Visual and Optical Absorbance Detection of Melamine in Milk by Melamine-Induced Aggregation of Gold Nanoparticles.

The present study reported a facile method for the determination of melamine in milk powder products based on the aggregation of reactant-free 5 nm gold nanoparticles (AuNPs). The strong electrostatic attraction between the positively charged exocyclic amine groups present in the melamine molecule and the negatively charged ions bound to the AuNPs induced aggregation of the AuNPs, resulting in visible color changes that could be seen with the naked eye and monitored by ultraviolet-visible (UV-Vis) absorbance spectra. The method shows high sensitivity with detection limits of 1 × 10 M for visual detection and 1 × 10 M for UV-Vis analysis, which is far below the safety limit of melamine ingestion in infant formula (1 ppm = 7.

Optimization and Analytical Behavior of Electrochemical Sensors Based on the Modification of Indium Tin Oxide (ITO) Using PANI/MWCNTs/AuNPs for Mercury Detection.

In the present study, indium tin oxide (ITO) was used as a transparent working electrode for the development of an electrochemical sensor for the detection of mercury (II) ions (Hg). The electrode was modified by direct electrodeposition of polyaniline (PANI), multiwalled carbon nanotubes (MWCNTs) and gold nanoparticles (AuNPs) followed by optimization of the analyte and operating conditions, aiming to improve the selectivity, sensitivity and reliability of the electrode for mercury detection. Successful immobilization of the PANI and nanomaterials (MWCNTs and AuNPs) on the ITO electrode was confirmed by Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) and Fourier Transform Infrared Spectroscopy (FTIR) analyses.

Development of Formaldehyde Biosensor for Determination of Formalin in Fish Samples; Malabar Red Snapper (Lutjanus malabaricus) and Longtail Tuna (Thunnus tonggol).

Electrochemical biosensors are widely recognized in biosensing devices due to the fact that gives a direct, reliable, and reproducible measurement within a short period. During bio-interaction process and the generation of electrons, it produces electrochemical signals which can be measured using an electrochemical detector. A formaldehyde biosensor was successfully developed by depositing an ionic liquid (IL) (e.