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

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

3. Summary of talk Introduction Method Results Summary
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
introduction

4. Anatune Girton, Cambridge (March 2012) VAR for Agilent Gerstel
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. Enrich trace level analytes in water
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 (1-2%)

8. Correlation coefficient
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

9. NDMA and Metaldehyde very polar molecules
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 Method Results Summary
NDMA and Metaldehyde
Method
Automated Sample Preparation (focus on Gerstel instrumentation)
GC/MS/MS method
Results
Summary
introduction

14. Brand this set up - Multiflex
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 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
MetaldehydeSTD+IS_test_BiotageENV
4756
6115
6678
8082
5510
6795
MetaldehydeSTD+IS_test_DVBENV
959
857
926
919
880
779
MetaldehydeSTD+IS_test_C18
354
284
266
478
392.
MetaldehydeSTD+IS_test_CoconutCharcoal
6392
7722
6650
7737
5910
7172

16. Right MPS (2.5 ml Headspace syringe)
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 Method Results Summary
NDMA and Metaldehyde
Method
Automated Sample Preparation
GC/MS/MS method
Results
Summary
introduction

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

20. GC Methods NDMA Metaldehyde Different method
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
Different method
No reason in future to create one method
WAX

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

22. Optimised MRM Transitions for NDMA
Compound
Precursor Ion
Product Ion
CE (v)
NDMA-d6 (Quant)
80.1
50.1 5
NDMA-d6 (Qual)
46.1 15
NDMA (Quant)
74.1
44.1
NDMA (Qual)
42.1 20

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
Compound
Precursor Ion
Product Ion
CE (v)
Metaldehyde (Quant)
89.0
45.1 9
Metaldehyde (Qual)
43.1 42
Metaldehyde d16 (Quant)
98.1
50.1 12
Metaldehyde d16 (Qual)
46.1 39

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

28. Extracted Water - NDMA
Water spiked to build seven point calibration from 0.25 to 15 ng/l.
Correlation co-efficient of
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 – % Accuracy and precision of 1 ng/l & 10 ng/l standards (n=3)
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

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
X 25
concentration

35. Recovery and precision of water extractions (Metaldehyde)
Amount spiked (μg/L)
Amount detected (μg/L)
Mean SD
0.0015
% RSD
2.61
5.11
% Recovery
94.49
99.62

36. Developed two fully automated methods for NDMA and Metaldehyde
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 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