1. Detected anions by other researchers
ION CHROMATOGRAPHY; AN EXAMINATION OF PORCINE LEACHATE TO IDENTIFY CHEMICAL MARKERS FOR CLANDESTINE GRAVES *Blom G.C.E.G. [1], Krens M.P.J. [2], Davidson A.R. [1], Cassella J.P. [1] & Pringle J.K. [3] [1] Forensic Science Department, Staffordshire University, U.K. [2] School of Life Sciences and Environmental Technology, Avans University, NL. [3] School of Physical and Geographical Sciences, Keele University, U.K.
Introduction
Preliminary Results
Previous research by Pringle et al showed significantly elevated conductivity levels in the leachate samples compared to the control samples. However no research has been conducted on the identification of the inorganic compounds which produced these high conductivity levels in the leachate. Additionally, not a lot of research has been conducted on the detection of inorganic compounds related to decomposition.
The aim of this project was to identify the inorganic anionic compounds present in those leachate samples and to determine if these ionic compounds are potentially able to locate clandestine graves.
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Detected anions by other researchers
Table 1: Detection of anionic compounds by other researchers. F-
CH3 CO2-
Cl-
NO2-
NO3-
HCO3-
HPO42-
SO42-
Vass (1992) X
EPA (1993)
Fernandez-Boy (1998)
Bommarito (2007)
Carter ( )
Aitkenhead – Peterson (2011)
STANIŠIĆ (2011)
Figure 2: Pie chart of % peak area for different anions.
Materials & Method
A domestic pig (Sus Domesticus Scrofa) was used as a proxy for a human cadaver due to the Human Tissue Act (2004) [Pringle et al ].
Soil moisture and decomposition fluids (leachate) pass into the lysimeter through the buried micro pore end.
The lysimeter was emptied two days prior to sample collection, then resealed and placed under partial vacuum pressure [see Pringle et al ].
The samples were collected, placed in labelled plastic bottles and frozen.
Control samples were taken from a lysimeter 10m from the grave site.
Figure 3: Graph of the detection of different anions over time since burial.
Conclusions
Table 3: First detection of different anions
Compound
Detected after weeks post burial
Chloride and sulphate 2
Nitrate and hydrogen phosphate 5
Acetate 6
Nitrite and hydrogen carbonate 26
Oxalate and unknown 2 ~
The highest ion concentrations detected:
Acetate (20g/l), Chloride (0,86g/l), Nitrate (0.15g/l), Hydrogen Carbonate (15g/l), Sulphate (0,14g/l).
Further work
Figure 1: photograph of the grave site.
Analyse the remaining Keele leachate and control samples.
Analyse the leachate samples from the other sites and compare the data with the data from the Keele samples.
Use a preservative to prevent degradation in the samples and standards. Also check the persevering abilities of putrescine and cadaverine as they are closely related to other preserving agents such as ethylenediamine.
This research is part of a PhD study entitled “Soil matrix interactions in a Taphonomic Environment: Forensic Considerations”.
The leachate samples were defrosted, diluted 10 times, filtered and injected in the ion chromatograph with the following equipment and conditions, see table 2.
Table 2: Ion chromatography equipment and conditions..
Parameter
Setting
Injection volume
0.5mL
Eluent
2L 4.5mM Na2CO mM NaHCO3
Flow
Isocratic 0,3mL/min
Regenerant
2L 7.2mN H2SO4
Guard column
Dionex RFIC IonPac® AG22 Guard
Separation column
Dionex RFIC IonPac® AS22 Column 2 x 250mm
Suppressor
AMMS-300 2mm anion micro membrane suppressor
Detector
DS5 Conductivity Detector
Run time
15min
References
Pringle, J. K., Cassella, J. P., Jervis, J.R. (2010) Preliminary soilwater conductivity analysis to date clandestine burials of homicide victims. Forensic Science International, 198,