Extraction is a commonly used process for sample preparation. Extractions can be performed as liquid-liquid or liquid-solid phases. The use of solid phase extraction, also known as SPE, is common in many laboratories and is a common sample preparation step for GCMS, LCMS, and many other analytical methods. For SPE, Zinsser offers the Speedy, a robotic platform that is optimized for automated solid phase extraction.
The Zinsser Analytic Speedy is an automated Solid Phase Extraction system that can operate with 96-well format filter plates or with 1-5 ml cartridges. The SPEEDY can operate with either a vacuum-based SPE system or a positive pressure system that addresses the inherent drawbacks of the 96-well format that is traditionally run with vacuum.
The Speedy platform is configured with four variable-spacing probes and a robotic gripper. The gripper is shown here holding a vacuum manifold with a filter plate in preparation for placement on the vacuum box. The gripper can remove the manifold, store it temporarily, place the collection plate on the vacuum box, then return the manifold for the final extraction step. Pulsed vacuum is then applied via the WinLissy software.
Performing vacuum-driven SPE with 96-well format filter plates is a suitable method if all samples are of uniform consistency, however this method can present some inherent problems that can be difficult to overcome with tough samples such as plasma or other biofluids. These problems are mainly due to the mechanism of attempting to pull a uniform vacuum through all 96 positions.
These problems can lead to low recoveries and variable results when using vacuum-based SPE filtration methods.
Speedy can overcome these problems by using positive pressure applied from the top instead of vacuum. The system is configured with 2-channel probes that can be used to deliver either liquid or gas (usually nitrogen). The probes pick up special cartridge adaptors or pressure spots that are then placed directly on top of the SPE cartridge. The system can work with 1, 3, or 5 ml SPE cartridges in this manner. The cartridge adaptor forms a seal within the SPE cartridge allowing the probe to pressurize the internal environment. The positive pressure technique provides the additional benefit of keeping the sample in an inert environment, which is particularly useful for samples that are sensitive to oxidation.
Speedy enhances the positive pressure technique by using digital pressure control and independent active monitoring of the pressure within each cartridge. The initial applied pressure is kept lower so that splashing does not occur within the cartridge. The pressure is then increased to a steady level for the extraction phase. The software will recognize the pressure drop that occurs when the cartridge is cleared of liquid and can shut down pressure independently for each cartridge, preventing unnecessary compression of the filter be and drying-out of samples.
With the positive pressure system optimal and reproducible extraction conditions for each sample are assured, regardless of the sample viscosity, filter variations, or other variable conditions. The result is finally an automated SPE system that can produce large numbers of SPE extractions without operator intervention, removing the tedium of manual SPE lab work.
|Typical vacuum SPE: Recommended collection height places cartridge tips above the wells of the receiving plate.||Typical vacuum SPE: Cross-contamination can occur during vacuum application due to localized splashing near top of receiver plate wells.||Speedy: Tight seal of cartridge adaptor to the SPE cartridge allows positive pressurization via the probe and eliminates cross-contamination between samples.|
It is also possible to automate liquid-liquid extraction (LLE). LLE with various solvents is also available on SPEEDY using either a single tube vortexer for large volume extractions, or a multiposition vortexer for smaller volumes, both of which can vortex up to 1800rpm. Solvents are dispensed rapidly via a 6 way-valve. SPEEDY detects the different heights of the organic / aqueous phases and aspirates the phase of interest accordingly. SPEEDY can also prepare the chromatography vials required for the analysis of extracted analytes; preparing any dilutions required, sealing the vials, and finally the option to load samples directly from the workbench through an injection port.
Another common sample preparation method is a single-step filtration of the sample, typically accomplished by pushing the sample liquid through a membrane of cartridge disk. We can adapt any type of filtration media of your choice using custom racks to automate the filtration process.
Zinsser automated liquid handling platforms are unique on the market because of the selection of high-performance tools that can be installed on the deck. The ability to select from this list of tools allows the user to configure a system that will fully automate the required application, whether it requires liquid handling, powder handling, weighing, heating, cooling, vortexing, pressurization, vacuum, or almost anything that can be imagined.