HPLC material compatibility

It is clear that CD measurements can provide unique information which can be used to design and optimize the separation of structurally complex, biologically active materials. However, the fact that HPLC is a time dependent experiment, and the time dependence of the analyte distribution is not compatible with the scanning rate of conventional CD instruments currently limits the CD-HPLC measurement to a single wavelength. This problem will be solved if multichannel detection can be effectively coupled to the CD experiment. 

Apart from the Chirasil-L-Val method, sarin enantiomers were also separated by a 2D-GC technique on chiral Cyclo-dex B material prior to NPD monitoring (Spruit et al., 2000, 2001). An additional GC-based approach allowed baseline separation of cyclosarin enantiomers on a GAMMA DEX column monitored by EI-MS (Reiter et al, 2007). VX enantiomers were chromatographed on a Chiracel OD column by LC coupled to an electrochemical detector yielding a lower limit of quantification of about lOng/ml blood (Van der Schans et al, 2003). To our knowledge no chiral HPLC-MS separation of OPCs has been described so far although mobile phases are compatible with MS detection. 

Because of the diversity of applications of modem liquid chromatography, there is no universal column packing material. StiU, a more or less ideal HPLC packing should be inert toward analytes, pH stable, and compatible with both nonpolar and polar organic solvents and even water, and allow fast diffusion of analytes in the interior of the sorbent bead. These conditions are best met by the new, third generation of polymeric adsorbent materials, hypercrosslinked polystyrenes. A rigid open-work-type hypercrosslinked network displays extremely high apparent specific surface area (up to... 

Alternatively, antibodies can be used as chemically-selective detectors following HPLC separation of material fix>m a complex mixture of chemicals. HPLC/Immunoassay (HPLC/IA) in some cases offers a 1,000-fold increase in sensitivity over (HPLC/UV), and the selectivity to quantify compounds present as only trace fractions of the total. One current liinitation of ] LC is that there is no on-line iimnuno-detector allowing real time immunochemical sensing of the column effluent Rather, fractions must collected, the solvent exchanged to be compatible with the antibodies, and immunoassays run on the individual fractions from the HPLC. The automated, parallel process nature of immunoassays means that it is relatively simple to assay up to 100 fractions from a chromatogram. In spite of the... 

O-ring seals are less common in HPLC columns, but are quite feanUe. The main issue is the compatibility of the O-ring material with the mobile phase. Incompatible O-rings can disintegrate resulting in a sudden loss of the seal O-rings made of fluorocarbon-based rubbers such as Kalrez or Chemraz have a suffidently broad solvent compatibility to be useful with all molnle phases commonly used in HPLC. 

Up to now, we have entirely ignored the solvent that is used to displace the slurry in the slurry reservoir. Ideally, the solvent used to prepare the slurry should also be used to displace the slurry. However, there are some practical limitations for instance, the materials of construction in the pump may not be compatible with the slurry solvent. This is not an issue if HPLC pumps are used, but is of serious concern for air-driven pumps that may use elastomeric seals, which usually have a limited solvent compatibility. In tl case a different solvent needs to be chosen to push the slurry into the column. This solvent has several different requirements to fulfill ... 

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