Separator Atlantis

We turn our attention now to the hydrothermal brines of the Red Sea. An oceanic survey in 1963 discovered pools of hot, saline, and metal-rich brines along the axial rift of the Red Sea (Degens and Ross, 1969 Hoffmann, 1991). The dense brines pond in the rift s depressions, or deeps. The Atlantis II deep contains the largest pool, which measures 5 x 14 km and holds about 5 km3 of supersaline brine. The deep holds two layers of brine. The lower brine contains about 25 wt.% dissolved salts and exists at temperatures up to 60 °C. Table 6.8 shows the brine s average composition. A somewhat cooler, less saline water overlies the lower brine, separating it from normal seawater. 

The extract was filtered through a 0.2 fim MilliQ filter and chromatographically separated using an Atlantis Cig, 5 /un, 19 mm x 150 mm column, 10 mL min (4—8 % of MeCN in 5 him ammonium acetate, pH 5.0). Glucuroconjugated metabolite peak fractions were collected and the mobile phase was removed by lyophihzation. The products were weighed and reconstituted either in CD3OD to perform NMR analysis or in 100 % methanol and stored at —80 °C. 

FIGURE 6.16 Separation of 1 = phenol 2 = 2-naphthalene sulfonic acid 3 = p-xylenesulfonic acid 4 = caffeine 5 = nortriptyline 6 = diphenhydramine 7 = benzylamine 8 = procainamide on Atlantis silica column (25 x 0.46 cm, 5 xm particles). Mobile phase acetonitrile-0.1 M ammonium formate pH 3.0 (85 15, v/v), 1 mLmin b... 

FIGURE 16 Comparison of a HILIC separation (top) and a reversed-phase separation (bottom). Peak I morphine, peak 2 morphine 3- glucuronide.Top column Atlantis HILIC Silica, 4.6x50mm, 3.0 lm gradient from 90% to 50% acetonitrile with lOmM ammonium formate buffer, pH 3.0 flow rate 2.0mL/min. Bottom Atlantis dC g, 4.6x50mm, 3.0pm mobile phase 2% acetonitrile with lOmM ammonium formate buffer, pH 3.0 flow rate l.4mL/min. 

A selective, sensitive, and rapid hydrophilic interaction liquid chromatography with electrospray ionization tandem mass spectrometry was developed for the determination of donepezil in human plasma [32], Donepezil was twice extracted from human plasma using methyl-ferf-butyl ether at basic pH. The analytes were separated on an Atlantis HILIC Silica column with the mobile phase of acetonitrile ammonium formate (50 mM, pH 4.0) (85 15, v/v) and detected by tandem mass spectrometry in the selective reaction monitoring mode. The calibration curve was linear (r = 0.9994) over the concentration range of 0.10-50.0 ng/ ml and the lower limit of quantification was 0.1 ng/ml using 200 /d plasma sample. The CV and relative error for intra- and inter-assay at four quality control levels were 2.7% to 10.5% and —10.0% to 0.0%, respectively. There was no matrix effect for donepezil and cisapride. The present method was successfully applied to the pharmacokinetic study of donepezil after oral dose of donepezil hydrochloride (10 mg tablet) to male healthy volunteers. 

Figure 14-6. Separation of pyridine-related compounds by HILIC. Chromatographic conditions Atlantis HILIC silica 3 pm, 150 x 4.6 mm. Mobile phase A 0.1 % phosphoric acid in D.I water. Mobile phase B Acetonitrile. Gradient at 95% B to 60% B in 7 min and then hold 8 min.

In preliminary tests, four ODS Qg columns with different colunm size and/or different particle size were compared regarding the separation of the four vitamins and methotrexate internal standard. Column A is a Waters Atlantis Cj column (150 X 2.1 mm i.d., 5 pm particle size), column B is a Waters Sunfire Cj column (150 X 2.1 mm i.d., 5 pm particle size), column C is a Waters Acquity UPLC BEH Cj column (50 x 2.1 mm i.d., 1.7 pm particle size), and column D is a Waters Acquity UPLC BEH C18 column (100 x 2.1 mm i.d., 1.7 pm particle size). 

Jastrebova and his coworkers compared both UPLC and HPLC for the separation and determination of the most common dietary folates (a group of derivatives of folic acid) 5-methyltetrahydrofolate (5-CH3-H4folate), tetrahydrofolate (H4folate), 5-formyltetrahydrofolate (5-HCO-H4folate), 10-formylfolic acid (lO-HCO-folic acid), and folic acid [95], Four alkyl-bonded columns, two UPLC columns—Acquity BEH C,8 and Acquity HSS T3, 100 x 2.1 mm i.d 1.7 pm particle size—and two HPLC columns— Xbridge C,g and Atlantis dl8, 150 x 4.6 mm i.d., 3.5 pm particle size— were tested for this purpose. In respect to the surface chemistry, the Acquity BEH C18 column is similar to the XBridge Cj8 column, while the Acquity HSS T3 column is similar to the Atlantis dl8 column. 

If polar and apolar interactions are necessary for separation (e.g., components with amino and acidic groups), phases may be encountered that show sufficient hydrophobicity but which are also capable of polar interactions because of additional polar groups on the surface, e.g., Spherisorb ODS 2, LiChrospher, Polaris C18-A, Ascends RP-Amide, Purosphere, Uptisphere UP5MM, Nucleodur Sphinx RP, Atlantis d Cjg, SynergiFUSION RP, and Acclaim PA. The fine adjusting for a better selectivity can be most effectively achieved by means of the pH of the eluent and by variation of the acid/base used [8]. A possible lack of robustness of the method has to be accepted in such systems. 

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