Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Reexamination Certificate
2000-02-08
2003-11-04
Warden, Jill (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
C422S068100, C422S081000, C422S082000, C436S043000, C210S656000, C210S659000
Reexamination Certificate
active
06641783
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a high efficiency chromatographic system. More specifically, the present invention relates to a chromatographic system for determining the physicochemical properties of one or more compounds using at least two chromatographic units in eluent flow communication with one eluent analyzer via an intermediate eluent switch.
BACKGROUND AND SUMMARY OF THE INVENTION
The emergence of automated chemical synthesis platforms coupled with combinatorial techniques as a routine tool in the pharmaceutical industry has enabled the synthesis of large numbers of molecules in a relatively short time. Millions of potential new drug candidates are created every year, and both pharmaceutical and biotechnology industries have embraced the challenge in recent years of developing new, faster and more efficient ways to screen pharmaceutical compounds in order to rapidly identify “hits” and develop them into promising lead candidates. This has created the need for high-throughput analytical approaches to characterize the synthesized compounds and has prompted the development of chromatographic systems specifically designed for the automated high-throughput identification, purity assessment or purification of combinatorial libraries.
Currently, automated, semi-quantitative assessment of combinatorial libraries is most readily accomplished by coupling HPLC with UV detection and mass spectrometry. Rapid HPLC methods with columns capable of delivering high-resolution separations have been developed in recent years, and have been well received by the drug discovery industry as a powerful tool particularly suited to handle the expanding analytical needs of combinatorial chemistry. The ability to characterize chemical libraries derived from combinatorial synthesis has in turn revealed that the purity of the compounds generated by this method is not necessarily high enough for biological evaluation of these compounds. Consequently, the scope of the high-throughput HPLC techniques initially designed and developed for structure confirmation purposes has expanded to include purity assessment and purification of the compound libraries to make them suitable for biological screening.
The technological advances directed toward the implementation of fast and high volume chromatographic systems have rapidly converged toward automated systems to accommodate the large number of compounds typically produced by most parallel syntheses nitially, automated preparative HPLC systems were designed so as to incorporate a fraction collection device activated upon detection of a threshold UV signal operating in conjunction with a secondary analytical unit (e.g., flow injection MS HPLC-ESI-MS) for the identification of the collected fractions. Recently, Kassel et al. (Zeng L., Burton L., Yung K., Shushan B., Kassel D. B., “Automated Analytical/Preparative High-Performance Liquid Chromnatography-Mass Spectrometry System for the Rapid Characterization and Purification of Compound Libraries”,
J. Chrom. A
, 794, 3-13, (1998)) added a major improvement to the technology by incorporating a “specific-mass-based” fraction collection device: fraction collection is initiated upon a real-time threshold reconstructed ion current signal being observed for a particular m/z input value, which corresponds to the mass of the compound being purified. This eliminates the need for post-purification screening and pooling required to identify the purified fractions of interest. Finally, they developed the system further and conceived an improved version of it (“Development of a Fully Automated HPLC/Mass Spectrometry System for the Analytical Characterization and Preparative Purification of Coinbinatorial Libraries”,
Anal. Chem
., 70(20), 4380-4388, (1998)). Kassel and coworkers devised an automated parallel analytical/preparative LC/MS system incorporating fast reversed-phase HPLC and electrospray ionization mass spectroscopy (ESI-MS), capable of processing the purification of two 96-well microtiter plates in parallel.
The system designed by Kassel et al. is comprised of two identical columns (analytical or preparative) running in parallel and is interfaced with two 96-well microtiter plates, each well containing a single synthetic product. Incorporation of a switching valve permits sequential loading of the samples onto the two columns: the autosampler draws the content of the first well of microtiter plate
1
and injects it onto the first column, then the autosampler picks up the content of the first well of microtiter plate
2
and loads it onto the second column. The same mobile phase is delivered to each column from a single HPLC pumping system, the flow from the pump splitting evenly between the columns (provided that the columns have comparable back pressures). Kassel et al. modified the IonSpray interface of the system to support flows from multiple columns and the eluents of the two columns were simultaneously introduced into the IonSpray source housing, and analyzed by mass spectrometry. This particular configuration allows the purification of chemical libraries based on mass spectrometry signal-detected fraction collection. Prior to performing the chromatographic separation, the mass and position of the expected products synthesized in the microtiter plate wells are specified. When a particular compound is detected by mass spectrometry in the course of the HPLC elution, the fraction collector connected to the column from which the compound is eluting is triggered, and the sample is collected in a specific tube determined by the position of the autosampler (for example, if the sample is drawn from well
1
of the autosampler/synthesis rack, the sample will be collected into tube
1
of the fraction collector rack). Thus, only compounds matching the molecular weight of the desired products are collected, and only one fraction is collected for each sample injected.
A major limitation of Kassel et al.'s parallel LC/MS technique is that the products to analyze must be of unique mass: false triggering of the fraction collectors is observed if two eluted compounds are of the same mass and similar ionization response. Thus, the synthesis of the combinatorial libraries must be carried out with the added restriction that no two expected products should yield the same molecular weight products. Further, for the flow to be equivalently transferred to the two columns requires that they have comparable back pressures because delivery of the solvent gradient is performed by a single pumping system. This generally requires that the columns be of the same size and be packed with the same chromatographic material. In addition, the design also dictates that both columns are eluted with identical mobile phase compositions. This limitation is usually of no consequence for the purification/purity assessment of combinatorial libraries, since the synthesized compounds are generally structurally related and exhibit similar chromatographic behaviors.
The Kassel et al. system is particularly well suited for one of the major challenges found in the pharmaceutical industry: high-throughput structure confirmation and purity evaluation of large numbers of compounds derived from combinatorial syntheses. However, it does not address the other essential aspect of the drug discovery process: the physicochemical characterization of large numbers of compounds derived from parallel synthesis for quantitative structure-activity relationships (QSAR) studies, and the implementation of massive screening techniques for the biological evaluation of compound libraries.
Micromass© (Manchester, UK) implemented a multiplexed electrospray interface that is capable of sampling four individual liquid streams in rapid succession. The system comprises a single pump delivering solvent to all four columns run in parallel. The system has been integrated with the Z-Spray ion source of the Micromass© LCT orthogonal acceleration time-of-flight mass spectrometer. The inner source housing contains an array of four pneumatically assisted electrospr
Giles Jeffrey
Lin Sonyuan
Pidgeon Charles
Rooke Nadege
Yin Jianming
Barnes & Thornburg
Sines Brian
Warden Jill
LandOfFree
Chromatographic systems with pre-detector eluent switching does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Chromatographic systems with pre-detector eluent switching, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chromatographic systems with pre-detector eluent switching will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3133553