Parallel-column chromatography systems

The //PLC system described in this chapter is equipped with 24 parallel columns for liquid chromatography, each with its own sample introduction port and exit port for connection to detectors of choice (UV absorbance and/ or fluorescence). Flow from a binary solvent delivery system is divided evenly across 24 channels and results in 1/24 of the programmed pump flow rate through each column (i.e., total flow of 300 /zL/ min will produce a flow of 12.5 /zL/ min in each column). Samples are introduced to the columns by a multichannel autosampler configured to sample from either 96-or 384-well SBS standard plates. Figure 6.2 depicts a general view of the system. 

Another unique characteristic of this technology is the potential for online structure information collection. This HTP method utilizes a high-pressure chromatography system in a parallel processing mode, i.e., multiple simultaneous column runs coupled to a robot controlled liquid handling... 

Van Pelt, C.K. Corso, T.N. Schultz, G.A. Lowes, S. Henion, J. A Four-Column Parallel Chromatography System for Isocratic or Gradient LC/MS Analyses, Anal. Chem. 73, 582-588 (2001). 

Van Pelt, C.K. et al., A four-column parallel chromatography system for isocratic or gradient LC/MS analyses, Anal. Chem., 73(3), 582, 2001. 

Both liquid and gas chromatographic techniques have been developed to improve this analysis. Suatoni and co-workers (78,79) have performed most of the work by utilizing liquid chromatography. Soulages and Brieva (80) developed a gas chromatographic analysis that relies on selective adsorption of components. The sample is split onto three parallel columns. The saturates content is determined from one column that has a mercuric perchlorate-perchloric acid absorber for oleflns and aromatics. The second column is merely a delayer for a portion of the total sample. The third column has a mercuric sulfate-sulfuric acid absorber to retain the oleflns. Figure 13.25 is a typical chromatogram from this system. 

At the heart of the system is a cartridge that houses 24 liquid chromatography columns. This cartridge enables multiple samples to be analyzed in parallel. The 24 incorporated columns may be packed with... 

In 1995, when HPLC/MS/MS was becoming the premier tool for PK assays, chromatographic sample cycle times were typically 10 to 12 min. At 10 min per sample, 16 hr were required to process 96 samples. By 2000, scientists used shorter HPLC columns and per-sample cycle times decreased to 5 to 6 min. At 5 min per sample, it takes about 8 hr to assay one 96-well plate of samples. As a result, parallel HPLC became popular Korfmacher et al.154 described a two-column system and an MS vendor produced a triple quadrupole system designed to work with four HPLC columns.16155-158 Advances in fast chromatography continued and by 2005, sample cycle times of 1 to 2 min became common.21 87 159-161 At 2 min per sample, 3 hr are required to assay one 96-well plate of samples. 

Lindqvist, A., Hilke, S. and Skoglund, E. (2004) Generic three-column parallel LC-MS/MS system for high-throughput in vitro screens. Journal of Chromatography A, 1058 (1-2), 121-126. 

The experimental results are presented for the esterification of dodecanoic acid (C12H24O2) with 2-ethylhexanol (CsHisO) and methanol (CH4O), in presence of solid acid catalysts (SAC). Reactions were performed using a system of six parallel reactors (Omni-Reacto Station 6100). in a typical reaction 1 eq of dodecanoic acid and 1 eq of 2-ethylhexanol were reacted at 160 °C in the presence of 1 wt% SAC. Reaction progress was monitored by gas chromatography (GC). GC analysis was performed using an interScience GC-8000 with a DB-1 capillary column (30 m x 0.21 mm). GC conditions isotherm at 40 °C (2 min), ramp at 20 °C min" to 200 °C, isotherm at 200 °C (4 min). Injector and detector temperatures were set at 240 °C. Reaction profiles were measured for both non-catalysed and catalysed reactions. 

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