The Advantages of Automated Sample Preparation

Importance of the Topic

Automated sample preparation has become a critical advancement in analytical chemistry, particularly for laboratories conducting quantitative analyses. By standardizing dilution and calibration routines, automation minimizes human-induced variability, accelerates workflow, and conserves valuable resources. Such reliability is vital when generating accurate calibration curves and meeting regulatory requirements for trace-level compound quantification.

Objectives and Study Overview

This application note focuses on the automated preparation of a seven-point calibration curve for polycyclic aromatic hydrocarbons (PAHs). The study aims to demonstrate the reproducibility and accuracy of an automated dilution routine executed on a FLEX Series autosampler and to validate the resulting calibration curves using gas chromatography–mass spectrometry (GC-MS). Four replicate curves were prepared and analyzed to assess precision, linearity, and recovery performance.

Methodology and Instrumentation

The automated workflow employed a FLEX Series autosampler programmed to dilute two primary PAH standards (20 µg/mL and 500 µg/mL) into seven calibration levels across a 1 mL final volume. Dilutions were performed in a 2 mL tray using a 500 µL syringe, following predefined solvent and sample handling parameters. The diluted standards were then injected via a 10 µL syringe into an Agilent 7890 GC coupled to a 5975C mass selective detector. A Restek Rxi-5ms column (30 m × 0.25 mm × 0.25 μm) was used for chromatographic separation under a multi-stage temperature program.

Used Instrumentation

• FLEX Series liquid autosampler with 500 µL and 10 µL syringes
• Agilent 7890 gas chromatograph
• Agilent 5975C mass spectrometer
• Restek Rxi-5ms capillary column (30 m × 0.25 mm × 0.25 μm)

Main Results and Discussion

Linearity across the four replicate calibration curves exhibited average relative standard deviations (%RSD) below 3% for all 16 PAH analytes, meeting USEPA Method 8270D criteria. Recovery of a 50 ng mid-range standard yielded an average value of 91.7% with an average precision of 2.6% RSD. These results demonstrate the automation routine’s high repeatability, accuracy, and compliance with regulatory standards.

Benefits and Practical Applications

• Consistent preparation reduces analyst variability and error
• Efficient use of time and consumables enhances laboratory throughput
• Meets stringent quality requirements for environmental and industrial testing
• Streamlines production of calibration standards and QC samples

Future Trends and Potential Applications

Advances in laboratory automation are extending to multiplexed sample preparation, integration with laboratory information management systems (LIMS), and AI-driven protocol optimization. Future developments may enable fully unattended workflows for complex matrices, on-line sample cleanup, and real-time data feedback to further elevate efficiency and data quality.

Conclusion

The FLEX Series autosampler successfully automated the preparation of PAH calibration curves with excellent precision, linearity, and accuracy, significantly reducing hands-on time and potential for human error. This approach provides a robust solution for laboratories seeking to enhance productivity and meet regulatory requirements.

References

1. USEPA Method 8270D, Semivolatile Organic Compounds by Gas Chromatography/Mass Spectrometry, Revision 4, February 2007