Determine Protein Concentration Using Microvolumes with the Agilent Cary 60 UV-Vis Spectrophotometer

Significance of the Topic

Protein concentration measurement at microvolumes is essential for biochemical, clinical and industrial laboratories. Conventional methods often require large sample volumes and serial dilutions, leading to increased time, cost and potential errors. Microvolume UV-Vis analysis preserves precious samples and accelerates workflows.

Study Objectives and Overview

This article illustrates how the Agilent Cary 60 UV-Vis spectrophotometer combined with an ultra-microvolume cuvette enables direct protein quantification without dilution. The focus is on assessing photometric linearity, detection limits and operational efficiency.

Methodology

Bovine serum albumin (BSA) samples covering concentrations from 0.001 mg/mL to 190 mg/mL were analyzed in as little as 3 µL volumes. Different cap path lengths adjust measurement range, while nondestructive sampling and simple cleaning streamline the process.

Used Instrumentation

• Agilent Cary 60 UV-Vis Spectrophotometer
• Ultra-microvolume cuvette with mirrored caps (1.0 mm and 0.2 mm path lengths)
• Optional standard 10 mm cuvette for extended low-concentration detection

Key Findings and Discussion

The system delivers superb photometric linearity up to equivalent absorbances of 23 Abs with the 1.0 mm cap and 115 Abs with the 0.2 mm cap, enabling direct measurement of BSA from 0 to 190 mg/mL. Switching to a 10 mm path length extends the detection limit down to 0.001 mg/mL. Compared to traditional cuvettes, the approach offers faster turnarounds and enhanced reproducibility.

Benefits and Practical Applications

• High accuracy and repeatability across a wide concentration span
• Minimal sample volume requirement and nondestructive analysis
• Quick cleaning with no carryover
• Flexible detection tuning via interchangeable caps and cuvettes

This method is ideal for routine protein assays, enzyme kinetics studies, dilute sample measurements and quality control in research, clinical and industrial laboratories.

Future Trends and Potential Applications

Emerging developments may include automated multicell changers, temperature-controlled cuvette holders, advanced kinetic analysis software and integration into microfluidic systems for high-throughput screening and point-of-care diagnostics.

Conclusion

The Agilent Cary 60 UV-Vis spectrophotometer with ultra-microvolume cuvettes offers a robust, time-efficient and versatile solution for accurate protein quantification in microvolumes, meeting the evolving needs of modern analytical laboratories.