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 Tollen’s reagent  May be due to carbamate/ organophosphorous insecticide  Gave negative results for organophosphorous insecticide

9. GC-MS ANALYSIS  Capillary columnDB-5(30m)  Column Temp.80 o C-250 o C  Temp. Programming8 o C/min  Injector Temp.250 o C  Detector Temp.250 o C  Ion Source Temp200 o C

10. TIC OF CASE SAMPLE

11. Contd…. i)Base peak 110 ii)Mass spectrum contained three characteristic ions with m/z 110, 81&152 iii)Three ions not enough to form opinion

12. WHICH CARBAMATES CONTAIN THREE IONS? (110, 152 & 81) Carbofuran221,165,149,131,122,103, 91,77,57 Carbaryl201,167,157,144,127,115, 101,89,72,57 Propoxur 209,152,137,121,110,92,81, 64,58 Pirimicarb238,166,152,138,123,110, 109,72,53

13. Contd…….. Methicarb225,168,153,139,121,109,91 77,58 Methomyl162,127,105,88,71,58 Aldicarb144,115,100,86,76,69,58

14. LIBRARY MASS SPECTRUM OF PROPOXUR

15. 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

18. 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

19. TIC WITH MASS SPECTRUM OF PROPOXUR

20. 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

22. 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

23. 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.

24. THANKS