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LABORATORY PERFORMANCE IN THE FORENSIC TOXICOLOGY INTERLABORATORY COMPARISON PROJECT, 2003


INCHAI, W., SUKREETA, S., SRIPAORAYA, K., PERMPOON, P.,
ARPADNOK, D., BOONYAWONGVIROT, J. and PAVITTRANON, S.


Nakhon Ratchasima Regional Medical Sciences Center and National Institute of Health,
Department of Medical Science, Ministry of Public Health, Thailand.


Abstract

      The Department of Medical Sciences ( DMSc) has initiated the Forensic Toxicology Interlaboratory Comparison (FTIC) project since 1990. The project has been intramural, only DMSc central laboratory and the 12 Regional DMSc laboratories were the participants. In 2003, we invited the laboratories outside DMSc to enroll, total 17 laboratories.

      The focus of the project is on qualitative analyses on unknown samples which background history of poisonning cases. All samples were prepared with spiked chemicals. In 2003, the Nakhon Ratchasima DMSc Regional Medical Sciences Center is reponsible for organising the project. The laboratories received 3 unknown samples and allowed 30 days for reporting the results. The methods utilized by laboratories were chemical testing, TLC, spectrophotometer, GC, HPLC, Immunoassay, and TDx.

      There is some notable similarity in the correct results for the 15 laboratories that participated in the project. One laboratory reported quantitatively. It is also fare to specify that the unknown samples were only single contamination which is easier than the mixture of chemicals in real life with matrix interferences. None of the laboratory needs sophisticated equipment such as GC-MS for analyzing the samples.


Introduction

      The Department of Medical Sciences (DMSc) has initiated the Forensic Toxicology Interlaboratory Comparison (FTIC) project since 1990. The project has been intramural, only DMSc central laboratory and 12 Regional Medical Science Center (RMSc) were the participants. In 2003, was invited the laboratory outside DMSc to enroll and Nakhorm Ratchasima Regional Center in the Northern part of Thiland is reponsible for organising the project. The laboratories received 3 unknown samples once and allowed 30 days for reporting the results.

      The aim of this project is to help Forensic Science Laboratory to have quality control procedure for monitoring the validity of tests and calibrations undertaken. This monitoring may include the participation in interlaboratory comparisons or proficiency testing programs. By this mean a laboratory can provide evidence of its competence to its clients.

Sample Preparation
      Unknown forensic toxicology samples which backgrond history of poisonning cases were prepared with spiked chemicals. The homogenised material was shipped to each laboratory.

           Unknown I Nor- Mice (Tri zinc phosphate, 80% PW) 100 grams mixed to coffee 2,460 grams.
           Unknown II Diazepam Tablet, 10 mg (5 tablet) diluted
with beer 3,200 milliliters.
           Unknown III Bendiocarb 1 % w/w mixed with rice.


Result

Unknown
Mixture
Result From 17 Laboratories
 
 
Correct
Incorrect
incomplete
Not Report
I
Zinc phosphide
13
1
1
2
II
Diazepam
16
-
-
2
III
Bendiocarb
14
1
1
1


Methods of 17 Laboratories

Unknown I
Unknown II
Unknown III
Atomic Absorption Spectrometry Extraction Extraction
Silver nitrate testing Thin Layer Chromatography Thin Layer Chromatography
Gutzeit's Test Spectrometry Spectrometry
Reinsch's Test TDx Gas Chromatography, NPD
Molybdinum blue Test High Performance Liquid Chromatography  
Thin Layer Chromatography Immono Assay  


Summary

      This report describes the results of the ongoing study of forensic toxicology laboratory in Thailand. The forensic toxicology laboratories currently in operation constitute the majority in Thailand national laboratory system for forensic toxicology analyses other than the police department. As with all forensic data, forensic toxicology data can not be expected to contain any amount of doubt from the collecting, transporting or analyzing of the sample. Because it is important to known how each laboratory is performing.

      Out of 17 laboratories, there was one missing report and one incomplete report. Some notable similarity in the correct results for the 15 laboratories that participated in the project, one of 15 laboratories reported quantitatively. The overall results from the reported laboratories were correct. Carefully review of the data reveals that young laboratory with less experiences reluctantly reported the result. The method utilized by laboratories were chemical, TLC, spectrophotometry, GC, HPLC , immunoassay and TDx. None of the laboratories need sophisticate equipment such as GC-MS for analyzing the sample.


References

1. ISO/IEC Guide 43-1, Proficiency Testing by Interlaboratory comparison Part 1. Development and Operation of Proficiency Testing Schemes, 1997.
2. Thomson M. International harmonized protocol for proficiency test of (chemical) analytical laboratories. J of AOAC International 76(4), 1993:926-940.
3. Basic Analytical Toxicology, World Health Organization, and Geneva: 1995.

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