Selective colorimetric detection of pentaerythritol tetranitrate (PETN) using arginine-mediated aggregation of gold nanoparticles.

Detection of pentaerythritol tetranitrate (PETN) as an explosive has been of great interest because of public safety and military concerns. Here, we have presented a simple, selective and sensitive colorimetric method for direct detection of PETN. The gold nanoparticles (AuNPs) were first exposed to arginine which has primary amines in its structure. Electron deficient -NH groups from arginine could strongly interact with -NO groups of PETN as electron donors. Hydrogen bonding happens between the -NO group of PETN and -NH group of arginine molecules. Therefore, selective aggregation of AuNPs happened because of the donor-acceptor and hydrogen bonding interactions. Due to the aggregation, the color of reddish AuNPs turned to blue or purple depend on PETN concentration. A good linear relationship was achieved between the aggregation signal (absorbance ratio of A/A) of the probe and the concentration of PETN with a limit of detection of 0.169 μmol L. Furthermore, we have found that the developed probe can detect PETN in complex matrices of groundwater and soil samples.