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

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

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

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

ADVANTAGES OF USING GC-MS  Fast analysis  Sensitive detector  Improved resolution  Derivitization not necessary  Correct identification possible

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

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

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

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

TIC OF CASE SAMPLE

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

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

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

LIBRARY MASS SPECTRUM OF PROPOXUR

LIBRARY MASS SPECTRUM OF PIRIMICARB

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

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

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

TIC WITH MASS SPECTRUM OF PROPOXUR

TIC WITH MASS SPECTRUM OF CASE SAMPLE

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

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

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.

THANKS