Analytical sample preparation

Analytical sample preparation may include extraction/purification, concentration/dilution, or modification, depending on the requirements of the analysis. Despite its importance, it comes with challenges such as maintaining repeatability, avoiding contamination, and managing labor-intensive workflows—especially when done manually. Automated systems can address these issues, providing greater accuracy, enhanced repeatability, time and labor savings, and reduced contamination risks.

Manual standardization, standardization using a liquid handling system, and standardization using a microplate reader are some of the ways to perform this process. However, automated systems are increasingly favored due to their greater accuracy, repeatability, and efficiency, as well as reduced contamination risk.

Analytical sample preparation workflow

Analytical sample preparation is fundamental to many workflows in molecular biology and proteomics:

1. PCR and qPCR: In these procedures, sample preparation includes extraction and purification of DNA or RNA.
2. Next-generation sequencing (NGS): In the NGS workflow, sample preparation involves steps such as DNA fragmentation, adapter ligation, and amplification.
3. Protein analysis: For protein analysis like ELISA or Western blot, sample preparation may include protein extraction, quantification, and possible denaturation.
4. Cell experiments: In these experiments, sample preparation may include culturing the cells, treating the cells with specific compounds, and then possibly lysing the cells to release their contents.

Best Methods for Analytical Sample Preparation

1. Extraction/Purification: This may involve DNA or RNA extraction processes like phenol-chloroform extraction, or various chromatographic techniques for protein purification.
2. Concentration/dilution: Samples may need to be concentrated using methods such as centrifugal filters, or diluted to a concentration suitable for analysis.
3. Modifications: Some assays require chemical or enzymatic modification of the sample prior to analysis. For example, proteins may need to be denatured and reduced before running SDS-PAGE.

Why is analytical sample preparation so difficult?

Analytical sample preparation is often considered the most challenging part of the experimental process. It requires a high degree of precision and accuracy to ensure reproducible results. At this stage, the sample is most susceptible to contamination or degradation, which can lead to inaccurate results. Furthermore, optimal sample preparation protocols may vary significantly depending on the sample type and specific analysis.

Key challenges in analytical sample preparation using manual pipetting

1. Reproducibility: Even small changes in pipetting technique can lead to significant differences in results.
2. Contamination: Samples are susceptible to contamination during preparation, especially when pipetting manually.
3. Time and Labor Intensive: Manually preparing samples for analysis can be time-consuming and labor-intensive, especially when processing large numbers of samples.

Automated preparation of analytical samples

Automation of analytical sample preparation can be achieved with robotic liquid handling systems. These systems can accurately dispense precise volumes, mix reagents, and even perform operations such as heating or cooling. Using these systems reduces human error, increases reproducibility, and significantly speeds up the sample preparation process.

Advantages of automated sample preparation for analysis compared to manual preparation

1. Improved reproducibility: Automated systems ensure consistency in sample processing conditions, thereby improving reproducibility between experiments.
2. Save time and labor: Automated systems are able to process multiple samples simultaneously, significantly reducing the time and labor required.
3. Reduced risk of contamination: Automated systems reduce the amount of manual handling, thereby reducing the risk of contamination.