Built-up analytical procedures, manufacture of home-made sensor and controlled instrument for detection of Hg(II) in trace level in aqueous environment. This creates a premise for self made instruments, meeting reality requirements in our country.

Theoretical results:

• Studied electrochemical techniques to prepare gold nanoparticles with different morphologies, such as density, size, assembly or coverage on the glassy carbon electrode surface. These characteristics are meaningful in fabricating electrochemical and biosensors for improving obtained signals.
• Investigated thiol compounds that are applicable to fabricate sensors having nanostructure for Hg(II) detection. Of those, 4-pyridinethanethiol was selected as a major component for the aim of the project.
• Employed 4-pyridinethanthiol to modify gold nanoparticles on glassy carbon surface resulted in enhancing sensitivity, diminishing the limit of detection to ppt level.
• It was found optimized conditions for operation of the sensor in detection of Hg(II).
• Discovered capability of self-assembled monolayers (SAM) composed of 4-pyridinethanethiol and 2-aminoethanethiol in improving sensitivity of Hg(II) detection. The study indicated typical characteristics of this binary SAMs. This is very useful for preparing the binary SAMs to improve sensitivity of Hg(II) detection.

Applied results: The sensor and instrument were employed to determine Hg(II) in samples of seawater, surface water and wastewater in laboratory as well in the field. Obtained results showed that home-made sensor and instrument can detect Hg(II) in few tens ppt level in different types of water sample. This indicates that the sensor and instrument can be used for effectively fast detection of Hg(II) pollution, supporting to the environmental impact assessment and treatment become further effectiveness.

Novelty of the results:

• This is the first time, SAM of 4-pyridinethanethiol modified gold nanoparticles on glassy carbon electrode was used to fabricate electrochemical sensor for Hg(II) detection in ultra trace level.
• This is the first time, the home-made sensor and instrument were used to detect Hg(II) on-site.
• This is the first time, the binary SAMs prepared by method of two separated adsorption steps was studied to improve the sensitivity of Hg(II) detection.

Actuality meaningfulness of the results: The obtained results of the project indicated the method of using sensor and instrument is feasible for detection of Hg(II) at ultra low level on-site.

Scientific meaningfulness of the results: The obtained results indicated that home-made sensor provided wide linear range and the limit of detection at ultra trace level can be employed. This reveals that use of electrochemical sensors for on-site detection of heavy metal ions at ultra trace concentrations can be feasible, reduces analysing time and cost. It can support for pollution monitoring activities in water resources.