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Automated SPE for NDMA and Metaldehyde in water using GC-QqQ

Automated SPE for NDMA and Metaldehyde in water using GC-QqQ. Dan Carrier, Applications Chemist. www.anatune.co.uk. Purpose of this presentation. “show how methods NDMA & Metaldehyde fully automated using Gerstel and Agilent instrumentation”. Summary of talk. Introduction

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Automated SPE for NDMA and Metaldehyde in water using GC-QqQ

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  1. Automated SPE for NDMA and Metaldehyde in water using GC-QqQ Dan Carrier, Applications Chemist www.anatune.co.uk

  2. Purpose of this presentation “show how methods NDMA & Metaldehyde fully automated using Gerstel and Agilent instrumentation”

  3. Summary of talk • Introduction • Background NDMA and Metaldehyde • Why trace level method for both analytes • Method • Automated Sample Preparation • Chromatographic method using GC/MS/MS • Results • ~1 ng/l NDMA in extracted water • ~2 ng/l Metaldehyde in extracted water • Summary • Good overview of system

  4. Anatune • Girton, Cambridge (March 2012) • VAR for Agilent • GC and LC products • MSD, QqQ, QTOF • Gerstel • MPS – DHS, Twister, ITSP • Focus - Sell and Support Solutions • Wide number of industries - Environmental, Food and Flavours, Petrochem, Pharmaceutical, Forensic, and Clinical

  5. Dual Head MPS Solution with LC/UV • Formaldehyde and acetaldehyde in air

  6. Twister SBSE • Enrich trace level analytes in water • Twisters made PDMS (ethylene glycol) • Adsorption based on lipophibicity • Log K o/w

  7. Twister SBSE – PAH solution • 100 ml water samples (2 hours) • Dried and placed in TDU tubes • SIM 16 PAH (0.02 ug/l to 1 ug/l) • Acenaphthene 0.999 (1-2%)

  8. ITSP & LC/MS/MS • Diurons in water • Enrich 10 ml • Elute in 0.8 ml Chromatogram Monuron (quantifier transition) in standard 0.40 μg/L after extraction

  9. Introduction • NDMA and Metaldehyde very polar molecules • Enrichment methods from water problematic • Developed two separate automated methods Metaldehyde NDMA

  10. Harm - NDMA • Industrial by-product many processes • IARC (International Agency for Research on Cancer) NDMA is probably carcinogenic to humans • WHO Guideline limit NDMA of 100 ng/l in drinking water.

  11. Metaldehyde • Widespread Pesticide • Regulatory limit 100 ng/L in drinking water

  12. NDMA • Initial method on MSD 5975C (before QqQ) • Method Detection limit 25 ng/L • AS 119 • Needed to get better sensitivity but also selectivity!

  13. Summary of talk • Introduction • NDMA and Metaldehyde • Method • Automated Sample Preparation (focus on Gerstel instrumentation) • GC/MS/MS method • Results • Summary

  14. Automated Sample Prep 2.5 ml HS Syringe 10 ul Syringe • Brand this set up - Multiflex • Consists of Dual Head MPS • Thermal Desorption unit – Cold Inlet System - PTV

  15. ITSP (Instrument Top Sample Preparation) • Typically 15-25 mg sorbent • Metaldehyde • Biotage ENV (as in literature) • NDMA – Coconut charcoal

  16. Coconut Charcoal ITSP cartridges (NDMA) ENV (Metaldehyde) Right MPS (2.5 ml Headspace syringe) Conditioned 750 µl dichloromethane 1000 µl of methanol Equilibrated 2000 µl of HPLC grade water Load 10 ml of sample (in water) Dried 15 minutes Eluted 400 ul dichloromethane Left MPS (10 ul) Large Volume injection X 25 concentration

  17. Large Volume Injection– removing DCM boiling point 40 °C, Metaldehyde and NDMA both exceed 100 °C Inlet kept at 10 °C (peltier cooled) Slow injection speed at 0.5 ul/s (to remove DCM) ramped to 250 °C (12 °C /s) NDMA (similar for Metaldehyde) - Glass beads liner gave best results

  18. Summary of talk • Introduction • NDMA and Metaldehyde • Method • Automated Sample Preparation • GC/MS/MS method • Results • Summary

  19. Agilent GC/QqQ • Agilent 7890A GC • Agilent 7000 GC/MS triple quad • Increased Sensitivity and Selectivity Direct comparison at NDMA at 0.125 ng/ml (without extraction) Single Ion Monitoring Multiple Reaction monitoring

  20. GC Methods • NDMA • DB-WAX 30 m x 250 μm x 0.5 μm • Thermal gradient from 35 deg C to 240 deg C over 10 minutes • Metaldehyde • DB5 30m x 250 μm x 0.25 μm • Thermal gradient from 35 deg C to 250 deg C over 10 minutes • Different method • No reason in future to create one method • WAX

  21. Multiple Reaction Monitoring 74.1 44.1 • Direct comparison at NDMA at 0.125 ng/ml

  22. Optimised MRM Transitions for NDMA

  23. EI Ionisation Experiments Varying from 10 to 80 eV 70 eV

  24. Varying Ion Source Temperature Varying between 150 & 350 °C

  25. Optimised MRM Transitions for Metaldehyde

  26. Summary of Method development • Metaldehyde method developed within 2 weeks • NDMA over 3 months • Contamination issues • Exposing LC/MS grade water to light!

  27. Summary of talk • Introduction • NDMA and Metaldehyde • Method • Automated Sample Preparation • GC/MS/MS method • Results - NDMA • Summary

  28. Extracted Water - NDMA Water spiked to build seven point calibration from 0.25 to 15 ng/l. Correlation co-efficient of 0.9995. X 25 concentration

  29. NDMA comparison with blank 1 ng/l NDMA in LC/MS grade water with blank (extracted LC/MS grade water) - around detection limit

  30. Standard Extracted Water 10 ng/l NDMA NDMA-d6

  31. Absolute Recovery Absolute recovery of NDMA established at 1 ng/l & 10 ng/l spikes 1 ng/L NDMA – Absolute recovery 55 % (% RSD 9.2) 10 ng/l NDMA – Absolute recovery 61 % (% RSD 2.6) 40 ng/l NDMA-d6 – Absolute recovery 56 % (% RSD 7.9)

  32. Recovery and precision of water extractions Calculated accuracy of all calibration points 86.5 – 107.1 % Accuracy and precision of 1 ng/l & 10 ng/l standards (n=3)

  33. 40 ng/l Metaldehyde extracted standard comparison with blank Detection limit approx 2 ng/l (based on signal to noise from this standard)

  34. Extracted Water - Metaldehyde Water spiked to build seven point calibration from 40 to 800 ng/l. Correlation co-efficient of 0.9993. X 25 concentration

  35. Recovery and precision of water extractions(Metaldehyde)

  36. Summary • Developed two fully automated methods for NDMA and Metaldehyde • Good linearity and recovery for NDMA and Metaldehyde • Detection limit (after extraction) • NDMA between 0.5 to 1 ng/l • Metaldehyde approx 2 ng/l

  37. Acknowledgements • Anatune • Paul Roberts • Anais Maury • Matthew Carson • Rick Youngblood • Ken Brady

  38. Any Questions?

  39. Additional Work on MRM method • Work was completed to assess the impact of running MS1 & MS2 in unit, wide and widest resolution modes. • Increased sensitivity as resolution decreased, but possibility of interferences increases • Unit 0.7 amu at half height • Wide 1.2 amu at half height • Widest 2.5 amu at half height • Default QQQ Collision Cell conditions for Collision Cell and Quench Gas

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