Transfer and Speed-up of Methods to Fused-Core Particle Columns – EPA Method 1694

Significance of the topic

The occurrence of pharmaceuticals and personal care products (PPCPs) in drinking water has become a major environmental and public health concern. Reliable analytical methods are required to detect trace levels of these compounds in various matrices. EPA Method 1694 establishes a robust protocol for simultaneous quantitation of over 70 PPCPs using solid‐phase extraction (SPE) coupled to LC‐MS/MS. Accelerating this workflow without sacrificing resolution can improve laboratory throughput and reduce operational costs.

Objectives and study overview

This study evaluates the transfer of Group 1 PPCP assays from conventional porous‐particle HPLC columns to advanced fused‐core (superficially porous) particle columns. Key goals include:

• Maintaining or improving chromatographic resolution of critical analyte pairs
• Reducing analysis time and system backpressure
• Validating performance against sub-2 µm UHPLC columns under typical instrument pressure limits

Methodology and instrumentation

Solid‐phase extraction: Supelco Select HLB cartridges (500 mg) conditioned with methanol and acidified water. 500 mL spiked drinking water samples (pH 4) were loaded at 10 mL/min, dried, and eluted with 50:50 MeOH:ACN.

LC-MS/MS conditions:

• Instrument: Applied Biosystems 3200 QTRAP with turbo-ion‐spray ESI (+), MRM detection
• Column: Ascentis Express C18 fused-core, 10 cm × 2.1 mm, 2.7 µm
• Mobile phases: A = 0.1% formic acid + 0.1% NH4HCO2 in water; B = 50:50 MeOH:ACN; gradient elution over 33 min
• Flow: 150–300 µL/min; temperature: 40 °C; injection: 5 µL

Main results and discussion

• The fused-core column delivered equivalent theoretical plate counts (N) for late‐eluting naphthalene with a 5-fold shorter column length and moderate pressures (< 250 bar).
• Throughput improvements ranged from 4- to 15-fold compared to a 5 µm C18 column, with baseline separation of critical analyte pairs maintained.
• At fixed pressure limits of conventional HPLC systems, fused-core columns matched or exceeded the performance of sub-2 µm UHPLC columns by allowing longer columns and higher flow rates.
• A full mix of 55 MRM transitions for Group 1 PPCPs showed robust peak shapes and retention reproducibility; some β-lactam analytes exhibited weaker recovery, suggesting further SPE optimization.

Benefits and practical applications of the method

• Enables rapid turnaround of environmental water analyses without requiring UHPLC hardware upgrades
• Reduces instrument wear and maintenance by operating at pressures within conventional HPLC limits
• Improves laboratory throughput for QA/QC and research applications in environmental monitoring

Future trends and possibilities for use

• Expansion of fused-core column applications to other EPA methods (e.g., hormones, steroids).
• Development of optimized SPE phases for challenging analyte classes, such as β-lactams.
• Integration with automated sample preparation and multiplexed LC-MS platforms for high-throughput screening.
• Exploration of new superficially porous particle chemistries to further enhance selectivity and speed.

Conclusion

Fused-core particle columns offer a compelling alternative to sub-2 µm UHPLC columns for EPA Method 1694. They provide high efficiency and significant reductions in analysis time at moderate pressures compatible with existing HPLC systems. This approach facilitates method transfer, reduces operational complexity, and supports rapid environmental monitoring of PPCPs.

Instrumentation

• Applied Biosystems 3200 QTRAP LC-MS/MS
• Ascentis Express C18 fused-core columns (2.7 µm, 10 cm × 2.1 mm)
• Supelco Select HLB SPE cartridges (500 mg/6 mL)

References

Mauney E., Brandes H.K., Campbell W.H., Way W.K., Henry R.A., Bell D.S., Santasania C.T. Transfer and Speed-up of Methods to Fused-Core Particle Columns – EPA Method 1694. Supelco, Sigma-Aldrich, Bellefonte, PA, 2009.