Improving Quality Control for Nucleic Acid Analysis

Every molecular biology application has defined standards for nucleic acid concentration, purity, and fragmentation. More sensitive applications may require rigorous quality control (QC), whereas some other methods might tolerate certain impurities or fragmentation. Regardless of the application, pure, intact, and highly concentrated nucleic acids often improve the results of downstream processes. For these reasons, researchers should prioritize QC strategies that enhance reliability and accuracy while minimizing time wasted on failed samples and troubleshooting.

Common challenges

Despite best efforts, researchers face many challenges that can compromise the accuracy of nucleic acid analysis. Angelica Olcott, Market Development Manager at Bio-Rad Laboratories, explained that some of these key issues include problems with sample quality and integrity from degraded nucleic acids or contamination with proteins, salts, or inhibitors. For instance, inhibitors like heme, urea, and ethanol can disrupt the amplification of target nucleic acids and interfere with their quantification in various PCR techniques. Additionally, Olcott noted that complex data analysis and issues with calibration and maintenance on various lab instruments can contribute to inconsistent results, false positives, or misinterpretation.

“Another significant challenge is ensuring consistent yields, especially when working with difficult sample types or variable extraction methods,” stated Samantha Lewis, Product Manager at Promega. Differences in operator technique, consumables, and starting materials can further exacerbate this problem. This type of variability can lead to inaccuracies during quantification steps and suboptimal inputs for downstream assays.

Key QC strategies

Fortunately, researchers can take routine steps to improve their QC processes and downstream applications. The most common QC approaches typically assess and optimize the size, purity, and concentration of target nucleic acids.

Spectrophotometry and fluorometry are the primary methods for evaluating concentration. Spectrophotometers offer a quick way to measure nucleic acid purity using absorbance ratios, but they can be affected by contaminants like proteins or residual solvents. In contrast, fluorometric quantification tools provide greater accuracy and are less prone to overestimation errors. However, they typically can’t detect contaminants and may be most effective when used with complementary methods.

To assess nucleic acid size and fragment distribution, researchers often use gel electrophoresis or, more commonly, microfluidic capillary electrophoresis for faster and more precise analysis. These methods confirm sample integrity and provide an estimate of nucleic acid concentrations. Meanwhile, electrophoresis and spectrophotometry can also provide insight into sample purity by detecting impurities that might interfere with downstream applications.

Alongside these QC measures, Olcott stressed the importance of choosing high-quality reagents and selecting the right technology for each application. She highlighted droplet digital PCR (ddPCR) as particularly beneficial for challenging environmental samples and low-copy target detection. “ddPCR is far less affected by PCR inhibitors than qPCR, and it enhances data integrity by providing precise, sensitive, and reliable quantification of nucleic acids without the need for calibration curves,” Olcott explained. Furthermore, she recommended using specialized software to simplify plate setup, data collection, analysis, and visualization for real-time PCR workflows.

Integrating automation into laboratory workflows, especially for nucleic acid extractions, is an effective tool to reduce variability. Lewis emphasized that automation reduces manual steps that could lead to failures while also maintaining consistent quality. “Standardizing protocols can ensure your QC metrics are hit more consistently. Also, implementing checkpoints, such as measuring concentration and integrity using a dye-based or qPCR method, at critical stages can also help catch compromised samples early, thus saving resources spent running them all the way through the workflow,” Lewis added.

Beyond process automation, Lewis noted that using protective additives and correct sample storage can further preserve nucleic acid integrity for downstream applications. These additives can effectively block a wide range of RNases and protect against contamination, particularly for sensitive RNA samples used in RT-qPCR and other RNA applications.

Recent innovations

Recent technological developments have introduced new tools that improve nucleic acid analysis while reducing the burden of rigorous QC measures. Lewis explained that her team at Promega is developing formulations capable of tolerating a wider range of sample types and potential contaminants, reducing the need for extra cleanup steps. For example, their GoTaq^® Endure, an inhibitor-tolerant master mix, ensures reliable PCR amplification by resisting inhibitors from blood, plant, and soil extracts. “This not only saves valuable time and resources but also bolsters confidence in every PCR run, even with the most challenging sample types,” stated Lewis.

Similarly, Olcott highlighted key advancements at Bio-Rad, including enhanced automation for PCR and qPCR systems to improve throughput and minimize errors, as well as customizable packaging and labeling solutions for PCR plastics and reagents. She also noted the expansion of PrimePCR assays into new applications, providing pre-validated options for specialized research. These innovations, Olcott explained, streamline laboratory workflows and give scientists the tools to achieve more efficient, reliable, and reproducible PCR results.

Final advice

Researchers can also strengthen their QC processes and optimize downstream applications without straining their budgets by implementing practical, cost-efficient strategies. This starts with a proper experimental setup. “Use positive and negative controls and replicates to monitor performance and contamination and ensure reproducibility,” encouraged Olcott. She also advised researchers to regularly calibrate instruments with manufacturer support to prevent costly downtime and ensure that lab personnel are well-trained on the equipment and its applications. Moreover, maintaining aseptic technique and using high-quality consumables further preserve sample integrity and minimize contamination risks.

In addition to proper technique and controls, Lewis emphasized that small, targeted changes can greatly improve overall data quality. These changes include standardizing nucleic acid extraction and quantification methods, such as using fluorescent dyes instead of absorbance, which can reduce variability and improve reproducibility, especially at low concentrations. Incorporating inhibitor-tolerant reagents also helps minimize the need for repeat experiments to further conserve resources. “Another cost-effective tip is to automate where possible,” noted Lewis. Small-scale automation tools can minimize hands-on time, reduce errors, and keep costs in check. Finally, Lewis recommended clear training and SOPs to ensure consistency and prevent QC issues before they escalate.