Background: The determination of trace drugs in aquatic environments is important. For
this purpose, many methods such as High Performance Liquid Chromatography (HPLC) and gas
chromatography mass spectrometry (GC/MS) have been used.
Objective: This study introduces a simple, sensitive, and rapid colorimetric method for the spectrophotometric
determination of sitagliptin (STG) in drinking water, tablet, human plasma, and human
urine using gold nanoparticles (AuNPs).
Methods: The Surface Plasmon Resonance (SPR) property of AuNPs and the interaction between
STG and AuNPs are the base of the colorimetric method. The addition of STG into AuNPs led to the
aggregation of AuNPs. Transmission Electron Microscopy (TEM) proved the aggregation of AuNPs
in the presence of STG. Also, the size of the nanoparticles distribution was evaluated by Dynamic
Light Scattering (DLS). In addition, Fourier-Transform Infrared Spectrophotometer (FTIR) was used
to study the chemical structure of AuNPs, STG, and AuNPs in the presence of STG.
Results: The parameters that affect the absorbance such as pH, type and volume of buffer, AuNPs
concentration, interaction time, ionic strength, and interfering ions were investigated and optimized.
Under the optimum conditions, the determination of STG was performed via this method over the
range of 50-300 μgL-1 (R2=0.9941) with the Limit of Detection (LOD) and Limit of Quantification
(LOQ) of 1.23 and 1.39 μgL-1, respectively.
Conclusion: Eventually, the results showed that the proposed method has a high potential for simple,
rapid, sensitive, and accurate determination of STG.