High-throughput evaporation

Products /technologies Atlas high-throughput evaporators are designed to meet the demands of combinatorial chemistry, parallel synthesis, natural products research, and HPLC prep. The new technology and large sample capacity allows rapid evaporation of up to 1 liter or more of even the most difficult solvents in a few hours at low or moderate sample temperatures suitable for use with most sample formats, including microtiter plates, test tubes, and vials. 

For high-throughput evaporation, vacuum centrifuges are currently the devices that are in most tvidespread use. Equipment using orbital shaking as an alternative has also become available from several vendors. 

Hilfiker et al. at Solvias used carbamazepine (CBZ) as a model compound to describe the use of Raman microscopy to characterize crystal forms, including during solvent evaporation experiments [228], The spectra were processed into clusters by spectral similarity. The authors note that all published and several new crystal forms were identified during the study. Solvias HTS uses a specific set of crystallization protocols that have tended to produce new polymorphs. Hilfiker notes that Raman microspectroscopy is an ideal analytical tool for high-throughput discrimination between crystal structures. [229], The ability to collect spectra directly and automatically in a microtiter plate with or without solvent and during evaporation is a major advantage over many other techniques. 

The first semi-high-throughput automated system to dispense crystallization trials of less than 1 jl1 was designed in 1990 to deliver batch trials imder oil (Chayen et ah, 1990). The method was named microbatch to define a microscale batch experiment. It was designed to obtain maximum information on the molecule to be crystallized while using minimal amounts of sample. In order to prevent the evaporation of such small volumes, the trials are dispensed and incubated under low density (0.87 g/cm ) paraffin oil (Fig. 3.2). The crystallization drops remain under the oil since the aqueous drops are denser than the paraffin oil. 

A recently reported alternative to spin or spray coating is screen printing of polyimide solutions (82, 85, 90). Screen printing is a low-cost, high-throughput process capable of directly patterning the polyimide films as they are deposited. Another alternative is the vapor deposition of polyimides, which was reported by researchers who co-evaporated the diamine and dianhydride monomers at stoichiometric rates (140). The evaporated films had better adhesion, a lower dielectric constant, and a lower dissipation factor compared with spin-coated polyimides. With this process, uniform, defect-free, conformal films can be cured in situ during deposition. 

Although the direct oxidation of ethane to acetic acid is of increasing interest as an alternative route to acetic acid synthesis because of low-cost feedstock, this process has not been commercialized because state-of-the-art catalyst systems do not have sufficient activity and/or selectivity to acetic acid. A two-week high-throughput scoping effort (primary screening only) was run on this chemistry. The workflow for this effort consisted of a wafer-based automated evaporative synthesis station and parallel microfluidic reactor primary screen. If this were to be continued further, secondary scale hardware, an evaporative synthesis workflow as described above and a 48-channel fixed-bed reactor for screening, would be used. 

Tan A, Hussain S, Vallee F (2009) Evaporation-free extraction and application in high-throughput bioanalysis by LC-MS/MS. LCGC North America 27 414 127... 

After the fractions have been collected, the solvent needs to be removed by using a freeze-dryer, rotary evaporator, or high-throughput parallel evaporator. Nonvolatile components can be removed with reversed-phase SPE procedures prior to solvent removal if the aqueous portion of the buffer is sufficiently large. 

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