GC/MS system from Agilent Technologies Inc. equipped with a GERSTEL MPS roboticpro for automated sample preparation. The MPS is configured with Dynamic Headspace (DHS) option. The standard DHS system uses 20 mL vials – a version that uses 1 Liter sample containers (DHS Large) is also available.

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What should you look for when buying a new autosampler for GC/MS and LC/MS

Laboratories carefully analyze their current requirements for productivity and efficiency before investing in autosamplers for GC/MS and LC/MS. It also makes sense to look at automation potential, specifically automated sample preparation.

By Ralf Bremer

Every GC/MS and LC/MS laboratory today faces ever-increasing productivity and efficiency demands. Typically the number of samples keeps increasing, but staff is not added or is even reduced. To make matters even more challenging, there is constant pressure to reduce cost, save energy and to eliminate or reduce the amount of potentially toxic solvents used. Also, it is necessary to have maximum flexibility as new sample types require new methods for sample preparation and analysis, but with the same turnaround as standard analyses. To meet all demands and keep the customer satisfied, a good start is to automate manually performed routine sample preparation tasks. Typical examples are generating standards or dilution series - or adding an internal standard or derivatization reagent. But the possibilities are, if not endless, more extensive than most people would think, provided you have the right automation platform. So when you are trying to decide which autosampler is best for your needs, it is a good idea to carefully determine which manual steps in your workflow can be automated and make sure you find an autosampler that fits these needs. There are significant differences between automation platforms – especially in the sophistication of the software used to automate more advanced sample preparation steps, so it is critical that these features are thoroughly evaluated.

Basic autosampler functionality is a good indicator of success

A modern autosampler based on an X-Y-Z robot, such as the GERSTEL MultiPurpose Sampler (MPS), can perform almost unlimited tasks since it moves unrestricted in three dimensions and can access a large number of sample positions. Standard tasks include sample introduction to GC/MS or LC/MS or simple sample preparation steps like adding an internal standard. This is a good starting point, but one needs to look deeper. Maybe you need a sampler to perform dilution series or generate a series of calibration standards. All this must be accompanied by enough syringe- or valve rinsing possibilities to eliminate sample-to-sample carryover and cross contamination.

Advanced functionality on demand

If more advanced sample preparation tasks need to be performed at a later time, can these be added to the system in a modular fashion? Which options and accessories are typically added? Examples include filtration or solid phase extraction (SPE), liquid-liquid extraction (LLE), centrifugation, solvent evaporation, solid phase micro-extraction (SPME), stir bar sorptive extraction (SBSE) as well as static and dynamic headspace (HS/DHS). A fully loaded autosampler is rarely needed, but it is very useful to be able to add these capabilities on demand with little effort or additional expense.

On the sample storage side, a wide range of sample vessels should be accommodated. These should include deep well plates, and standard vials and even customized trays for any container you might need in your method. The possibility of storing samples cold in order to eliminate analyte degradation and preserve sample or reagent integrity - or of heating and agitating after a reagent has been added - should be available as options.

The Dual Head version of the MPS can perform different tasks simultaneously for improved productivity and flexibility; this includes handling vastly different liquid volumes using two different syringe sizes. Having both of these mounted in the Dual Head MPS offers a higher degree of flexibility and productivity since you do not have to manually change the syringe or wait for the syringe to be changed (available with the MPS robotic pro) during the sample preparation method.

The little differences that mean a lot

Can the autosampler be fitted with a separation technique such as a centrifuge? Can it do vortexing and solvent evaporation? Can liquids be added under highly controlled conditions and the amount determined using a balance? The availability of any of these capabilities can be the deciding factor in finding the right solution for your needs when automating manual sample preparation processes and making them fully traceable on a 24/7 basis.

Application and integration requirements

Is the autosampler needed for sample introduction directly into the GC/MS or LC/MS system? If so, wouldn’t it be helpful to perform sample preparation and analysis in parallel? This would ensure that samples are always prepared immediately before being analyzed and could maximize system utilization. Or will the system mainly be used as a separate workstation to generate standards and dilution series for the analysis instrument(s)? The clearer the definition, the easier it is to select the right autosampler, both for current and for future requirements. The main sources for information and comparisons are Laboratory Magazines and their websites. Laboratory Instrumentation Exhibitions such as PittCon, ASMS and Analytica in Europe can also serve to enable comparisons in a short time span. Obviously vendor websites offer detailed information, typically with a lot of application examples. GERSTEL is among the leading providers of intelligently automated solutions for GC/MS and LC/MS. If you are considering automating your sample preparation and -introduction, please contact your local GERSTEL representative. We have many years of experience applying our automation solutions to real world samples and applications. If you let us know what you want to achieve, we will listen carefully before proposing a solution that truly fits your needs.

A modern GC/MS Laboratory. The analysis systems are equipped with high performance autosamplers that can automate all steps in sample preparation and introduction. The high degree of automation helps ensure productivity and throughput while offering enough flexibility to easily adapt to new sample types, analysis methods and performance requirements.

What you should consider when you choose your next autosampler

1. Keep it simple. It may sound nice to have an autosampler that can do everything, but it can add unnecessary cost and operational complexity.

2. The software package is your everyday interaction with the instrument. Make sure it is as easy as possible to operate and that it adapts directly to the instrument configuration to eliminate unnecessary complexity, it should be “plug and play”. Also, you should be able to change and adapt methods and sample preparation processes without the need for programming steps and external support.

3. Plan your purchase and your laboratory automation with your mid-to-long term strategies and goals in mind. Limit your investment to fit your current needs, but make sure that technologies can be added at a later time as your needs change without having to purchase completely new systems and rendering the initial investment obsolete. Even if the plan is to automate liquid-liquid extractions, it can be beneficial to be able to update the system to perform evaporation, filtration, SPE or even headspace.

4. Make sure you get good support. Laboratory autosamplers are high-tech products and they often need individual implementation depending on the sample types and performance requirements. Make sure the supplier has the experience and resources to provide efficient technical and application support without delay.

5. Consider existing systems in the laboratory. New autosamplers can upgrade existing GC/MS or LC/MS systems to a higher performance level by removing interfering matrix compounds or concentrating analytes. Relying on existing systems in the laboratory could provide significant savings.

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