Enhancing Throughput of Online SPE Analysis of Pesticides in Wastewater

Importance of the topic

Wastewater frequently contains trace levels of pesticides that can pose environmental and health risks. Efficient removal of matrix interferences and enrichment of analytes are essential for reliable quantification in complex samples. Online solid phase extraction (SPE) integrated with liquid chromatography–tandem mass spectrometry (LC-MS/MS) streamlines sample cleanup and concentration, reducing manual steps and increasing throughput.

Objectives and Study Overview

This study demonstrates how pairing two Agilent Multi-Cartridge Kits with the 1200 Infinity Series Online SPE Solution boosts sample throughput for pesticide analysis in wastewater. A set of 14 pesticides was spiked at 10 ng/L, and each cartridge in a 12-cartridge configuration underwent ten consecutive runs, totaling over 120 analyses. Key performance metrics—area and retention time repeatability, carryover, and cartridge lifetime—were evaluated.

Methodology

Samples of filtered wastewater were fortified with a mixture of 14 pesticides. The online SPE system used polymeric PLRP-S cartridges (2.1 × 12.5 mm) for enrichment. A large-volume injection (1,800 µL) loaded analytes onto the SPE cartridges, which were switched automatically via external valve drives. Elution onto a ZORBAX Eclipse Plus C18 analytical column followed a water/acetonitrile gradient with 0.1% formic acid. Detection was performed by triple quadrupole MS using optimized multiple reaction monitoring transitions.

Used Instrumentation

• Agilent 1200 Infinity Series Online SPE System with Flexible Cube and Starter Kits
• Two Agilent 1290 Infinity External Valve Drives (6-position/14-port valves)
• Agilent 1260 Infinity Binary Pump and Standard Autosampler
• Agilent 1290 Infinity Thermostatted Column Compartment
• Agilent 6400 Series Triple Quadrupole LC/MS with Jet Stream Technology
• Agilent MassHunter software suite for data acquisition, optimization, qualitative and quantitative analysis

Results and Discussion

The dual-Multi-Cartridge configuration permitted automated switching among 12 SPE cartridges without manual intervention, enabling over 120 sequential runs in under 48 hours. Relative standard deviations (RSD) for peak area were below 6% for aminocarb, 11.3% for thiabendazole, and 12.8% for metazachlor. Retention time RSD remained under 0.7% for all analytes. Carryover for thiabendazole was below 5% when assessed with blank injections; no significant carryover was observed for other compounds. Occasional signal fluctuations were attributed to matrix effects or cartridge performance, but overall robustness in a challenging wastewater matrix was confirmed.

Benefits and Practical Applications

• High throughput: Automated changeover among 12 cartridges supports extended sequences without downtime.
• Labor savings: Online SPE reduces manual handling compared to offline methods.
• Flexibility: System easily switches between direct injection and SPE modes.
• Robustness: Reliable performance for trace-level pesticide analysis in complex wastewater samples.

Future Trends and Opportunities

Advances in online SPE cartridge chemistries and valve automation may further increase throughput and selectivity for emerging contaminants. Integration with high-resolution mass spectrometry and data-processing algorithms will enhance multi-residue screening capabilities. Miniaturized valve manifolds and microfluidic approaches may reduce solvent consumption and footprint, aligning with green analytical chemistry goals.

Conclusion

The Agilent 1200 Infinity Online SPE solution with dual Multi-Cartridge Kits delivers a powerful platform for high-throughput, automated pesticide analysis in wastewater. The method achieves excellent repeatability, low carryover, and robust cartridge lifetimes, demonstrating practical utility for environmental monitoring and quality-control laboratories.

Reference

1. Naegele, E. Quantification of trace-level herbicides in drinking water by online enrichment with the Agilent 1200 Infinity Series Online-SPE Solution and Triple Quadrupole MS Detection. Agilent Technologies Application Note 5991-1738EN, 2013.
2. Naegele, E. Comparison of Direct Injection and Online SPE for Quantification by LC/MS of Trace-Level Herbicides in Water. Agilent Technologies Application Note 5991-2140EN, 2013.
3. Schuhn, B. High Volume Injection up to 5 mL with the Agilent 1200 Infinity Series Online SPE Solution for Highest Sensitivity. Agilent Technologies Technical Note 5991-3173EN, 2013.
4. Schuhn, B. Online SPE Multi-Cartridge Kit for Fast and Easy Method Development. Agilent Technologies Technical Note 5991-4005EN, 2014.
5. Yang, D.; Naegele, E. Detection of Basic and Acidic Pesticides and Herbicides at Trace Levels by Online SPE LC/MS in Drinking Water. Agilent Technologies Application Note 5991-4177EN, 2014.