ODS column

The enantiomeric excess of 3.10c has been determined by HPLC analysis using a Daicel Chiracel OD column and eluting with a 60 / 1 (v/v) hexane(HPLC-grade) / 2-propanol(p.a.) mixture. At a flow of 1 ml per minute the rentention times for the different isomers of 3.10c were 6.3 min. (exo, major enantiomer) 7.1 min. (exo, minor enantiomer) 7.7 min. (endo, major enantiomer) 10.7 min. (endo, minor enantiomer). 

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. 

HPLC analysis of anatoxin-a was first carried out by Astrachan and Archer, " who extracted the toxin from Anabaenaflos-aquae using chloroform followed by hydrochloric acid. The HPLC analysis was carried out on an ODS column using hypochlorate-methanol. Other systems used since include acetic acid extraction and analysis on a reversed-phase C g column using methanol-water mobile phase, and extraction in water after ultrasonication and analysis on reversed-phase... 

Dibenzyl-14-crown-4 (lithium ionophore VI 6,6-dibenzyl-l,4,8,ll-tetra-oxa-cyclo-tetradecane) [106868-21-7] M 384.5, m 102-103°. Dissolve in CHCI3, wash with saturated aqueous NaCl, dry with MgSOa, evaporate and purify by chromatography on silica gel and gradient elution with C6Hg-MeOH followed by preparative reverse phase HPLC on an octadecyl silanised silica (ODS) column and eluting with MeOH. It can be crystd from MeOH (v Br 120 cm , C-O-C). [7 Chem Soc Perkin Trans 1 1945 1986.]... 

FIGURE 4.22 HPLC chromatogram of amino acids employing precolumn derivatiza-tion with OPA. Chromatography was carried out on an Ultrasphere ODS column using a complex tetrahydrofuran methanol 0.05 M sodium acetate (pH 5.9) 1 19 80 to methanol 0.05 M sodium acetate (pH 5.9) 4 1 gradient at a flow rate of 1.7 mL/min. 

The submitters report obtaining the product in 99% yield. The enantiomeric excess of the Mosher ester of 3 was measured to be 98% using a Chiralcel OD column (40% 2-propanol/hexane). This optical purity measurement substantiated the optical purity assessment made by 111 NMR studies of 3 and racemic 3 prepared using a different method3. Addition of the chiral shift reagent tris[3-(heptafluoropropylhydroxymethylene)-(+)-camphorato]europium (III) resulted in clear resolution of the respective aromatic proton signals for the two enantiomers, which was demonstrated with the racemate. Under similar conditions, NMR analysis of 3 showed that within the detectable limits of the experiment (ca. <3%), there was none of the disfavored enantiomer. 

Quantitative HPLC analysis was carried out on a Spectraphysics 8720 chromatography system, a rapid scan detector by Barspec on a Zorbax ODS column with acetonitrile water 75/25 as the eluent. 

Assay of Endogenous NE. Endogenous NE release from the guinea pig vas deferens was measured by means of a high pressure-liquid chromatograph with an ODS column and an electrochemical detector as described previously (16). 

Similarly to the methods used to characterize natural chlorophylls, RP-HPLC has been chosen by several authors to identify the individual components in Cn chlorophyllin preparations and in foods. The same ODS columns, mobile phase and ion pairing or ion suppressing techniques coupled to online photodiode UV-Vis and/or fluorescence detectors have been used. ° ... 

Valko et al. [37] developed a fast-gradient RP-HPLC method for the determination of a chromatographic hydrophobicity index (CHI). An octadecylsilane (ODS) column and 50 mM aqueous ammonium acetate (pH 7.4) mobile phase with acetonitrile as an organic modifier (0-100%) were used. The system calibration and quality control were performed periodically by measuring retention for 10 standards unionized at pH 7.4. The CHI could then be used as an independent measure of hydrophobicity. In addition, its correlation with linear free-energy parameters explained some molecular descriptors, including H-bond basicity/ acidity and dipolarity/polarizability. It is noted [27] that there are significant differences between CHI values and octanol-water log D values. 

Typical operating conditions by GC and HPLC are listed in Tables 2 and 3, respectively. Anilides are separated using a weakly polar liquid-phase capillary column, such as SPB-1 or HP-5, which is prepared based on 5% diphenyl-95% dimethylpolysilox-ane for GC. For HPLC, ODS columns are used. 

Since the methyl ester of prohexadione had lower polarity compared with prohexadione, an ODS column was very useful for purifying the sample. 

HPLC) system equipped with an ODS column and ultraviolet (UV) detector for quantitative determination. 

The analysis of amino acids involves chromatographic issues similar to those encountered in analysis of simple amines. Underivatized amino acids have, with a few exceptions, weak UV absorbance and a strong tendency to interact with stationary phases in undesirable ways. Underivatized amino acids are normally separated with ion exchange chromatography, then visualized post-column by reaction with ninhydrin, o-phthaladehyde (OPA), or other agents. Underivatized tryptophan and the metabolites kynurenine, 3-hydroxykynurenine, kynurenic acid, and 3-hydroxyanthranilic acid, were separated on a Partisphere 5-p ODS column with fluorescent detection.121... 

Ito, K. and Kumamaru, T., Separation and detection of common mono- and divalent cations by ion chromatography with an ODS column and conduc-tivity/UV detection, /. Chromatogr. A, 850, 247, 1999. 

Eleven zinc dialkyldithiophosphates (ZDDPs) in lubricating oil additives were separated by NPLC [723] eight ZDDPs were separated on an ODS column... 

Achiral-chiral chromatography has also been accomplished using subcritical fluid chromatography (Phinney et al., 1998). In this work, the structurally related [3-blockers, 1,4-benzodiazepines, and two cold medicines were separated using methanol or ethanol modified carbon dioxide mobile phases. The (3-blockers were separated using cyanopropyl and Chiracel OD columns connected in series. Likewise, an amino bonded phase and Chiracel OD column were used for the separation of the 1,4-benzodiazepines. Guaifenesin and phenylpropanolamine from cough syrup were separated on cyanopropyl and Chiralpak AD columns in series. 

Fig. 12A-C Separation of Type II pheromone components by HPLC with an ODS column (4.6 mm ID X 25 cm) A a crude pheromone extract of Spilosoma imparilis (Arctiidae, 2 FE) including l,Z3,Z6,epo9-21 H (I),Z3,Z6,epo9-21 H (II),Z3,Z6,epo9-23 H (III),Z6,epo9-23 H (IV), and Z3,Z6,Z9-21 H (V) detected by UV 215 nm B a mixture of synthetic standards (ca. 1 pg each of II-V) detected by RID C the same synthetic mixture detected by UV 215 nm. The solvent system is 3.5% water in MeOH (1.0 ml/min)...

The separations of OTC have been carried out, in most instances, with reversed phase (RP) and polymeric ODS column. One difficulty in the analysis of OTC using RP-HPLC is the interaction of OTC with metal ions to form chelate complexes and the adsorption of OTC on RP columns, which consequently leads to severe peak... 

RP-HPLC-RT correlation, ODS column with masking agent, Bechalany et al. 1989)... 

HPLC-k correlation ODS column Diol column quoted lit. average, Helweg et al. 1997) 3.33 (range 3.24-3.40) (slow stirring method-HPLC/fluo., De Maagd et al. 1998)... 

---