Agilent MicroLab Quant Calibration Software: Measure Oil in Water using Method IP 426

Importance of the Topic

Quantitative analysis of oil in water is critical for environmental monitoring and regulatory compliance. Fourier-transform infrared (FTIR) spectroscopy offers both sensitivity and selectivity for detecting hydrocarbons. Simplified workflows and reliable calibrations enhance routine laboratory operations and data integrity.

Objectives and Study Overview

This application note demonstrates the use of Agilent MicroLab Quant software to implement standard IP 426 for measuring aliphatic and aromatic hydrocarbons in water. The goals are to compare calibration approaches (Beer’s law, Classical Least Squares, Inverse Least Squares) and to establish a robust, user-guided method for accurate oil quantification.

Methodology and Instrumentation

The following steps were performed:

• Preparation of six aliphatic and six aromatic standard solutions (2–100 mg/L).
• Extraction of hydrocarbons from water using tetrachloroethylene.
• FTIR measurement on an Agilent Cary 630 spectrometer with a 10 mm quartz transmission cell.
• Spectra collected at 4 cm⁻¹ resolution, averaging 32 scans per sample.

MicroLab Quant guided users through spectrum selection, band definition at 2930, 2960, and 3030 cm⁻¹, and calibration model development.

Main Results and Discussion

Inverse Least Squares (ILS) delivered superior performance over simple Beer’s law:

• ILS cross-validation R² > 0.9999, standard error ~2.17 ppm.
• Beer’s law R² ≈ 0.997, standard error ~5.60 ppm.
• ILS accurately predicted an aromatic-only sample at –1.7 ppm versus Beer’s law overestimating at 3.63 ppm.

Real-time updates of calibration plots and numerical feedback enabled rapid optimization of band positions and calibration composition.

Benefits and Practical Applications

MicroLab Quant streamlines method development by:

• Offering guided workflows for multiple calibration algorithms.
• Allowing dynamic addition or removal of standards.
• Integrating directly with MicroLab PC for routine measurements.

This approach reduces analyst effort, minimizes user errors, and improves reproducibility for environmental and industrial testing.

Future Trends and Opportunities

Advancements may include:

• Enhanced multivariate algorithms for more complex matrices.
• Portable or field-deployable FTIR systems paired with simplified calibration tools.
• Cloud-based sharing of validated calibration models for collaborative quality control.

Conclusion

Agilent MicroLab Quant software simplifies and strengthens quantitative FTIR analyses of oil in water. By leveraging ILS, laboratories achieve highly accurate, rugged calibrations that seamlessly integrate into existing workflows.

References

IP 426: Standard Method for Measurement of Oil and Grease in Water by FTIR, Agilent Technologies, 2015.