Automation of Sample Preparation and Introduction into NMR Tubes for Spectroscopy using VERSA™ Workstation

Abstract
Automation of sample preparation and introduction into nuclear magnetic resonance (NMR) spectroscopy tubes is required for high throughput NMR analysis, as high-throughput applications are hindered by manually loading and handling individual NMR tubes. However, automating NMR sample preparation is a challenging project as it may involve serial dilutions, mixing of different reagents and samples and liquid transfers. To solve these problems, Aurora developed a protocol enabling automation of all NMR-associated tasks, such as sample preparation and sample introduction, using Aurora’s 8-channel VERSA™ 1000 Workstation equipped with a plate shaker and ReagentDrop liquid handling module. In the validation protocol, bovine serum was added to serially diluted reagents in 96-well format, mixed with on-the-deck plate shaker, followed by addition of another reagent, mixed again, and followed by dispensing into the bottom of 5 mm NMR tubes arranged in 96-well format. Using this configuration, the VERSA™ 1000 can prepare 4 sets of 96 NMR tubes (396 NMR tubes) in one load, in one hour. 

Introduction
An NMR tube is a thin glass walled tube (1 – 5 mm diameter, with fill volume from 5 – 550 µL) used to contain samples in NMR spectroscopy (Figure 1). NMR spectroscopy is a versatile technique with applications including: qualitative and quantitative purity analysis for synthetic samples, quality control of compound libraries, screening small protein-binding molecules for pharmacological applications, analyzing metabolites in biological fluids like blood and serum, and searching for biomarkers or drug degradation products1. However, sample preparation provides a productivity bottleneck challenge for automation2. Dispensing highly volatile or viscous solutions into typical 5 mm ID NMR glass tube presents unique problems.

Automatic sample preparation systems for NMR spectrometers, which permit running multiple samples unattended, have been commercially available for some years3. In this era of information technology, NMR automation utilizing sample preparation systems has become a valued tool for both industry and academia. Depending on the laboratory's needs or goals, automation may involve high-throughput screening, overnight automation or multi-user open access, for example. Here we report preliminary studies into the feasibility of automating the preparation of such samples where prepared samples may be removed by temporarily interrupting the run.

Conclusion

• VERSA™ 1000 workstation can be used to prepare samples for NMR spectroscopy.
• VERSA™ 1000 Workstation is capable of automating processes involved with reagent additions and dilutions (pipette mixing or shaker mixing).