Unique Benefits of the Small Beam Geometry of the Agilent Cary 60 UV-Visible Spectrophotometer

Significance of the Topic

The precision and sensitivity of UV-Vis spectrophotometry are fundamentally driven by the efficiency of light delivery through the sample. The Agilent Cary 60’s unique small beam geometry concentrates all available light into a 1.5 mm × 1 mm focal spot, maximizing throughput, improving detection limits, and reducing noise. This design underpins advanced microvolume and remote measurement workflows, critical for high-throughput laboratories and challenging sample types.

Objectives and Study Overview

This technical note demonstrates how the Cary 60’s focused beam enables specialized accessories and novel applications. Key goals include showing performance with ultra-microvolume cuvettes, submicro cuvettes, fiber optic probes, and remote diffuse reflectance measurements of solids and liquids outside the sample compartment.

Methodology and Instrumentation

The Cary 60 employs a patented Xenon flash lamp coupled to an optical path that produces a highly focused beam at the sample position. This geometry ensures that every photon is directed through the sample, whether in standard or microvolume cells. Accessories include:

Used Instrumentation

• Agilent Cary 60 UV-Vis Spectrophotometer with small beam optical design
• Ultra-microvolume cuvette (2–10 µL capacity)
• Submicro cuvettes (10–135 µL) with apertures down to 2.0 × 2.0 mm
• Standard 3.5 mL quartz cuvettes
• Liquid and micro fiber optic probes
• Remote diffuse reflectance accessory (DRA) with integrated video camera

Main Results and Discussion

• Ultra-microvolume cuvettes delivered reliable photometric performance for sample volumes as low as 2 µL without special alignment or installation.
• The instrument sustained a linear absorbance range up to 2.3 Abs at 1 mm pathlength (equivalent to 23 Abs in 10 mm cells), eliminating routine dilutions.
• Submicro cuvettes with 2 × 2 mm apertures measured sample volumes between 40 and 135 µL with full signal throughput.
• Fiber optic liquid probes achieved high coupling efficiency and immunity to ambient light, enabling measurement in microcentrifuge tubes (down to 140 µL) and remote environments.
• The remote DRA accessory performed solid sample reflectance measurements up to 1.5 m away, capturing diffuse reflectance spectra of color standards with a 0/30° geometry.

Advantages and Practical Applications of the Method

• Minimal sample volume reduces reagent costs and conserves precious or hard-to-isolate analytes.
• High absorbance capacity removes the need for serial dilutions and simplifies workflows.
• Fiber optics and remote accessories eliminate cuvette handling and enable in situ measurements (e.g., fume hood, large solids).
• Non-destructive analysis preserves samples for downstream processes.
• Rapid switching between microvolume, standard cuvette, and remote modes enhances laboratory flexibility.

Future Trends and Potential Applications

Emerging opportunities include integration of the Cary 60 with automated microfluidic platforms and robotic sampling for fully unattended high-throughput screening. The small beam concept may be extended to hyperspectral imaging and process analytical technology (PAT) in manufacturing. Continued development of miniaturized accessories will broaden applications in life sciences, environmental monitoring, and advanced materials characterization.

Conclusion

The Agilent Cary 60’s small beam geometry delivers unmatched light throughput and coupling efficiency, enabling accurate measurements across a wide dynamic range of sample volumes and formats. Its versatility with microvolume cells, fiber optics, and remote accessories consolidates multiple analytical workflows onto a single instrument, driving productivity and lowering operational costs.

Reference

• Agilent Technologies. Unique Benefits of the Small Beam Geometry of the Agilent Cary 60 UV-Visible Spectrophotometer. Technical Note 5991-3852EN, August 15, 2014.