ODS-silica

Toyopearl HW-50S resin has been used to help isolate the ubiquitin-histone conjugate mH2A from the unicellular ciliated protozoan Tetrahymena pyriformis. Figure 4.49 shows the separation of mH2A from the histone, H2A. The sole difference between these two components is a small polypeptide, ubiquitin (approximately 8500 Da). The mH2A fraction was then further purified by HPLC on a Tosoh ODS-silica column (52). One of the many benefits... 

A polyethylene-coated (PEE) silica column was used with water-methanol eluents to achieve the separation and retention of 27 pesticides.40 The retention times of 33 commercial pesticides were determined on an octadecyl (ODS)-derivatized alumina column using water-methanol eluents and compared with retention properties on an ODS-silica column packing.41 More recently, RP-HPLC was used in combination with diode array detection for the identification and quantification of 77 pesticides (acidic, basic, and neutral) in groundwater samples.42... 

Preparative HPLC of component II was difficult. Component II was collected with a resolution comparable to that shown in Figure 2. Higher resolution showed the presence of at least 5 minor peaks. Slowing the water/methanol gradient finally produced a single peak, which when collected, totaled 14 mg of slightly yellow oil from 2.1 gms OFAs extracted with ODS silica (16). Structural work on II has not yet appeared in the literature, so more detail is included. 

HPLC of other plant genera by ODS silica extraction produced complex chromatograms similar to that from E. mlcrocarpa. Pond waters from various sources were also screened for OFAs. These chromatograms were less complex than those from the plants and, notably, showed mostly compound I, and component II. Table III shows the occurrance of these compounds In plants and pond waters. 

When Winter senescent plant material was harvested and extracted, yields of OFAs were greatly reduced. OFAs from the four ponds were extracted easily from 20-50 liters of pond water by passing the water through a tube filled with ODS silica. These ponds produced between 1 and 1.5 ppm of OFAs after elution with methyl formate. The origin of I, Ila and lib in these ponds is uncertain at this time. 

Konemann, H., Zelle, R., Busser, F. (1979) Determination of log P, ict values of chloro-substituted benzenes, toluenes and anilines by high-performance liquid chromatography on ODS-silica. J. Chromatogr. 178, 559-565. 

Figure 3.10 Selectivity of phenyl-bonded silica gel compared with ODS silica gel.

Columns. ODS-silica, YMC ODS, 15 cm x 6.0 mm i.d., phenyl-bonded silica gel, YMC phenyl, 10 cm x 6.0 mm i.d. eluent, aqueous acetonitrile. Compounds, x, polycyclic aromatic hydrocarbons O, alkylbenzenes O,polychlorobenzenes +, alkanols A, alkanes 1, benzene 2, benzopyrene 3, toluene 4, heptylbenzene 5, hexachlorobenzene 6, hexanol 7, tetra-decanol 8, pentane and 9, octane. 

Alkanesulfonic acid Cetylpyridium Tris(2,2 -dipyridyl)ruthenium(ii)mono dicarboxylic acids ODS silica 60% aq. MeOH 17... 

The retention time of phenols was predicted in 70 and 60% acidic aqueous acetonitrile on an ODS silica gel column. The constants A, B, C, and D were obtained from the above equations. The result in 60% aqueous acetonitrile is shown in Figure 6.6. The correlation coefficients between the measured and predicted retention factors of substituted phenols in 60 and 70% acidic aqueous acetonitrile were 0.974 (n = 36) and 0.967 ( = 36), respectively. In this system, the values of the slopes, which indicate the relationship between the measured and predicted retention factors, were 0.81 and 0.94 in 60 and 70% acidic aqueous acetonitrile, respectively.32... 

Figure 6.8 Relationship of enthalpy to log k values. Column, ODS silica, ERC-ODS, 15 cm x 6.0 mm i.d. eluent, 80% aqueous acetonitrile at 30 °C. Numbers beside symbols see Table 6.4. O, Polycyclic aromatic hydrocarbons x, alkyl-benzenes, O, halogenated benzenes A, alkanols and , alkanes.

Racemic mixtures of underivatized amino acids Cu (II)-N - -decyl-L-histidine on ODS silica Water-Cu(II) acetate -1- organic modifier (85/15) 228... 

Interaction of naproxen with the surfaces of silica gel and ODS silica gel HPLC packings. 

Ibuprofen, an acidic drug, which has a pAia of 4.4, is analysed by chromatography ph ODS silica gel with a mobile phase consisting of acetonitrile/0.1 M acetate buffer pH 4.2 (40 60). 

The effect of pH on the HPLC retention time of an ionisable basic drug. Bupivacaine, which has a piSa of 8.1 is analysed by chromatography on ODS silica gel with a mobile phase consisting of acetonitrile/TRIS buffer pH 8.4 (40 60) at a flow rate of 1 ml/min. The t for the column at a mobile phase flow rate of 1 ml/min is 2.3 min. The retention time of bupivacaine at pH 8.4 is 17.32. If jJf app is the apparent capacity factor Of the partially ionised drug, then for a base ... 

Goewie et al. (19) developed an organometallic-silica bonded phase for the selective retention of phenylurea herbicides and anilines from water. Seven-micrometer diameter silica was derivatized with 2-amino-1-cyclopentene-l-dithiocarboxylic acid (ACDA), resulting in Structure I. Capacity factors of phenylurea herbicides and corresponding anilines were measured on the ACDA-silica and ACDA-metal-loaded silica. The platinum-loaded material was found to selectively retain the anilines. Anilines could be eluted with acetonitrile, but not with methanol or tetrahydrofuran, because of the strength with which acetonitrile forms complexes with platinum and thus displaces the anilines. Application of the ACDA-Pt precolumn in series with an ODS-silica precolumn for... 

Ethoxyquin Standard of ethoxyquin 250 X 4.6-mm-ID column packed with ODS-silica... 

Monolithic silica columns can be prepared by bonding silica or ODS-silica particles together, by sintering or by embedding silica particles in a silica gel structure,... 

Fig. 5.1. Scanning electron micrographs of continuous-bed columns prepared from ODS-silica particles packed in a capillary. Prepared from (a) 75 pm capillary packed with silica particles by sintering in the presence of NaHC03 [9], and (b) large pore (left) and small-pore (right) ODS particles by a sol-gel method [10]. Reproduced from refs. 9 and 10, with permission.

Fig. 6.33. Scanning electron micrograph of a capillary column packed with 5 pm ODS silica beads and entrapped in porous poly(methyl methacrylate-co-ethylene dimethacrylate-co-2-acrylamido-2-methyl-l-propanesulfonic acid). (Reprinted with permission from [63]. Copyright 2000 American Chemical Society).

Figure 6.8 Experimental variation of the retention of 23 phenylthiohydantoin (PTH) derivatives of amino acids with mobile phase composition in RPLC. Mobile phase mixtures of acetonitrile and 0.05M aqueous sodium nitrate buffer (pH — 5.81). All mobile phases contain 3% THF. Stationary phase ODS silica. Solutes D = aspartic acid C-OH = cysteic acid E = glutamic acid N = asparagine S = serine T = threonine G = glycine H = histidine Q = glutamine R = arginine A = alanine METS = methionine sulphone ABA = a-aminobutyric acid Y = tyrosine P = proline V = valine M = methionine NV = norvaline I = isoleucine F = phenylalanine L = leucine W = tryptophan K = lysine. Figure taken from ref. [610]. Reprinted with permission.

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