A cost effective hydrogel test kit for pre and post blast trinitrotoluene.
A cost effective hydrogel test kit was successfully developed for the detection of pre- and post-blast trinitrotoluene (TNT). A polyvinyl alcohol (PVA) hydrogel matrix was used to entrap the potassium hydroxide (KOH) colourimetric reagent. The easily portable test kit was fabricated in situ in a small tube to which the sample could be added directly. The test kit was used in conjunction with digital image colourimetry (DIC) to demonstrate the rapid quantitative analysis of TNT in a test soil sample. The built-in digital camera of an iPhone was used to capture digital images of the colourimetric products from the test kit. Red-Green-Blue (RGB) colour data from the digital images of TNT standard solutions were used to establish a calibration graph. The validation of the DIC method indicated excellent inter day precision (0.12-3.60%RSD) and accuracy (93-108% relative accuracy). Post-blast soil samples containing TNT were analysed using the test kit and were in good agreement with spectrophotometric analysis. The intensity of the RGB data from the TNT complex deviated by +6.3%, +5.1%, and -4.9% after storage of the test kits in a freezer for 3 months. The test kit was also reusable for up to 12 times with only -5.4%, +0.3%, and +4.0% deviations. The hydrogel test kit was applied in the detection of trace explosive residues at the scene of the recent Bangkok bombing at the Ratchaprasong intersection and produced positive results for TNT demonstrating its operational field application as a rapid and cost effective quantitative tool for explosive residue analysis.
Applied Chemistry and Environmental Technology Research Center, Andaman Environmental Research and Innovation Center, Faculty of Technology and Environment, Prince of Songkla University, Phuket Campus, Kathu, Phuket 83120, Thailand. Electronic address: choodum@gmail.com.
Aree
A
Choodum
Department of Applied Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
Khanitta
K
Malathong
Centre for Anatomy and Human Identification, School of Science and Engineering, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
Niamh
N
NicDaeid
Applied Chemistry and Environmental Technology Research Center, Andaman Environmental Research and Innovation Center, Faculty of Technology and Environment, Prince of Songkla University, Phuket Campus, Kathu, Phuket 83120, Thailand.
Wadcharawadee
W
Limsakul
Applied Chemistry and Environmental Technology Research Center, Andaman Environmental Research and Innovation Center, Faculty of Technology and Environment, Prince of Songkla University, Phuket Campus, Kathu, Phuket 83120, Thailand; Center of Excellence for Hazardous Substance Management (HSM), Bangkok 10330, Thailand; Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
Worawit
W
Wongniramaikul
Digital images; Hydrogel; Red Green Blue colour system; Trinitrotoluene; iPhone