Separator Zorbax

The mechanism of separation is the same for Zorbax PSM columns as it is for other types of SEC columns. As the mobile phase flows through the column, large molecules are forced down the column at faster rates than small molecules because the large molecules have less access to the column volume inside the pores. Consequently, molecules that are too large to permeate any of the pore... 

Zorbax PSM Bimodal and Trimodal columns are packed with mixed pore-size packing to achieve linear size separations over a broad molecular weight range (Table 3.3). Zorbax PSM Bimodal columns are packed with PSM 60 and PSM 1000 particles, and Trimodal columns contain PSM 60, PSM 300, and PSM 3000 particles (Fig. 3.4). Carefully selecting and mixing different pore-size particles in columns provide much better linearity than coupling columns that are each packed with single pore-size particles. 

The size separation of proteins has been routinely called gel filtration because of the historic use of cross-linked gels for this application. Specially modified Zorbax PSM columns, Zorbax GF-250 and Zorbax GE-450, are used for separating proteins by size. These columns are packed with porous silica micro-... 

Proteins are separated on Zorbax GF columns based on their hydrodynamic size, which may be related to the proteins molecular weights (Fig. 3.10). Under ideal conditions, two proteins whose molecular sizes differ by a factor of 2 can be baseline separated. 

Zorbax GF columns can be used for size-separation applications such as estimating molecular weight purifying complex mixtures monitoring reac-... 

FIGURE 3.10 Under ideal conditions, proteins are separated on Zorbax GF columns based on their hydrodynamic size. 

As with other size-exclusion techniques, the pore size of the selected Zorbax GF column should provide resolution over the molecular size range of the proteins that are to be separated. The Zorbax GF-250 column separates proteins in the range of 4000 to 400,000 Da. The Zorbax GF-450 provides separation over the range of 10,000 to 1,000,000 Da. When these two columns are coupled, they can be used to separate proteins with molecular weights of 4000 to 1,000,000. 

Figure 1.16 Separation ot a test mixture by adsorption chromatography on a 1 m x 1 mm I.D. small bore column packed with 8 aicrometer Zorbax B.P. Sil operated at a flow rate of ISO microliters/min (left) and a 22 m x 1 mm I.D. column of the same packing material prepared by series coupling of 1 m segments and operated at a flow rate of 15 microliters/min (right). (Reproduced with permission from ref. 234. Copyright American Chemical Society).

Diiren, Germany) BTR Separations (Wilmington, DE) Zorbax Pro 10/60 CN Alkyl cyano phase on silica 10 p, 60 A ... 

Detectability may be a significant problem with homologous series of unsaturated compounds, particularly //-alkanes. For these compounds, refractive index detection or evaporative light-scattering, both of which are described elsewhere in the book, may be of use. Indirect photometry is a useful detection scheme for compounds that do not absorb in the UV. Acetone, methylethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, and acetophenone are added to an acetonitrile/water mobile phase, generating a negative vacancy peak when the nonchro-mophoric analyte emerges and a positive peak if the ketone is adsorbed and displaced.70 Dodecyl, tetradecyl, cetyl, and stearyl alcohols also have been derivatized with 2-(4-carboxyphenyl)-5,6-dimethylbenzimidazole and the derivatives separated on Zorbax ODS in a mobile phase of methanol and 2-propanol.71... 

Figure 14 Separation of 1,2/1,4 ketal with and without protection from oxidative degradation. Chromatographic conditions were column 25 cm x 4.6 mm Zorbax C8 (5-pm) column mobile phase 100 mM KH2P04 (pH 6.5) acetonitrile (50 50) flow rate 1.0 ml/min column temperature 35°C detector wavelength 220 nm. (A) Acetonitrile degassed. (B) Acetonitrile not degassed.

Chromatographic Separations and Implications. Fractionation of hydrilla-inhibiting extracts has perhaps produced the most interesting results concerning the basis for hydrilla inhibition. Two fractions were generated, and best results were obtained with an older, preparative-scale Zorbax column. The effect of both fractions on hydrilla was tested using Warburg apparatus the first fraction did not affect either plant respiration or photosynthesis. The... 

LC-MS-MS was also the method of choice for the analysis of UV filters in solid matrices. Both LC and UPLC have been applied in three out of the four methods available for the determination of UV filters in sludge. Separation was performed on C8 and C18 LC-chromatographic columns (Zorbax, Eclipse, Vydac, and Purosphere) using binary gradient elution of mobile phases consisting of water/ methanol or water/acetonitrile. MS-MS detection was performed in SRM with ESI and atmospheric pressure photoionization (APPI) in both positive and negative modes. For each compound, two characteristics transitions were monitored. In addition to MS and MS-MS, diode array detection (DAD) was occasionally applied to the determination of OT. Spectra were recorded between 240 and 360 nm and discrete channels at 310 nm. 

Axelsen and Vogelsang have reported the separation of gramicidins A, B and C by HPLC using Zorbax ODS (5 pm) eluted at 60 C with methanol-5 mM ammonium sulfate (37 13) 200. ... 

Figure 4.13 Separation of the tryptic peptides from recombinant HGH using a 120-min linear gradient at 60°C from water + 0.1% TFA to 40 60 water acetonitrile + 0.1% TFA. Column Zorbax SB-C8, 4.6 X 150 mm, 30-nm pore, 5- tm particle size. (Reprinted from W.S. Hancock, R.C. Chloupek, J.J. Kirkland, and L.R. Snyder, J. Chromatogr. A, 686 31 [1994]. With permission from Elsevier Science.)...

NP chromatography is unable to separate vitamin D2 from vitamin Dj. So it is usually used as semipreparative chromatography [527-531]. Instead, RP chromatography is able to resolve vitamin D2 and Dj, thus it is widely applied as aualy tical chromatography. Mattila et al. [532] describe a two dimensioual LC procedure. The sample is saponified and an NP semipreparative column is used before the quantification in a tandem column set (Zorbax ODS x Vydac 201 TP54 CIS). 

Figure 3. Standards recovered from 10 mL of distilled-deionized water on an ODS precolumn. Peak identities 4, 0.14 pg of caffeine 5, 0.20 pg of pentachlorophenol 7, 0.061 pg of m-nitroandine 8, 0.15 pg of atrazine 9, 0.40 pg of quinoline 10, 0.26 pg of 2,6-dichloroaniline 11, 0.14 pg of N-nitrosodiphenylamine and 12, 0.055 pg of pyrene. Conditions for concentration 10-mL sample enriched on an ODS-packed precolumn. Analytical separation was on Zorbax ODS, 250-mm by 4.6-mm i.d. column. Mobile-phase gradient was 100% pH 7,0.1 M acetate buffer for 2 min followed by ramp to 90% acetonitrile/10% pH 7, 0.1 M acetate buffer (v/v) in 20 min at 1.0-mL/min flow rate. Detection was at 254 nm. (Reproduced with permission from reference 18.)...

High-Performance Liquid Chromatography. A Varian 5060 delivery system was used for this work with detection by UV absorption. Either a Varian UV-50 variable wavelength detector or a Hewlett Packard 1040A scanning diode array detector was used. All HPLC columns were packed in our laboratory (10) with 5-/um particle size Spherisorb-ODS, Spherisorb-CN (Phase Separations), or 8-pm particle size Zorbax-CN (Dupont Ltd). HPLC columns (20 or 25 cm X 4.6 mm i.d.) were coupled via short lengths of stainless steel capillary tubing (5 cm X 0.25 mm i.d.). Separation conditions were as follows ... 

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