Agilent Bravo Automated Liquid Handling Platform: 384-Channel 10 μL Tip Accuracy and Precision

Significance of the Topic

Automation of liquid handling at submicroliter volumes addresses the growing need for high-throughput, reproducible sample preparation in analytical chemistry and molecular biology. Precise dispensing reduces variability, minimizes human error, and supports applications such as genomic assays, compound screening, and cell-based experiments. The ability to reliably transfer volumes from 0.3 to 10 µL expands experimental flexibility and improves data quality across diverse laboratory workflows.

Objectives and Overview

This study evaluates the performance of the Agilent Bravo Automated Liquid Handling Platform equipped with a 384-channel ST disposable tip head and 10 µL tips at the lower end of its volume range (0.3, 0.5, and 2.0 µL). The goals are to quantify accuracy (closeness of dispensed to target volume) and precision (consistency of dispensed volumes) using a colorimetric assay. Outcomes inform suitability for low-volume applications and help guide protocol development.

Methodology

A tartrazine tracer assay was employed to determine dispense performance:

1. Prepare a 0.25% w/v tartrazine solution in DMSO and load 60 mL into a manual-fill reservoir on deck position 2.
2. Mount a 10 µL tip box on position 3 and a 384-well polystyrene plate on position 5.
3. Program VWorks software with liquid classes for 0.3–0.5 µL and 1–5 µL dispenses, setting aspirate and dispense heights, pre-aspirate and blow-out volumes.
4. Dispense target volumes (0.3, 0.5, 2.0 µL) into wells, perform a single-tip blow-out, then dilute each well to 50 µL with water using clean tips.
5. Centrifuge plates at 1800 rpm for 60 seconds, then measure absorbance at 405 nm to calculate dispensed volume via a tartrazine calibration curve.
6. Compute precision as coefficient of variation (CV=standard deviation/mean) and accuracy as percent deviation from target; report averages from three replicate plates.

Instrumentation

• Agilent Bravo Automated Liquid Handling Platform with nine configurable deck positions
• 384-channel ST disposable tip head
• 10 µL disposable tips (Agilent part 10734-202)
• 384-well flat-bottom polystyrene microplates (Greiner 781101)
• Agilent VWorks automation control software
• UV/Vis spectrophotometer with 405 nm filter

Main Results and Discussion

The Agilent Bravo with 384-channel ST head delivered consistent performance across the tested volume range:

• At 0.3 µL: precision 3.1% CV, accuracy within ±1.4%, with 42% of wells outside ±5% and 3% outside ±10%.
• At 0.5 µL: precision 2.0% CV, accuracy within ±1.5%, 10% of wells outside ±5%, none outside ±10%.
• At 2.0 µL: precision 1.3% CV, accuracy within ±1.6%, with no outliers beyond ±5%.
• Dispense times per 384-well plate: ~24 seconds at 0.3–0.5 µL; ~37 seconds at 2.0 µL.

Accuracy and precision improved with increasing volume, meeting or exceeding ±10% accuracy and ≤5% CV criteria across the range. Plate compatibility testing confirmed support for 96- and 384-well formats with 10 µL tips and for selected 1536-well plates using smaller volumes.

Benefits and Practical Applications

• Enables reliable micro-volume dispensing down to 0.3 µL, expanding low-volume assay capabilities.
• Reduces manual pipetting errors and variability in high-throughput workflows.
• Supports integration with thermal cycling, heating, cooling, and shaking modules for complex assay protocols.
• Compact design and laminar-flow compatibility facilitate cell culture and other contamination-sensitive operations.

Future Trends and Potential Applications

Automation platforms will continue to evolve toward even smaller volumes and higher channel counts. Integration with real-time analytics and feedback control may enable adaptive dispense correction. Expanded applications include single-cell analysis, next-generation sequencing library preparation, high-density plate screening, and closed-loop workcells combining sample prep with on-line detection. Enhanced tip technologies and software-driven liquid class optimization will further improve flexibility and throughput.

Conclusion

The Agilent Bravo with the 384-channel ST disposable tip head demonstrates high accuracy and precision for dispensing volumes from 0.3 to 10 µL, with CVs below 5% and accuracy within ±10%. Its configurability, speed, and plate compatibility make it a robust solution for diverse laboratory applications requiring reproducible micro-volume handling.

References

1. Holman JW, Mifflin TE, Felder RA, Demers LM. Evaluation of an automated preanalytical robotic workstation at two academic health centers. Clin Chem. 2002 Mar;48(3):540-8.