Liquid handlers

The immobilized carbamates (40 pmol) were transferred to a sealable 96-well Weflon plate, and admixed with 10 pmol each of various primary or secondary amines dissolved in 400 iL of anhydrous toluene. After sealing, the plate was irradiated in a multimode microwave instrument, first generating a ramp to reach 130 °C within 45 min and then holding this temperature for an additional 15 min. After cooling, the resins were filtered with the aid of a liquid handler and the filtrates were concentrated to obtain the desired substituted ureas in good purity and reasonable yields. Anilines reacted rather sluggishly and 2-substituted benzyl carbamates afforded somewhat inferior results. 

Syringe-barrel cartridges, disk-holders, plastic pipette-tips, well plates vacuum manifolds for semiautomatic batch processing fully automated autosamplers, xyz liquid handlers and robot-controlled work stations. 

The two major approaches for HPLC purification are fast gradient separation and parallel purification. Yan et al.178 utilized the former (Figure 1.51). The purification lab received a 96-well plate containing synthesized products at 0.1 to 0.2 mmol/well. A Hydra 96-probe liquid handler prepared QC plates for all samples that were analyzed with a MUX-LCT eight-channel parallel LCMS instrument at a throughput of 2000 samples/day. Only samples with purities above 10% were purified on a... 

Preparative reversed-phase HPLC purification was carried out using Gilson liquid handlers and HPLC equipment controlled by Unipoint Version 3.2 software. Initial and final HPLC gradient... 

Automation using a robotic liquid handling system eliminated most of the tedious steps encountered with traditional manual extraction procedures. Automated 96-well SPE and LLE techniques using robotic liquid handlers have been successfully implemented to support high-throughput bioanalysis.5... 

A second strategy relies on parallel experimentation. In this case, the same experimental step is performed over n samples in n separated vessels at the same time. Robotic equipment such as automated liquid-handlers, multi-well reactors and auto-samplers for the analysis are used to perform the repetitive tasks in parallel. This automated equipment often works in a serial fashion as, for example, a liquid handler with a single dispensing syringe filling the wells of a microtiter plate, one after another. However, the chemical formation of the catalyst or the catalytic reaction are run at the same time, assuming that their rate is slow compared to the time needed to add all the components. The whole process appears parallel for the human user whose intervention is reduced. 

If SPA has shortcomings, and every assay technology does, they include its requirement for pipetting beads, which can be challenging for liquid handlers, and its use of radioisotopes. 

Automation in derivatization has led to the development of pre-colnmn and post-column HPLC techniqnes. In post-column derivatization, the separated components elnting from the colnmn are derivatized on-line in a heated mixing coil prior to entering the detector. Pre-column derivatization can be performed in many autosamplers or automated liquid handlers. 

Gilson 215/889 8-Probe Multi-Injector Liquid Handler... 

Gilson. The Gilson 215 Liquid Handler is a versatile, large-capacity, septum-piercing liquid handler for safe and efficient transfer. It helps transferring samples to other analytieal systems or inject samples directly to an on-line HPLC system. 

Fig. 12.2 Diagram of a fully automated system for acquiring H/D exchange MS data starting with a stock solution of the nondeuterated protein. In this system [8], the liquid handler mixes a small amount of concentrated protein solution with a selected deuterated buffer and the mixture is incubated for a programmed period of time. The exchange reaction is conducted in a temperature-controlled chamber held at 25 °C. The mixture is then transferred to an acidic quench solution held at 1 °C. After quenching the exchange reaction, the entire sample is injected onto an LC-MS system...

Enrichment of high affinity candidates is usually achieved in 8 to 15 rounds of SELEX. Each rotmd takes approximately 2 days to perform. The process has been automated using robotic liquid handlers both for DNA (SomaLogic) and RNA aptamers (Cox, 2002). Next, the sequenced aptamer is prepared in bulk by conventional DNA synthesis chemistry and purified, then the aptamer arrayed onto a solid support. Thus, an aptamer is ready for application within 2 to 3 mo. Because the sequence is known, preparation of additional aptamer is easily accomplished using conventional oligonucleotide chemical synthesis. 

Using a liquid handler, transfer the contents of each test tube to its corresponding well in a 2-mL 96-well polypropylene deep-well plate for purification by HPLC. 

Using a liquid handler, remove 5 iL of the solution from each well, dilute the aliquot to 1.0 mL with MeOH/water 95 5 in a new deep-well plate for LC/MS analysis. 

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