A fully automated and quantitative method for Metaldehyde in water using GC/QqQ

Significance of the Topic

Metaldehyde is widely used as a molluscicide in agriculture and persistent in water bodies Its moderate solubility leads to contamination of surface waters and potential breaches of regulatory thresholds in drinking water The UK limit is 0.1 microgram per liter Ensuring reliable monitoring of trace levels of metaldehyde is critical for environmental and public health

Objectives and Study Overview

The aim was to establish a fully automated solid phase extraction SPE protocol coupled to gas chromatography with triple quadrupole detection GC QqQ for quantitative analysis of metaldehyde in water This study demonstrates automation of SPE using instrument top sample preparation ITSP on a multipurpose sampler MPS and detection via multiple reaction monitoring MRM for enhanced selectivity and sensitivity

Methodology and Instrumentation

The extraction was performed on a dual head sampler The right head used a 2.5 milliliter headspace syringe to condition a 20 milligram ENV SPE cartridge with dichloromethane methanol and water Following sample loading the cartridge was dried under nitrogen and eluted with dichloromethane The left head injected a 10 microliter aliquot of the extract into a cooled injection system The GC QqQ system comprised major components

• Gerstel Multipurpose Sampler MPS 2 XL dual head
• Gerstel Cooled Injection System CIS 4
• Instrument Top Sample Preparation ITSP cartridges
• Agilent 7890A Gas Chromatograph
• Agilent 7000 Triple Quadrupole Mass Spectrometer

Chromatographic conditions included a large volume injection by programmable temperature vaporizing solvent vent using a Tenax liner A DB 5MS column 30 meters by 0.25 millimeter by 0.25 micrometer was operated with a thermal gradient from 50 to 300 degrees Celsius The mass spectrometer was operated in electron impact mode monitoring two transitions per analyte For metaldehyde transitions were m/z 89 to 45 and 89 to 43 Internal standard metaldehyde d16 transitions were m/z 98 to 50 and 98 to 46

Main Results and Discussion

Calibration over a range of 0.04 to 0.8 microgram per liter yielded a correlation coefficient of 0.999 Theoretical detection limit was 0.002 microgram per liter Recovery studies at 0.06 and 0.7 microgram per liter showed mean recoveries of 94.5 and 99.6 percent with relative standard deviations of 2.6 and 5.1 percent respectively Chromatograms of blanks and low calibration levels confirmed absence of interferences and clear analyte peaks

Benefits and Practical Applications

The automated workflow reduces manual handling and improves reproducibility High selectivity and low detection limits allow compliance testing of drinking water and environmental monitoring The method supports high throughput routine analysis in laboratory settings

Future Trends and Applications

Future work will apply the method to real surface and groundwater samples from diverse sources Standard addition approaches will evaluate matrix effects and method robustness Adaptation of this automated SPE GC QqQ platform to other pesticides and emerging contaminants may further expand its utility

Conclusion

A fully automated SPE GC QqQ method for metaldehyde in water has been developed demonstrating excellent sensitivity linearity and recovery The approach meets regulatory requirements and offers a streamlined solution for routine environmental analysis

References

Anais Maury Dan Carrier and Paul Roberts A fully automated and quantitative method for Metaldehyde in water using GC QqQ Chromatography Technical Note No AS123 Anatune Ltd 2012