Zorbax Bonus

Salm et al.44 developed a high-throughput analytical method to measure cyclosporine in whole blood. They used a simple SPE procedure, followed by HPLC-MS/MS. An Agilent 1100 liquid chromatograph was coupled with an Agilent Zorbax Bonus C18 reversed-phase column (50 x 2.1 mm, 5 jt/rn particle size). The column temperature was maintained at 70°C in a column oven. The mobile phase consisted of 80% methanol and 20% 40mM ammonium acetate buffer (pH 5.1) delivered isocratically at a flow of 0.4 mL/min. D12 cyclosporine was the IS. 

Phenomenex Luna phenyl-hexyl Agilent Zorbax Bonus RP and Extend C18 YMC Pro C 18... 

Finally, other highly polar phases can be thought of such as various fluorinated phases, Zorbax Bonus RP, or Synergi POLAR RP. 

Better resolution is achieved, especially in the first part of the chromatogram. The last apolar peak is slightly delayed by the polar CN material, but this small increase in run time is a price worth paying. Moreover, we have been able to separate tricyclic antidepressants and their metabolites (a total of 12 peaks) in one isocratic run using Zorbax Bonus/Chromolith Performance and AQUA/ Zorbax Extend coupled in series. 

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). 

Classical coverage/embedded phases (Zorbax Bonus plus steric protection)... 

In the case of pure RP interactions (e.g., a difference of only an additional CH2 group, methylene group selectivity ), the stationary phase is largely unimportant. The choice of the column is of secondary importance. Therefore, one obtains only a small difference in the separation factors between Zorbax Bonus and Zorbax Extend, which are two completely different phases. If the analyte has polar groups, as in the case of hydroxybenzoates, a differentiation of columns is more easily possible and the separation factors cover a wider range. In the case of triphenylene/o-terphenyl (additional steric effect), the range is even wider. If the polar phase can display its capacity for polar interactions, a better selectivity is observed in all cases. If the difference is only a shorter alkyl chain, as in the case of Zorbax SB Cg, then no distinct positive influences are observed. 

Zorbax Bonus is a more hydrophobic embedded phase than HyPURlTY ADVANCE. 

Zorbax Bonus is more hydrophobic than Nucleosil Nautilus, and this in turn is more hydrophobic than Prontosil ACE. The most polar embedded phase with a long alkyl chain is Symmetry Shield, with carbamate as the embedded polar group. 

Spherisorb ODSl Nucleosil Protectl SupelcosU ABZ PLUS Zorbax SB Cg Zorbax Bonus... 

Zorbax SB Cjg/300, Zorbax Edipse XDB, Zorbax ODS, Zorbax SB Cg, Zorbax Bonus (Zorbax SB AQ, in alkaline pH Zorbax Extend)... 

Zorbax SB 300 (Nucleodur CIS Gravity) Reprosil AQ Zorbax Bonus Fluofix INW... 

Figure 1.3 Exain)le of the influence of the data acquisition rate on peak distortion. The filter time is 0.1 s. Conditions Zorbax Bonus RP 100 x 2.1 mm, 1.8 p,m mobile phase A 0.1% TFA water mobile phase B acetonitrile gradient 20% -56% B for 2.06 min flow rate 0.8 mL/min wavelength 268 nm. Peaks 1 and 2 are impurities.

---