INDEX Zorbax

Chromatographic conditions elution with 50 50 methanol/water solvent at the rate of 1.5 ml,/min through a DuPont Zorbax ODS column using a Waters R-401 Refractive Index Detector. 

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... 

Refractive Index Detector (Knauer). The KMX-6 scattering intensity was measured with the 6-7 degree forward-scattering annulus. A series of Zorbax PSM columns (DuPont) was used PSM 60, PSM 1000, PSM 1000, PSM 60, PSM 1000. Tetrahydrofuran (THF) from Baker was filtered through a 0.22 micrometer Fluoropore filter (Millipore Corp.) before use in chromatography, and a flow rate of 0.7 ml/min was used. 

Gel Permeation Chromatography. A Waters (model 150-C ALC/GPC) liquid chromatograph with a refractive index detector was used for molecular weight characterization. The unit was equipped with two sets of silanized Dupont blmodcLl columns (Zorbax PSM 60S/100S), with molecular weight range 2 x 10z to 10° and total retention volume of 24 ml. Samples were cut across the plaque thickness as with DSC. Polymer solutions were prepared 1n N,N -dimethyl -formamide, DMF, at 0.1%... 

HPLC, using a reversed phase system consisting of a Zorbax NH2 column eluted with acetonitrile/water (4 1), was employed for the preparative separation of the calystegines [10], The lack of a chromophore renders the use of UV or fluorescence detection impossible without pre- or post-derivatization of the sample and the relatively low sensitivity of refractive index (RI) detection severely limits this technique for routine analysis. However, the rapid evolution of LC-MS methods may lead to their application in the future. 

The CD formed in the reaction mixture was detected by HPLC. Conditions for HPLC were based on that described by Sato et al. (24). The HPLC system consisted of Jasco PU 990 pump (Jasco, Japan) connected to a Shodex R1 72 refiactive index detector. In this system, it was connected a Zorbax-NH2 column (250x4.6 mm, 5 (im, Aligent Technologies) installed in a eolumn oven Dionex STH 585 (Dionex Softron GmbH, Germany) at 35 °C. It was used a mixture of acetonitrile/water (65 35 v/v) with the flow rate of 0.8 mL/min. All experiments were done in triplicate. 

Gel permeation chromatograms were obtained using an HPLC Waters 244 Instrument with Zorbax PSM 1000-COS columns and a differential refractive index detector. A 0.25 wt% solution in chloroform solvent was used with a flow of 0.5 ml/min. 

The separation of a-olefin sulphonates into their hydroxy, alkene, and disulphonate isomers together with chain length information is described in [24]. A column (25 cm x 4.6 mm) of Zorbax TMS is used with a mobile phase of methanol/water (75 25, v/v) and refractive index detection. Equivalent columns and conditions were used in [25] with the major difference of an operating temperature of 55°C. 

Ci4 and Ci6 a-olefin sulfonates separation by alkyl chain length separation of alkenesulfonate from hydroxyalkanesulfonate isomer separation Reversed-phase Dupont Zorbax TMS, 4.6 X 250 mm 75 25 MeOH/HzO, 0.4 M NaNO, Refractive index 55... 

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