The use of outer filter effects for Cu²⁺ quantitation: a unique example for monitoring nonfluorescent molecule with fluorescence

Abstract

This article concerns a new and precise strategy for the determination of Cu(2+) based on a color reaction and outer filter effects (OFEs). Cu(2+) can react with sodium diethyldithiocarbamate trihydrate (DDTC) to form a DDTC-Cu(2+) complex with a significant absorption at 447 nm. Being positively correlated with Cu(2+), the absorption could be treated as the basis for the determination of Cu(2+). When cuvettes containing the complex were fixed in the light path of a fluorescence spectrophotometer, the excitation/emitted light were absorbed by the OFEs, similar to absorption mechanisms of inner filter effects. Under suitable conditions, OFEs from the complex could quantitatively reduce the fluorescence intensities of quinine sulfate and acridine yellow by absorbing the excitation or emission light. Compared with traditional absorption spectroscopy (with a detection limit at 0.9 µmol/L), indirect OEF techniques showed increased sensitivities by about 1 order of magnitude. The strategy could be extended to many different systems where components absorb the excitation wavelength and/or emission wavelength of fluorescers.

Development of Hollow Gold Nanoparticles for Photothermal Therapy and Their Cytotoxic Effect on a Glioma Cell Line When Combined with Copper Diethyldithiocarbamate

“…Regarding the light absorbance of DDTC-Cu, it had peaks around 447 nm and UV region (< 300 nm). 44) Thus, we consider that the influence of NIR-laser on the DDTC-Cu is minimum.…”

Spectroscopic Investigations on the Interaction between Carbon Nanotubes and Catalase on Molecular Level

“…The IFE from ligand refers to the absorbance or optical dispersion of light at the emission wavelength of the fluorescer [18]. MWCNTs can quench the fluorescence signal of the protein.…”

“…However, the absorbance of the system will be increased with the concentration of the protein-MWCNTs complex, which causes the inner filter effect (IFE). The IFE from ligand refers to the absorbance or optical dispersion of light at the emission wavelength of the fluorescer [18]. MWCNTs can quench the fluorescence signal of the protein.…”

A Low-Cost Colorimetric Assay for the Analytical Determination of Copper Ions with Consumer Electronic Imaging Devices in Natural Water Samples

“…In terms of analytical chemistry, a vast number of recent analytical methods have been developed and validated for the quantification of Cu 2+ in several samples, including biochemical, food, water, and wastewater samples. These methods are mainly spectroscopic and require expensive instrumentation and specialized staff, including batch UV-Vis spectrometry [ 11 , 12 , 13 , 14 ], flame atomic absorption spectroscopy (FAAS) [ 15 , 16 , 17 , 18 ], graphite furnace atomic absorption spectrometry (GFAAS) [ 19 , 20 ], inductively coupled plasma (ICP) [ 21 , 22 ], flow injection [ 23 ], and fluorescence [ 24 , 25 , 26 , 27 ].…”