Symmetry Shield

A six-port valve was used in both manual and semi-automated SPME interfaces and PEEK tubing used to connect the HPLC system to the SPME probe. A Cohesive HTLC 2300 with dual pumps along with a Sciex API 3000 mass spectrometer was used for LC/MS/MS and a Symmetry Shield RP-18 (5 ji, 50 x 2.1 mm) for HPLC. A quaternary pump with flow switching was used for desorption chamber flushing along with MS make-up flow and a binary pump for LC/MS/MS. Acetoni-trile/0.1% acetic acid in water (90 10, solvent B) and 10 90 acetonitrile/0.1% aqueous acetic acid (solvent A) were used, with 10% B for 0.5 min ramped to 90% B in 2 min and held at this concentration for 1.5 min before returning to 10% B for 1 min at a flow rate of 0.5 mL/min. 

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,... 

FIGURE 2.5 Separation of flavanoids on a classical RP and on a shielded phase. Columns Symmetry CIS symmetry shield RPIS (150x4.6mm). Mobile phase ACN/lOmM PO4 buffer pH 3, 30/70 v/v, 40°C. 

FIGURE 2.12 Influence of pH value on retention of basic analytes. Samples A,A-dimethyl aniline A-ethyl aniline. Column symmetry shield CIS mobile phase acetonitrile-20 mM phosphate buffers-water, 35-35-... 

FIGURE 2.18 Separation of polar and acidic solutes on a classical RP and on shield phases. Columns Symmetry C8 and symmetry shield C8. Mobile phases 20% ACN, 10% HjO, 70% lOmM phosphate buffer pH 3 (v-v-v). 30% MeOH, 70% lOmM phosphate buffer pH 3 (v-v). Samples 1, 4-hydroxyisophthalic acid 2, acetylic salicylic acid 3, salicylic acid 4, phenol 5. methylparaben 6, dimethylphthalate. 

High biotin content Symmetry Shield C18 (50mmx2.1mm, 3.5 pm) ... 

Low biotin content heart-cut system Symmetry Shield Cl 8 (50mmx2.1 mm, 3.5pm)xVydac218TP5215 (150mmx2mm, 3.5pm)... 

Carbovir, ranitidine, ondansetron, imipramine, amitriptyline, clomipramine Water symmetry shield RP-8, 3.5 pm Acetonitrile-100 mALTris, pH 9.0 (70 30) 330 mm x 50 pm i.d. 245 mm packed length... 

Figure 4-1. Effect of column type on selectivity. Mobile phase Low pH. (A) 0.1 v/v % TFA. (B) 0.1 v/v% TFA in MeCN. Linear gradient from 5% B to 80% B in 40min, 220nm. Temperature, 40°C flow rate, l.OmL/min column dimensions, 150 x 3.0mm particle sizes, 3.5 pm for Symmetry Shield and Atlantis and 3.0pm for YMC ODS AQ. (Courtesy of Markus Krummen, Novartis Pharmaceuticals.)...

Figure 8-51. HPLC separation of 5-aminomdazole (RT at 1.23 min) and 1-aminoindan (RT at 2.28min), 70% H2O 30% MeCN. Flow, 0.5mL/min Waters symmetry shield, 50 X 4.6 mm, 5 tm.

A reverse phase ion-pairing HPLC method was developed by the submitters for analysis. Chromatographic conditions A 10-pL sample (0.1 mg/mL in acetonitrile) is injected onto a suitable liquid chromatograph equipped with a Waters Symmetry Shield RP18 column, 250 x 4.6 mm, 5 pm particle size at 40°C with a mobile phase of 0.404 g/L heptanesulfonic acid, sodium salt -i- 0.1% phosphoric acid (Component A, pH 2.2) and acetonitrile (Component B) at a flow rate of 1.0 mL/min, programmed with a linear gradient from 95 5 A B (v/v) to 30 70 A B (v/v) over 20 min. Detection is achieved by UV at 300 nm. The retention time is approximately 10 min. 

Hot water and enzymatic extracts were analyzed by IP chromatography on a Waters Symmetry Shield RP8 column using water-methanol (99 1) mobile phases that contained different perfluorinated carboxylic acids as ion-pairing agents. 0.1% HFBA in the mobile phase allowed the separation and ICP-MS detection of >20 Se compounds in 70 min. 

Waters Symmetry-Shield RP 18, XTerra RP and MS Thermo Hypersil BDS C 18... 

HPLC Conditions Columns Reverse phase, and particularly CIS columns such as Waters Symmetry Shield RP18, are most frequently used (Li et ah, 2003 Soars et ah, 2002 Zhang et ah, 2002). 

HyPURITY advance Nucleosil nautilus Symmetry shield C18... 

Symmetry Shield Kromasil Zorbax SB C8 Ascentis HS F5 Nucleodur Ascentis Express... 

Fig. 3 HPLC chromatogram obtained from the TLC fraction containing 10-DAB III (D) as shown in Fig. 1. A 5 [jim Waters Symmetry Shield Cig column, 150 mm X 4.6 mm I.D. was used and eluted with the gradient of acetonitrile in double distilled water.

Figure 9 serves to demonstrate this equalizing of the stationary phases in the presence of buffers even for non-ionic analytes. In Fig. 9a, the separation of the isomers of nitroaniline on four rather different stationary phases with the help of an alkaline acetonitrile buffer is shown. Apart from small differences in the retention time, the separation of the three peaks looks rather similar on each of the four columns. Fig. 9b shows the separation of the nitroanilines on Symmetry Shield and on Zorbax Bonus in a methanol/water mixture. The chromatograms look absolutely different even an inversion of the elution order is observed. This means that to exploit the individual properties of the stationary phases in the realm of ultimate selectivity, one should dispense with buffers, which is not easy to realize in routine work, where reproducible retention times are required. Nevertheless, one should remember this in the case of orthogonal tests see below. These phenomena are observed even with simple, polar, non-ionizable analytes such as ketones (see Fig. 10). 

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