Determination of ketamine using melamine-modified gold nanoparticles.

Ketamine is used in medicine because of its anaesthetic and antidepressant effects at low doses. Unfortunately, due to its narcotic effect when used at high doses, its abuse among young people is increasing. It is also one of the most common drugs used in rape. Therefore, there is a need for fast and inexpensive tests that can be performed on-site. With the advancement of nanotechnology, nanoparticle-based approaches have found their place in selective analyses as in many fields. In the developed method, firstly gold nanoparticles were modified with melamine (AuNPs@Mel). Under optimized conditions, hydrogen bonds formed between ketamine and AuNPs@Mel cause the red colour of AuNPs@Mel to shift to blue-purple (i.e. aggregation-induced surface plasmon absorption shift). The association between absorbance and concentration produced a calibration line (curve) having a linearity correlation coefficient of 0.9981 for ketamine concentrations ranging from 4.76 to 47.6 mg L. The detection limit of the proposed method was 1.5 mg L and the RSD (relative standard deviation) values of concentrations were changed ranging from 5.2% to 8.2%. The intra-assay and inter-assay measurements using the suggested method resulted in coefficients of variation (CVs) of 5.7% and 8.5%, respectively. Scan transmission electron microscopy (STEM), UV-vis spectrophotometry and FTIR spectroscopy were used to characterize the synthesized and modified AuNPs. Additionally, the procedure was successfully carried out with some interference materials and a real sample of fetal bovine serum. Lastly, using the Student t-test and F tests, the suggested technique was compared to and confirmed against an LC-MS/MS procedure previously published.