Spot-on UV/Vis accuracy with Lunatic & Stunner

Importance of the topic

Accurate and reliable UV/Vis measurements are fundamental for biologics workflows, where precise quantification of proteins and nucleic acids drives decision making in research, development, and quality control. Fast, low-volume verification of spectrometer performance minimizes downtime and ensures confidence in downstream analyses.

Objectives and study overview

This application note presents streamlined protocols for verifying the accuracy, precision, and linearity of Lunatic and Stunner microvolume UV/Vis spectrometers. Using certified reference materials and new software tools, the study covers performance evaluation across a broad absorbance and concentration range relevant to protein and nucleic acid analysis.

Methodology and instrumentation

Measurements were performed on Lunatic and Stunner instruments, both employing fixed-pathlength microcuvettes and microfluidic circuits with only 2 µL sample volume. Key reagents and reference materials included:

• NIST RM 8671 (NISTmAb) monoclonal IgG1K at 10 mg/mL
• NIST SRM 2082 pathlength absorbance standards (tryptophan and uracil)
• Unchained Labs Fundamentals kit with L-tryptophan at 1–8 mg/mL
• Gravimetrically diluted human serum albumin (HSA) and polyclonal IgG in various buffers

All samples were measured in octuplicate across five instruments. Data analysis used Lunatic & Stunner Client software v7.0 with automated reporting for accuracy, precision, linearity, and pathlength determination.

Main results and discussion

NISTmAb quantification on Lunatic showed bias under 1.25%, well within USP guidelines of 2% plus manufacturer uncertainty. Pathlengths derived from SRM 2082 absorbances fell within 2% of the nominal 10 mm. The Fundamentals kit yielded recoveries within 1% of target and RSDs below 1%, with a calibration slope of 0.9945 and R²=0.9999 for tryptophan. Gravimetric dilutions of HSA across seven levels produced inter-instrument CVs under 1.5%, while IgG dilution series from 0.1 to 200 mg/mL in PBS and acetate buffers exhibited linearity exceeding R²=0.9999. These results confirm excellent intra- and inter-instrument reproducibility and broad dynamic range.

Benefits and practical applications

• Rapid verification of UV/Vis accuracy and precision with only 2 µL sample
• Automated analysis and reporting streamline qualification and routine checks
• Applicable to protein therapeutics, nucleic acid assays, and QA/QC processes
• Reduced labor and materials by leveraging certified reference standards and software templates

Future trends and potential uses

Advances may include expanded certified reference libraries for other biomolecules, enhanced software workflows for higher throughput, integration with laboratory information management systems, and adoption in regulated environments for method validation and compliance. Ongoing improvements in microfluidics and optics will further extend concentration and viscosity ranges.

Conclusion

Lunatic and Stunner spectrometers offer spot-on UV/Vis performance across a wide concentration span, validated with NIST standards and a dedicated Fundamentals kit. Their high accuracy, precision, and linearity, combined with minimal sample volume and user-friendly software, make them ideal for fast, reliable quantification in modern biologics laboratories.

Reference

1. National Institute of Standards and Technology. RM 8671, NISTmAb Humanized IgG1K Monoclonal Antibody. Gaithersburg, MD, 2020.
2. National Institute of Standards and Technology. SRM 2082 Pathlength Absorbance Standards for Microliter Volume Spectrophotometers. Gaithersburg, MD, 2020.
3. United States Pharmacopeia 42 Chapter <857> Ultraviolent-Visible Spectroscopy.