Direct Injection and Online SPE LC/MS/MS for the Determination of Pharmaceuticals and Personal Care Products (PPCPs) in Water Samples - Using the Agilent InfinityLab Online SPE Solution

Importance of the Topic

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants frequently detected at trace levels in environmental and drinking waters. Their presence, even at nanogram-per-liter concentrations, raises concerns about ecological impacts and human health. Regulatory agencies are tightening limits for water quality, driving the development of highly sensitive and automated analytical methods.

Objectives and Study Overview

This study aimed to develop and compare two workflows for PPCP analysis in water: direct injection of small sample volumes and online solid-phase extraction (SPE) with large volumes. Using the Agilent InfinityLab Online SPE solution combined with an Agilent 6470A Triple Quadrupole LC/MS system, researchers evaluated method precision, sensitivity, and applicability to real surface water samples.

Methodology

The two workflows were configured on a single LC/MS platform with automated switching:

• Direct Injection: 100 µL injections onto an InfinityLab Poroshell 120 EC-C18 column.
• Online SPE: 1.5 mL injections loaded on a PLRP-S cartridge, back-flushed onto the same analytical column.

Samples were spiked at low ng/L levels in tap, lake, and canal waters acidified with 0.1 % formic acid. A gradient elution with ammonium formate/formic acid and acetonitrile was used. Quantification relied on dynamic multiple reaction monitoring (MRM).

Used Instrumentation

The LC/MS setup included:

• Agilent 1290 Infinity II High Speed Pump (analytical)
• Agilent 1260 Infinity II Quaternary Pump (SPE)
• Agilent 1290 Infinity II Multisampler with 100 µL head
• Agilent 1290 Infinity Valve Drive and Quick Change 2-Position/6-Port valve
• Agilent 1290 Infinity Multicolumn Thermostat and Flexible Cube
• Agilent Online SPE Starter Set (800 bar) and Direct Inject Kit (1,300 bar)
• SPE cartridges: PLRP-S, 2.1 × 12.5 mm, 15–20 µm
• Analytical column: Poroshell 120 EC-C18, 2.1 × 100 mm, 2.7 µm
• Agilent 6470A Triple Quadrupole LC/MS with Jet Stream ESI source

Main Results and Discussion

Chromatographic profiles remained consistent between modes, with a three-minute retention shift in online SPE due to sample loading time. Injection precision (RSD) was below 10 % for most compounds in both workflows. Online SPE delivered a 5- to 50-fold improvement in limits of detection (down to < 0.1 ng/L) and steeper calibration slopes, while maintaining peak shape. In real surface waters, online SPE enabled quantification of PPCPs—such as valsartan and sulfadimethoxine—that were near or below detection by direct injection. Recoveries ranged 70–120 %, acceptable given the diverse chemistries and a single loading condition.

Benefits and Practical Applications

Automated switching between direct injection and online SPE increases laboratory throughput and flexibility. Online SPE significantly enhances sensitivity and selectivity, reducing matrix interferences without manual cleanup. The single-platform approach simplifies method transfer and routine monitoring of trace contaminants in environmental and drinking waters.

Future Trends and Applications

Potential developments include:

• Expansion to a broader range of emerging contaminants (e.g., PFAS, pesticides).
• Integration with high-resolution MS for non-target screening.
• Miniaturization of SPE cartridges for lower solvent use and greener workflows.
• High-throughput configurations for multi-site monitoring programs.
• Machine-learning–driven method optimization and data analysis.

Conclusion

The Agilent InfinityLab Online SPE solution coupled to a 6470A LC/MS offers an automated, robust, and highly sensitive method for PPCP determination in water. It outperforms direct injection for trace-level detection while preserving chromatographic integrity. The workflow is well suited for environmental and drinking water monitoring under evolving regulatory requirements.

References

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2. US EPA Method 1694 (2007). Pharmaceuticals and Personal Care Products in Water, Soil, Sediment, and Biosolids by HPLC/MS/MS.
3. Directive 2013/39/EU of the European Parliament and of the Council amending Directives 2000/60/EC and 2008/105/EC concerning priority substances in water policy.
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