Background: Immunoassay is a laboratory technique that identifies and quantifies the antibody or the antigen in a sample by using the binding between an antigen and the homologous antibody. Using immunoassay techniques in forensic toxicological laboratories is very crucial since they are easy, sensitive and give preliminary results. Objectives: This study intends to cross-check the accuracy of three Immunoassay techniques Randox Evidence, Siemens V-Twin and Abbott Architect c-4000, as preliminary screening techniques for detection of drugs of abuse in urine by confirming the results using chromatographic techniques. A total of 919 random human urine samples were collected from the General Department of Forensic Sciences and Criminology in Dubai Police and run equally in all the three instruments known to be widely applied in the field of toxicology and forensic science laboratories across the world. They were checked for their capability and efficiency in screening drugs of abuse. Once the screening was done, the positive samples were confirmed for the detected drugs by using the extraction technique. The extracted samples were then analyzed for confirmation using Gas Chromatography-Mass Spectrometry and HPLC MS instrument where these drugs and their metabolites were identified. The results were then compared with the libraries database in the system hence confirming the study and its aim.
Results: The results of the study confirmed that all three instruments were capable of screening drugs of abuse but it also depends on the kits and the programs. It was seen that V-Twin and Architect c4000 showed almost similar results using EMIT but Randox which is using Biochip Array Technology was able to screen more varieties of drugs of abuse and their subclasses which were not detected in the screening with EMIT. Conclusion: The study concluded that Randox is the best screening accurate method for detection of drugs of abuse. Each of the three instruments has its own advantages and disadvantages as well as its maintenance technique, time is taken, and validity tests. Also, the confirmatory tests run after extraction in GC-MS and HPLC-MS should also be taken into consideration. This study can aid in directing the course of forensic casework.