THE MYSTERY BEHIND THE DEATH OF A BRIDE

1
THE MYSTERY BEHIND THE DEATH OF A BRIDE

• By
• R.S. Verma, R.M. Tripathi and A.K.Dalela
• Central Forensic Science Laboratory,
• DFS, MHA, Govt. of India, Sec.36-A, Chandigarh

2
TRENDS OF POISONING

• In Northern India, 25 cases of poisoning relate
  to insecticides
• Carbamate constitutes a major share
• Correct identification of insecticides is a
  challenge to toxicologists

3
PROBLEMS WITH THE SAMPLES

• The quality and quantity of insecticides
  available in the biological tissues/fluids is
  usually very low
• Longer period in between ingestion and collection
  of samples further reduces availability of
  insecticides

4
ROUTINE TECHNIQUES- LIMITATIONS

• Colour tests lack specificity
• TLC also lacks specificity
• Rt parameter in GC HPLC being non-specific
  only enhances the confidence level for
  identification

5
ADVANTAGES OF USING GC-MS

• Fast analysis
• Sensitive detector
• Improved resolution
• Derivitization not necessary
• Correct identification possible

6
HISTORY OF THE CASE

• A newly married lady admitted in the hospital
  after suspected poisoning
• Stomach wash preserved in the hospital
• Doctors suspected organophosphorus/ celphos
  poisoning
• Lady died after 62 hours hospitalisation

7
Contd.

• Report of viscera did not indicate any
  poison(Chemical examination lab.)
• CFSL, Chandigarh received only stomach wash (15
  ml) on order of Pb. Hr. High Court
• Sample size was very small

8
THIN LAYER CHROMATOGRAPHY

• TLC gave a faint black spot with Tollens reagent
• May be due to carbamate/ organophosphorous
  insecticide
• Gave negative results for organophosphorous
  insecticide

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GC-MS ANALYSIS

• Capillary column DB-5(30m)
• Column Temp. 80oC-250oC
• Temp. Programming 8oC/min
• Injector Temp. 250oC
• Detector Temp. 250oC
• Ion Source Temp 200oC

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TIC OF CASE SAMPLE
11
Contd.

• Base peak 110
• Mass spectrum contained three characteristic ions
  with m/z 110, 81152
• Three ions not enough to form opinion

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WHICH CARBAMATES CONTAIN THREE IONS? (110, 152
81)

• Carbofuran 221,165,149,131,122,103,
• 91,77,57
• Carbaryl 201,167,157,144,127,115,
• 101,89,72,57
• Propoxur 209,152,137,121,110,92,81,
• 64,58
• Pirimicarb 238,166,152,138,123,110,
• 109,72,53

13
Contd..

• Methicarb 225,168,153,139,121,109,91
• 77,58
• Methomyl 162,127,105,88,71,58
• Aldicarb 144,115,100,86,76,69,58

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LIBRARY MASS SPECTRUM OF PROPOXUR
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LIBRARY MASS SPECTRUM OF PIRIMICARB
16
Contd

• Only propoxur contains ions 110, 152 81
• Base peak is 110 ions 152 81 are with about
  15 to 20 abundance
• Pirimicarb contains only two ions 110 152 with
  less than 10 abundance
• Base peak in pirimicarb in 166 and also ion with
  m/z 81 is absent

17
Contd

• On the basis of the presence of three
  characteristic ions with m/z 110, 152 and 81 and
  their abundance, the probable carbamate remains
  to be propoxur
• Other ions present in mass spectrum of propoxur
  such as 92,82 64 were found to be absent in the
  mass spectrum of case sample
• Absence of remaining ions restricts
  identification of insecticide propoxur in case
  sample

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Contd..

• To corroborate findings TLC of standard propoxur
  with varying amount was conducted under similar
  conditions
• Mass spectra of extracted standard propoxur also
  contained ions at 110, 152 and 81 with base peak
  and 110

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TIC WITH MASS SPECTRUM OF PROPOXUR
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TIC WITH MASS SPECTRUM OF CASE SAMPLE
21
Contd

• Retention time of TIC of propoxur and its ions
  with m/z 110, 152 and 81 is 1.83 minutes
• Retention time of TIC of case sample ions 110,
  81 152 is also 1.83 minutes
• TIC of case sample and extracted standard
  propoxur shows that all the three ions present
  have originated from the same peak having similar
  retention time

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CONCLUSION

• No doubt, eight peak mass spectrum is required
  for the identification of the compound
• In this study, identification of the compound
  could be possible with the help of three ions
  only
• In toxicological samples, quality and quantity of
  insecticides can be very low, where it will be
  difficult to get eight peak mass spectrum

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Contd

• The method stated above focussing the
  characterization of most abundant ions and also
  considering their retention time matching with
  TIC of the substance can be safely used to
  identify unknown substance including carbamates
• Hence, analysis confirms poison in gastric lavage
  of lady. Thus, solving mystery of her death.

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• THANKS