Parallel HPLC

We developed a staggered parallel HPLC system with a CTC HTS PAL autosampler equipped with trio valves. The system consists of four (six if gradient is needed) independent HPLC pumps. Parallel analysis is achieved by an offset dual-stream system with a time delay that allows efficient staggering of MS acquisition times. 

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. 

For example, an 8-channel system with a modest separation time of 5 min can analyze 8 samples simultaneously, resulting in an average analysis time of 38 sec per sample. Another significant benefit of parallel HPLC is its application to procedures such as chiral column method development or... 

The percentage recoveries of M2D - C -> - 0 - (E 0 ) -CH3 over time in the presence of sand, soil and the clays kaolinite, halloysite and montmorillonite (0.1%, 10 mg g" -1) as determined by HPLC-APCI-MS methods are shown in Fig. 5.5.2 [10]. Validation of the data was obtained by parallel HPLC—LSD analysis (data not shown). 

A novel 24-channel HPLC by Nanostream called Veloce was introduced at PITTCON 04. The column cassette contains 24 parallel microbore columns. The eluted samples are detected by a 24-channel UV filter photometer. The advantage of such a system is that it allows one to work with multiple samples simultaneously. Other interesting systems for parallel HPLC were those introduced by Eksigent, based on microfluidic flow control, and Sepiatec GmbH, which allows the processing of 75 multiple-well plates. 

Multichannel HPLC—HPLC system designed to run parallel HPLC columns into a multi-flow cell UV or fluorescent detector. Designed for production laboratories to speed QA/QC monitoring (see Chapter 16). 

Zeng, L. Kassel, D. B. 1998. Developments of a fully automated parallel hplc/mass spectrometry system for the analytical characterization and... 

Interfacing the TEA to both a gas and a HPLC has been shown to be selective to nitro-based explosives (NG, PETN, EGDN, 2,4-DNT, TNT, RDX and HMX) determined in real world samples, such as pieces of explosives, post-blast debris, post-blast air samples, hand swabs and human blood, at picogram level sensitivity [14], The minimum detectable amount for most explosives reported was 4-5 pg injected into column. A pyrolyser temperature of 550°C for HPLC-TEA and 900°C for GC/TEA was selected. As the authors pointed out, GC uses differences in vapour pressure and solubility in the liquid phase of the column to separate compounds, whereas in HPLC polarity, physical size and shape characteristics determine the chromatographic selectivity. So, the authors reported that the use of parallel HPLC-TEA and GC-TEA techniques provides a novel self-confirmatory capability, and because of the selectivity of the technique, there was no need for sample clean-up before analysis. The detector proved to be linear over six orders of magnitude. In the determination of explosives dissolved in acetone and diluted in methanol to obtain a 10-ppm (weight/volume) solution, the authors reported that no extraneous peaks were observed even when the samples were not previously cleaned up. Neither were they observed in the analysis of post-blast debris. Controlled experiments with handswabs spiked with known amounts of explosives indicated a lower detection limit of about 10 pg injected into column. 

Performing parallel analysis of compound libraries offers many potential advantages over serial-based LC/MS analytical methods, the most obvious of which is dramatically increased compound analysis throughput. Using singlechannel HPLC-based purification systems, routine sample throughput of up to 192 reaction mixtures per 24-hour day was reported [64]. With parallel HPLC systems, it has been reported that the theoretical throughput increases to 384 samples per day for a two-channel system and to 768 samples per day for a four-channel system. 

R. God and H. Gumm, Parallel HPLC in high-throughput analysis and puriflca-tion, in B. Yan (ed.). Analysis and Purification Methods in Combinatorial Chemistry, John Wiley Sons, Hoboken, NJ, 2004, pp. 307-320. 

L Zeng, DB Kassel. Development of a fully automated parallel HPLC/MS system for the analytical characterization and preparation of combinatorial libraries. Anal Chem 70 4380-4388, 1998. 

At each interval, the relative standard deviation (RSD) of the NIR results at a wavelength specific to the active component Avas calculated. In addition, parallel HPLC analysis of the blend was performed. To show that the NIR method is comparable to results obtained by analysis by HPLC, the RSDs of the NIR results and the RSDs obtained from the HPLC assay results were plotted versus minutes mixed (Fig. 19). This experiment shows the feasibility of using NIR to determine the blend homogeneity of both API and excipients simultaneously in real time, thus ensuring optimal content uniformity during compression or capsule filling. 

Zeng, L. Kassel, D.B. Developments of a Fully Automated Parallel HPLC/Mass Spectrometry System for the Analytical Characterization and Preparative Purification of Combinatorial Libraries, Anal. Chem., 70(20), 4380 388 (1998). 

High-speed gradient parallel HPLC-MS/MS has been successfully used with fully automated sample preparation for bioanalysis. These techniques typically use a MUX interface and can provide analysis times as low as 30 s per sample. This technique suffers from instrument complexity that have dramatic consequences is system ruggedness [53],... 

The Chromatographic Analysis of Combinatorial Arrays Parallel HPLC and HPLC-MS... 

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