Reversed-phase ODS column

A stability indicating HPLC method has been developed to measure etodolac in presence of three main degradants, 7-ethyl-2-( 1 -methylene-propyl)- 1 -//-indole-3 -ethanol, the decarboxylated product of etodolac, and 7-ethyltryptophol [23]. A reverse phase ODS column (15 cm x 0.41 cm i.d., 5 pm particles) was used to achieve separation. The mobile phase... 

The enzyme assay components including internal standards are resolved within 3 minutes on a 4.6 mm x 3.3 cm, 3 gm reversed-phase ODS column (Perkin-Elmer). The mobile phase contained 0.100 M citric acid, 0.50 mW tetrapentylammonium chloride (an ion-pairing agent), 50 fiM EDTA, and 12.5% acetonitrile (v/v) titrated to pH 4.70 with NaOH. Eluted compounds were detected with an electrochemical detector. The separation obtained is shown in Figure 9.16. 

Figure 21-2. Separation of 247 mg of epothilone A (first eluting) and B (structure given below) on a semipreparative reversed-phase ODS column (25-cm x 2.0-cm i.d.). Particle size ll xm, mobile phase acetonitrile/water = 4/6 (V/V), flow rate 15mL/min, UV detection 250 nm.

Whole plants of Scoparia dulcis collected in Paraguay were extracted with 70% EtOH at boiling temperature. The extract was partitioned between CHC13 and H2O and the CHC13 soluble part was further fractionated by combination of column chromatography on silica gel and HPLC method using reversed phase ODS column. As a result, three types of diterpenoids were isolated, i.e., labdane-type scoparic acids A (SA, 1), B (SB, 2), and C (SC, 3), scopadulan-type scopadulcic acids A (SDA, 4) and B (SDB, 5), and aphidicolan-type scopadulin (SD, 6). On the other hand, scopadiol... 

An electrostatic ion chromatographic method was developed for the direct determination of iodide, bromide and nitrate in seawater (Hu et ai, 1999). An octadecylsifica column modified with a zwitterionic surfactant 3- NJV-dimethylmyristylammonio)propane-suifonate was used as the stationary phase, and an electrolytic solution was used as the eluent. The matrix species (such as chloride and sulfate) were retained weakly, and showed iitde or no interference. The method was applied to the determination of iodide, bromide, and nitrate in artificial seawater, giving detection fimits of 0.8 p,g 1 for iodide, 0.75 p.g 1 for bromide, and 0.52 p,g 1 for nitrate, and relative standard deviations of <1.2%. The real seawater samples were also analyzed successfully. Later, another electrostatic ion chromatographic method was developed for the determination of iodide in seawater by the same research group (Hu et ai, 2002). A reversed-phase ODS column was... 

Walter s White corn plants were grown until the silks had dried. The leaves were processed and extracted in a fashion similar to teosinte. The crude extract, however, was deposited directly onto silica gel, eluted from a silica gel column as with the teosinte extract and then further purified on an open reversed phase ODS column. Luteolin glycosides were obtained in 30-50% methanohwater fractions. Further purification of small amounts for FAB-MS was achieved by thin-layer chromatography using aluminum backed silica gel plates (Whatman cat. 4420 222) with EtOAc MEK formic acid water, 5 3 1 1 as developing solvent. The compounds in the scraped bands were eluted with methanol. 

Recently, a validated LC method was reported for the separation of the structural (metalpara) isomers of fexofenadine hydrochloride with a chiral mobile phase [19]. This is an interesting example in which an achiral reversed-phase ODS column is used for the separation of enantiomers in chiral combination with the mobile phase, pH 3 aqueous buffer-MeCN (60 40), containing 5 gfL P-cyclodextrin as a chiral additive. 

An important work on the LC-APPI-MS/MS field was developed for the analysis of 12 PAHs in sediment samples (Moriwaki et al. 2004). In this context APPI was performed in positive mode aiming to overcome the low sensitivity of poor fluorescence PAHs. Extraction of PAHs from sediments was conducted with ultrasonic agitation and the mixture was purified on a silica cartridge. PAHs were eluted with a mixture of hexane toluene (9 1) and separated on a reversed phase ODS column with a runtime of 20 min. From mass spectrometry point of view the positive molecular ions were observed as the main peaks for all PAHs. Limits of determination ranged from 6 to 91 ng/g thus they were comparable with LODs presented in HPLC-FLD analyses. The method had also acceptable recovery values (90-116%). 

HPLC condition — A Waters reversed-phase HPLC column (Symmetry Shield RP Cl8, 5 pm, 2.1 x 50 mm) was used in conjunction with a Regis SPS guard column (ODS, 5 pm, 100 A,... 

An isocratic HPLC method for screening plasma samples for sixteen different non-steroidal anti-inflammatory drugs (including etodolac) has been developed [29]. The extraction efficiency from plasma was 98%. Plasma samples (100-500 pL) were spiked with internal standard (benzoyl-4-phenyl)-2-butyric acid and 1 M HC1 and were extracted with diethyl ether. The organic phase was separated, evaporated, the dry residue reconstituted in mobile phase (acetonitrile-0.3% acetic acid-tetrahydrofuran, in a 36 63.1 0,9 v/v ratio), and injected on a reverse-phase ODS 300 x 3.9 mm i.d. column heated to 40°C. A flow rate of 1 mL/min was used, and UV detection at 254 nm was used for quantitation. The retention time of etodolac was 30.0 minutes. The assay was found to be linear over the range of 0.2 to 100 pg/mL, with a limit of detection of 0.1 pg/mL. The coefficients of variation for precision and reproducibility were 2.9% and 6.0%, respectively. Less than 1% variability for intra-day, and less than 5% for inter-day, in retention times was obtained. The effect of various factors, such as, different organic solvents for extraction, pH of mobile phase, proportion of acetonitrile and THF in mobile phase, column temperature, and different detection wavelengths on the extraction and separation of analytes was studied. 

The reactant was separated from the product as the fluorescamine derivatives on a reversed-phase HPLC column (Partisil ODS) and eluted isocratically using a two-solvent system. To elute the dipeptide, the solvent was 60% acetonitrile in water diluted 9 1 with 1 M acetic acid, at a final pH of 3.5 (Fig. 9.24). To elute the angiotensin compounds, 38% acetonitrile in 1 M ammonium acetate (pH 4.0) was used (Fig. 9.25). The eluent was monitored with a fluorometer. 

An artificial substrate labeled with a strong UV-absorbing chromophore was synthesized. This substrate and its product, obtained by hydrolysis of the ADP-ribosyl moiety, were separated on a Zorbax-ODS reversed-phase CI8 column (4.6 mm X 250 mm). The initial mobile phase was 70% 0.0435 M sodium acetate (pH 4.0) and 30% acetonitrile. The percentage of acetonitrile... 

Guard column 50 x 5 40 p-m Waters reverse-phase guard column material Column 100 x 5 5 p,m Hypersil 5-ODS... 

Permaphase ODS, 1 m X 2.1 mm I.D., reversed-phase partition column with octadecylsilane as stationary phase, chemically bonded to a controlled porous surface ( porosity beads , 20-37 pm) by means of Si-O-Si bonds and contains about 1% stationary phase. Pre-packed Permaphase ODS column has 600 theoretical plates, determined by isocratic elution of anthracene with methanol-water (6 4)... 

Figure 6 Chromatogram of water-soluble vitamins from standard solution. Ion pair chromatography with a reversed-phase Cig column (Tracer Spherisorb ODS 2, 250 X 4.6 mm i.d., 5 pm) UV detection at different wavelengths mobile phase (1 mL/min) contained octanesulfonic acid (5 mM), triethylamine (0.5%), glacial acetic acid (2.4%), and methanol (15%) at pH 3.6. Peak identities (1) nicotinamide (2) pyridoxal (3) pyridoxine (4) pyridoxamine (5) folic acid (6) riboflavin (7) cyanocobalamin (8) thiamin. (From Ref. 94.)...

HPLC analysis can replace the spectrophotometric determination The sample preparation follows Procedure 1, above, except that NaOH is not added when the hexane extract is evaporated. The residue after evaporation is dissolved in 5 mL of the HPLC mobile phase A. The separation is performed on a reversed-phase Cjg column such as Shandon ODS or Whatman Partisil 5 ODS 3,4.6 x 250 mm. A mobile phase gradient is used, where solution A is water, 0.1 M in NaC104, and solution B is 70 30 acetonitrile/water, both 0.1 M in NaC104. The gradient is formed from 70% B to 90% B in 25 min. Detection is by UV absorbance at 225 nm. 

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 13.9 Coupled-column RPLC-UV (215 nm) analysis of 100 p.1 of an extract of a spiked soil sample (fenpropimoiph, 0.052 mg Kg ). LC conditions C-1, 5 p.m Hypersil SAS (60 m X 4.6 mm i.d.) C-2, 5 p.m Hypersil ODS (150 m X 4.6 mm i.d.) M-1, acetonitrile-0.5 % ammonia in water (50 50, v/v) M-2, acetonitrile-0.5 % ammonia in water (90 10, v/v) flow-rate, 1 ml min clean-up volume, 5.9 ml transfer volume, 0.45 ml. The dashed line represents the cliromatogram obtained when using the two columns connected in series without column switcliing. Reprinted from Journal of Chromatography A, 703, E. A. Hogendoom and R van Zoonen, Coupled-column reversed-phase liquid cliromatography in envir onmental analysis , pp. 149-166, copyright 1995, with permission from Elsevier Science.

Polymer C18 Column ODS-A 120A Silica Based Reverse Phase Column... 

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