Evaluation training on residue analysis of pesticides

1
Evaluation training on residue analysis of
pesticides
Guido van der Weg Wim Traag
2
Observations Monday

• Tuning of system looks all right but
• Small leak in the system
• Used liner contains glass wool ?
  adsorption/degradation
• After replacement of liner (part nr 5181-3315)
  system was tuned en tested with HCB
• Sensitivity ok
• Peak width gt 10 seconds
• Conclusion column was not suited
• Column replaced

3
No air leakage
4
Air leak !!!Ratio N2 / O2 should be 41
5
Tuesday

• Still small air leakage
• Ferrule on injector replaced (graphite ? vespel)
• Ferrule on interface still has to be changed
• Ratio N2 / O2 is 71 instead of 41 indicating
  helium contaminated with N2 ? no problem

6
Tune file (Air should be lt 5 )
7
Tuesday

• Application of Quechers method
• Five samples
• Spiking levels 0, 250 and 1000 ppb
• Samples have also been spiked with RIKILT mix at
  50 ppb
• Use of tubes of 15 ml is suitable
• Take 2 ml sample add 300 mg MgSO4 and 50 mg PSA
• Use standard centrifuge (4000 rpm)
• Criteria ? separation between liq and solid

8
Tuesday

• On basis of full scan analysis SIM method was set
  up
• Five windows
• Four ions per component
• One Internal standard (might be extended or
  changed)
• I.S preferable 13C labeled pesticide
• In future more compounds can eaily be added

9
SIM 1
10
SIM 2
11
SIM 3
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Wednesday

• Checking GC-MS
• Stability of RT
• Stability of Sensitivity
• System was working nicely
• Initialization of GPC
• GC-MS was started again for
• Two samples cleaned with GPC
• full scan analysis of a few samples

13
Thursday

• Data processing of analyzed samples
• Set up of calibration/quantification file on
  basis
• RT
• One ion for Quantification
• Three ions for identification
• Remark
• Method have to be adjusted for ion 339 instead of
  241 for endoslufan (Friday)
• Upper and lower limit have to be expanded
  (Friday)
• Addition of standards have been shown
• Reporting methods have been demonstrated

14
Thursday

• Results obtained with SIM method and automatic
  data processing look promising
• Quechers method gives good chromatograms
  (interfernces are limited
• Only interference for a-endosulfan
• Recoveries look good
• Deviating results for samples spiked with RIKILT
  standard
• Remark Antalya mix should be based on reference
  standards or ha to be prepared again
• After modification of processing methods samples
  can be reprocessed by colleague of Antalya and
  results have to be studied carefully

15
Thursday

• Best data report is
• Detailed giving information about
• Concentration of pesticide in sample
• Peak shape (top of ions should be equal)
• Ratio of qualifier ions

16
Thursday

• PM has been done by Ozlem
• Standards and two samples have been analyzed
  again
• GPC system have been tested with
• Sunflower oil and Toluene
• Conclusion system ok
• Test in future with pesticide collect
• Main fraction e.g. 14 -29 minutes
• First fraction e.g. 13-14 minutes
• Last fraction e.g. 29-30 minutes

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Thank you for your hospitality

• Wim.Traag_at_wur.nl
• Guido.vanderweg_at_wur.nl