Micro Volume Photometric Measurement of Nucleic Acid using TrayCell with UV-1280

Importance of the Topic

Accurate quantification of nucleic acids is fundamental in molecular biology, clinical diagnostics, and quality control. Microvolume UV-Vis spectrophotometry minimizes sample consumption, reduces preparation time, and lowers the risk of contamination, making it a preferred approach for DNA and protein analysis in modern laboratories.

Objectives and Study Overview

This study demonstrates the performance of the Hellma TrayCell ultra-micro cell combined with the Shimadzu UV-1280 spectrophotometer in bio method mode for reliable microvolume photometric measurement of nucleic acids. Key aims include assessing reproducibility, evaluating practical workflow benefits, and verifying purity metrics based on absorbance ratios.

Methodology and Instrumentation

Sample: 100 bp DNA ladder (Promega), measured at 260 nm with 3 µl volume.
Process:

• Blank and sample dispensing onto the TrayCell window.
• Cap insertion to establish defined optical path (1 mm or 0.2 mm).
• Baseline correction and measurement initiation via UV-1280 interface.

Used Instrumentation:

• Shimadzu UV-1280 UV-Vis spectrophotometer with built-in bio method mode.
• Hellma TrayCell ultra-micro cell (fiber-optic design) with interchangeable 1 mm and 0.2 mm caps.

Main Results and Discussion

Ten replicate measurements of the DNA ladder at 260 nm yielded an average absorbance of 0.275, standard deviation of 0.004, and relative standard deviation of 1.32 %, demonstrating high repeatability. Purity assessment through A260/A280 (optimal ~1.8–1.9 for DNA) and A260/A230 (>2.0) ratios ensures sample integrity and identifies potential protein or phenol contaminants.

Benefits and Practical Applications

• Minimal sample volume requirement (0.7–10 µl) reduces reagent costs and sample waste.
• Virtual dilution via shorter path lengths avoids manual dilution steps and associated errors.
• Fiber-optic design simplifies cleaning and lowers carryover risk.
• Applicable to DNA and protein quantification workflows in research, QA/QC, and clinical settings.

Future Trends and Potential Applications

Advancements may include integration of microvolume cells into automated, high-throughput platforms and combination with fluorescence detection for enhanced sensitivity. Portable, field-deployable microvolume spectrophotometers are expected to expand on-site testing capabilities in environmental and clinical domains.

Conclusion

The Hellma TrayCell paired with the Shimadzu UV-1280 spectrophotometer offers a robust, reproducible method for microvolume nucleic acid analysis. Its ease of use, minimal sample requirements, and reliable purity assessment make it a valuable tool in modern analytical laboratories.

Reference

1. SHIMADZU (Asia Pacific) Pte. Ltd. Application Note AD-0088: Micro Volume Photometric Measurement of Nucleic Acid using TrayCell with UV-1280 (2015).