Surface-enhanced Raman scattering and DFT investigation of Eriochrome Black T metal chelating compound

Novel nanosensor of cobalt(II) and copper(II) constructed from graphene quantum dots modified with Eriochrome Black T

Detection of heavy transition metals is of importance protecting humans and the environment from their toxicity. Amongst them, copper(II) and cobalt(II) need more attention due to their wide applications in industry, in which exposures with excess amounts of them cause heathy concerns. Hence, fast and efficient distinguishing copper(II) and cobalt(II) could be worthy. While electrochemical approaches could determine these cations, expensive instrumentation and time-consuming analysis are significant drawbacks, leading to concentrations on spectroscopic and colorimetric pathways. Herein, graphene quantum dot was modified with Eriochrome Black T (EBT) to generate a novel sensor with the ability of sensing mentioned cations. This new nanocompound demonstrated new optical properties when complexed with cobalt(II) in natural pH, and copper(II) in acidic media. Both cations successfully were detected by the new nanosensor through revealing distinct spectroscopic signals. Moreover, cobalt(II) was distinguished by this sensor colorimetrical, appearing green solution. Linear ranges of cobalt(II) and copper(II) were obtained as 0.02-0.08 M and 0.015-0.2 M, with the limit of detections 0.014 and 0.018 M, respectively.

Determination of Tetraethyl Lead in Gasoline fuel

  Tetraethyl lead TEL is an organometallic component that is added to gasoline to improve engine performance. This material is also called an anti-knock because it reduces the knocking of the engine. The engine starts to throttle if the oil in its pistons burns quickly or after a short period of time from entering it. In this study, a sensitive,  simple, economical, fast and accurate, an indirect spectral analytical method has been developed  using Eriochrome Black T as chelating agent without use of separation and  isolation to estimate the amount of lead in the gasoline by using UV-Visible spectrophotometer instrument. The accuracy and sensitivity of the method were 99.9067 ± 0.09 and 0.0338 while the limits of detection (LOD) and qualification (LOQ) were 0.0721 and    0.2186 μg ml-1 respectively. The developed method can be applied to water, biological, environmental and fuel sample.

SERS and DFT investigation of 1-(2-pyridylazo)-2-naphthol and its metal complexes with Al(III), Mn(II), Fe(III), Cu(II), Zn(II) and Pb(II)

The development of surface-enhanced Raman scattering (SERS) as a prospective analytical methodology for detection of metal ions was shown in recent years by several studies on metal complexes. In this work, 1-(2-pyridylazo)-2-naphthol (PAN) and its Al(III), Mn(II), Fe(III), Cu(II), Zn(II) and Pb(II) complexes were studied by FTIR, FT-Raman and surface enhanced Raman spectroscopies. Molecular geometry optimization, molecular electrostatic potential (MEP) distribution and vibrational frequencies calculations were performed using the hybrid B3LYP exchange-correlation functional for the PAN molecule and its bidentate complexes. The calculated MEP distributions indicated the atoms with highest electronegativity, the adsorption to the silver surface occurring through these atoms. Based on experimental and theoretical data we were able to identify unique and representative features, useful for the identification of each PAN-metal complex.