Automating the Analysis of Mineral Oils in Water as according to ISO/DIS 9377-4 Using the Focus Sample Processing Robot

Importance of the Topic

The determination of mineral oil contamination in water is critical for environmental monitoring, regulatory compliance and public health protection. Traditional Freon-based extraction methods pose ecological and legislative constraints, driving the need for greener, automated workflows. Integrating gas chromatography (GC) approaches with robotics enhances throughput, consistency and reduces solvent consumption.

Objectives and Study Overview

This application note presents an automated adaptation of ISO/DIS 9377-4 for Total Petroleum Hydrocarbon (TPH) analysis in water. The goals are to compare the standard manual procedure with an automated Focus Sample Processing Robot and programmable large volume GC injector, evaluate performance metrics and demonstrate the environmental and economic advantages of automation.

Methodology

Samples are acidified to pH 2 and salted out with MgSO4 to enhance phase separation. Non‐polar analytes are extracted with hexane, followed by Florisil clean-up to remove polar interferences. The traditional ISO method concentrates the extract to 5 ml before a 1 µl GC injection. The automated workflow uses 20 ml vial extractions, sequential dispersive clean-up steps and direct large volume sampling (100 µl) into the GC injector without an evaporation step, under isothermal or temperature-programmed conditions to resolve C10–C40 hydrocarbons.

Used Instrumentation

• Focus Sample Processing Robot for automated extraction, clean-up and liquid handling
• ATAS Optic 2-200 programmable large volume injector for GC
• Finnigan GCQ mass spectrometer for quantification and speciation

Main Results and Discussion

• Precision: 2.5% RSD for six replicate injections (2 mg/l standard) and 2.7% RSD including extraction steps.
• Accuracy: 102.5% recovery for 1.6 mg/l oil spike in water.
• Sample tests: Distilled water spiked at 1.6 mg/l yielded 1.8 mg/l; lake water matrix spike returned 1.6 mg/l, confirming matrix robustness.
• Calibration linearity: 1–400 mg/l range by GC-MS; 0.1–40 mg/l demonstrated for spiked environmental samples.
• Cycle time: 60 minutes per sample, including extraction, clean-up and injection.

Benefits and Practical Applications

This automated ISO/DIS 9377-4 adaptation reduces solvent usage, mitigates human error and lowers labor costs compared to manual Freon methods. Large volume injection improves sensitivity and allows comprehensive hydrocarbon profiling for source identification. The workflow suits environmental laboratories, water quality monitoring and industrial QA/QC settings.

Future Trends and Potential Applications

Advances in robotic liquid handling and on-line clean-up columns will further streamline hydrocarbon analysis. Coupling with high-resolution mass spectrometry or comprehensive two-dimensional GC (GC×GC) can enhance speciation of complex mixtures. Emerging green solvents and miniaturized extraction formats will align with sustainability goals and regulatory drivers.

Conclusion

The automation of ISO/DIS 9377-4 using the Focus Sample Processing Robot and programmable large volume GC injector delivers reliable, precise and environmentally friendly TPH analysis in water. This approach matches or surpasses manual methods in performance while offering significant operational efficiencies.