, and nitrophenyl bonded silicas. These phases are advantageous to silica because they are less active and, yet, produce similar interactions, require shorter equilibration times, and are influenced less by the water content of the mobile phase. The retention of most analytes upon the diol and amino phases is similar to that of the parent silica and alumnia, whereas the cyanopropyl and nitrophenyl phases generally show less retention. 

Fig. 7.6. Separation of heroin and some common adulterants and contaminations Column amino-propyl bonded silica (S5NH.)(Phase-Sep) (250x4 mm ID), mobile phase acetonitrile - 0.005 M tetrabutylammoniurn phosphate (85 15), flow rate 1 ml/min, detection UV 284 nm. Peaks 1, noscapine 2, papaverine 3, caffeine 4, heroin 5, acetylcodeine 6, 6-0-acetyl-morphine 7, codeine 8, strychnine 9, morphine, (Reproduced with permission from ref. 93, by the courtesy of Journal Chromatographic Science)...

There are three general types of bonded normal-phase sorbents aminopropyl, cyanopropyl, and diol (Fig. 5.3). All three are derivatized as a propyl hydrocarbon, which places them near the surface of the silica. Only the cyanopropyl sorbent is available in either endcapped or nonendcapped forms (Table 5.1). Thus, analytes have the opportunity to interact not only with the bonded phase but also with the underlying silica sorbent. Furthermore, because the hydrocarbon chain is short, only three carbons in length, the... 

As practiced, normal phase is very much like the adsorption mode (polar stationary-phase surface and nonpolar mobile phase), the only difference being that the normal-phase separation is done on a less-polar surface. This is because the sorbent used in normal-phase separations is bonded with a polar-bonded phase, such as propyl cyano, propyl amino, or organo-diol (from a reagent derived from glycerol). Although select vities are similar to the adsorption mode, the reproducibility is greatly increased due to less sensitivity to moisture in the mobile phase due to a lower silanol content. 

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