In this paper, a new electrochemical sensor was reported for the determination of amaranth in drink soft. In this sensor, activated carbon-Co3O4 nanocomposite (AC-Co3O4) was employ­ed as electrode modifying materials. The introduction of high pores to the activated carbon not only can in favor of more amaranth molecules adsorbed to the surface of the working electrode through the pores, but also may benefit fast electron diffusion in the electro­chemical detection process. So, the AC-Co3O4 modified electrode enhanced its electro­chemical signal obviously in the determination of amaranth  in drink soft and exhibited a wider linear response ranging from 0.1 to 215.0 µM with a low detection limit of 10.0 nM (based on 3Sb/m). This work offers a new route in developing new electro­chemical sensors for the determination of colorants additives and other hazard components in drink soft.

Tramadol is a centrally-acting analgesic used for treating moderate to severe acute and chronic pain. Pain is an unpleasant sensation that occurs most commonly as a result of tissue injury. Tramadol possesses agonist actions at the μ-opioid receptor and effects reuptake at the noradrenergic and serotonergic systems. In the last years, several analytical procedures have been published in the literature for the determination of tramadol from pharmaceutical formulations and biological matrices. Electrochemical methods have attracted tremendous attention for the quantification of this drug owing to their demonstrated potential for quick response, real-time measurements, elevated selectivity and sensitivity. In this review, we highlighted the recent advances and applications of nanomaterials-based electrochemical sensors for the analysis and detection of tramadol, which is extremely important for the indication of effective diagnoses and for quality control analyses in order to protect human health. Also, the main challenges in developing nanomaterials-based electrochemical sensors for the determination of tramadol will be discussed. At last, this review offers prospects for the future research and development needed for modified electrode sensing technology for the detection of tramadol.