New turn on fluorimetric sensor for direct detection of ultra-trace ferric ions in industrial wastewater and its application by test strips

A naphthol hydrazone Schiff base bearing benzothiadiazole unit for fluorescent detection of Fe3+ in PC3 cells

Naphthol hydrazone derivatives are recognized as efficient chelating agents for both qualitative and quantitative detection of metal ions. Here we design a naphthol hydrazine-based chemosensor with covalently linking a strong electron-withdrawing benzothiadiazole group to modulate the molecular electronic structure, nominated as NtHzBtd. The fluorescent probe performs excellent selectivity and sensitivity towards Fe³⁺ with 1:1 binding stoichiometry, while exhibiting a quick response at 55 s with a relatively low limit of detection of 0.036 µM. A series of spectroscopic measurements in tandem with theoretical calculations suggest that the probe undergoes both intramolecular charge transfer (ICT) and chelation enhanced quenching (CHEQ) processes. Successful color rendering of paper strips and bioimaging in PC3 cells demonstrate the promising applicability of NtHzBtd for portable Fe³⁺ detection in real samples and biosystems.

New nano materials-based optical sensor for application in rapid detection of Fe(II) and Pd(II) ions

For the analytical determination of Fe(II) and Pd(II) concentrations, a novel optical sensor based on spectrophotometric technique was used. The optical sensor was prepared by direct immobilization of a novel synthesized chromophore, 5-amino-phenanthrolin-3 formyl salicylic acid, onto nanocellulose. Human vision can identify the color associated with Fe II ions, and spectrophotometric methods can measure it with detection and quantification limits of 0.239 and 0.796 ppb, respectively. Pd(II) detection and quantification limits were 0.318 ppb and 1.06 ppb, respectively. The effects of various parameters on the detection of Fe(II) or Pd(II) ion content were investigated and optimized. The optical phenanthroline-nanocellulose (5-Phen) sensor could be reproduced multiple times and used with a higher capacity each time. The results demonstrated that the 5-Phen sensor could measure Fe(II) in human blood serum accurately and successfully even without any pre-concentration.

High-throughput sensor microtiter plate of new terbium complexes for the determination of anthracene in seawater

A new fluorescent sensing microtiter plate (MTP) was developed for high sensitivity monitoring of anthracene in seawater samples. For this purpose, two ternary complexes of Tb(III) ions with dibenzoylmethane and neocuproine [Tb(DBM)₂(MePhen)] or with dibenzoylmethane and bathocuproine [Tb(DBM)₂(PhMePhen)] were synthesized. Elemental analysis, energy dispersive X-ray analysis, X-ray diffraction, infrared and ultraviolet-visible emission, and thermal analysis were conducted on the Tb(III) complexes. The limits of detection (D_L) were 0.14 and 1.05 μmol L^-1 for [Tb(DBM)₂(MePhen)] and [Tb(DBM)₂(PhMePhen)], respectively. [Tb(DBM)₂(PhMePhen)] MTP is embedded in a membrane made of cellulose acetate. The first high-throughput anthracene sensor MTP, based on [Tb(DBM)₂(PhMePhen)] sensor showed a linear range, from 0.2 to 20 μmol L^-1. [Tb(DBM)₂(PhMePhen)] MTP was validated for accurate and precise monitoring of anthracene using gas chromatography. The selectivity of the [Tb(DBM)₂(PhMePhen)] MTP toward anthracene was examined. The data indicated that [Tb(DBM)₂(PhMePhen)] MTP is suitable for rapid and direct detection of anthracene.

Spot tests: past and present

Microchemistry, i.e., the chemistry performed at the scale of a microgram or less, has its roots in the late eighteenth and early nineteenth centuries. In the first half of the twentieth century a wide range of spot tests have been developed. For didactic reasons, they are still part of the curriculum of chemistry students. However, they are even highly important for applied analyses in conservation of cultural heritage, food science, forensic science, clinical and pharmacological sciences, geochemistry, and environmental sciences. Modern pregnancy tests, virus tests, etc. are the most recent examples of sophisticated spot tests. The present ChemTexts contribution aims to provide an overview of the past and present of this analytical methodology.