Automated%20SPE%20for%20NDMA%20and%20Metaldehyde%20in%20water%20using%20GC-QqQ

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

• Dan Carrier, Applications Chemist

www.anatune.co.uk
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Purpose of this presentation

• show how methods NDMA Metaldehyde fully
  automated using Gerstel and Agilent
  instrumentation

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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

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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

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

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Twister SBSE

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

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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)

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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
Correlation coefficient Calibration after extraction
Monuron 0.9989
Isoproturon 0.9995
Diuron 0.9997
Linuron 0.9984
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Introduction

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

NDMA
Metaldehyde
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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.

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Metaldehyde

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

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NDMA

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

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Summary of talk

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

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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

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ITSP (Instrument Top Sample Preparation)

• Typically 15-25 mg sorbent
• Metaldehyde
• Biotage ENV (as in literature)
• NDMA Coconut charcoal

  Metaldehyde Results Metaldehyde_d16 (ISTD) Results
Name Resp. Area
Metaldehyde_DCM_Standard4 5202 6189
MetaldehydeSTDIS_test_BiotageENV 4756 6115
MetaldehydeSTDIS_test_BiotageENV 6678 8082
MetaldehydeSTDIS_test_BiotageENV 5510 6795
MetaldehydeSTDIS_test_DVBENV 959 857
MetaldehydeSTDIS_test_DVBENV 926 919
MetaldehydeSTDIS_test_DVBENV 880 779
MetaldehydeSTDIS_test_C18 354 284
MetaldehydeSTDIS_test_C18 354 266
MetaldehydeSTDIS_test_C18 478 392.
MetaldehydeSTDIS_test_CoconutCharcoal 6392 7722
MetaldehydeSTDIS_test_CoconutCharcoal 6650 7737
MetaldehydeSTDIS_test_CoconutCharcoal 5910 7172
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• 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
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• 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

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Summary of talk

• Introduction
• NDMA and Metaldehyde
• Method
• Automated Sample Preparation
• GC/MS/MS method
• Results
• Summary

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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
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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

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Multiple Reaction Monitoring
74.1
44.1
Direct comparison at NDMA at 0.125 ng/ml
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Optimised MRM Transitions for NDMA
Compound Precursor Ion Product Ion CE (v)
NDMA-d6 (Quant) 80.1 50.1 5
NDMA-d6 (Qual) 80.1 46.1 15
NDMA (Quant) 74.1 44.1 5
NDMA (Qual) 74.1 42.1 20
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EI Ionisation Experiments
Varying from 10 to 80 eV
70 eV
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Varying Ion Source Temperature
Varying between 150 350 C
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Optimised MRM Transitions for Metaldehyde
Compound Precursor Ion Product Ion CE (v)
Metaldehyde (Quant) 89.0 45.1 9
Metaldehyde (Qual) 89.0 43.1 42
Metaldehyde d16 (Quant) 98.1 50.1 12
Metaldehyde d16 (Qual) 98.1 46.1 39
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Summary of Method development

• Metaldehyde method developed within 2 weeks
• NDMA over 3 months
• Contamination issues
• Exposing LC/MS grade
• water to light!

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Summary of talk

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

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Extracted Water - NDMA
Water spiked to build seven point calibration
from 0.25 to 15 ng/l. Correlation co-efficient
of 0.9995.
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NDMA comparison with blank

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

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Standard Extracted Water 10 ng/l
NDMA
NDMA-d6
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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)

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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 (n3)

NDMA 1 ng/l 10 ng/l
     
Mean ng/l result 0.997 10.329
SD 0.005 0.266
RSD 0.5 2.6
Ave. Corrected Recovery 100.2 102.7
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40 ng/l Metaldehyde extracted standard comparison
with blank

• Detection limit approx 2 ng/l (based on signal to
  noise from this standard)

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Extracted Water - Metaldehyde
Water spiked to build seven point calibration
from 40 to 800 ng/l. Correlation co-efficient of
0.9993.
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Recovery and precision of water
extractions(Metaldehyde)
Amount spiked (µg/L) 0.06080 0.70400
Amount detected (µg/L) 0.05734 0.63858
0.05721 0.71908
0.06000 0.70449
0.05628 0.72256
0.05641 0.72204
Mean 0.05745 0.70135
SD 0.0015 0.035856
RSD 2.61 5.11
Recovery 94.49 99.62
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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

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Acknowledgements

• Anatune
• Paul Roberts
• Anais Maury
• Matthew Carson

• Rick Youngblood
• Ken Brady

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• Any Questions?

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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