A Novel Colorimetric Chemosensor Based on Ferene-S-Conjugated Silver Nanoparticles for Selective Recognition of Fe2+

Ferene is the most commonly used chromogenic agent for the determination of serum iron in blood. In this work we have successfully synthesized Ferene-S-conjugated silver nanoparticles (Ferene-S-AgNPs) for the first time characterized by UV-visible, Fourier-Transform Infrared Spectroscopy (FTIR), and Matrix-Assisted Laser Desorption/Ionization-Time Of Flight (MALDI-TOF) mass spectrometry techniques. Particle size of the synthesized nanoparticles was determined by atomic-force microscopy and scanning electron microscopy techniques with size ranges from 10–90 nm in diameter. Ferene-S-AgNPs were explored for their chemosensing potential with various metal ions such as Sb3+, Pb2+, Ca2+, Fe2+, K+, Co2+, Ba2+, V5+, Cu+, Cd2+, Hg2+, Ni2+, Cu2+, Fe3+, Mg2+, Mn2+, Al3+, and Cr3+. Ferene-S-AgNPs were found to show selective quenching effects and slight bathochromic shifts to the surface plasmon resonance absorption band after treatment with Fe2+. Furthermore, the developed chemosensor also exhibited substantial selectivity towards Fe2+ in the presence of other competitive ions. We observed that Ferene-S-AgNPs mimic the selectivity of the parent compound of Ferene towards Fe2+. The system obeyed Beer’s law over concentration ranges of 110–190 nM. The detection limit was found to be 110 nM.

Reversible Thermochromic Ink based on Crystal Violet Lactone/Boric Acid/Hexadecyl Alcohol for Anti-Counterfeiting Printing

The purpose of the study is to prepare reversible thermochromic materials with good discoloration properties, which are used as fillers to prepare a new type of reversible thermochromic ink. Reversible thermochromic materials were prepared by solid phase method with crystal violet lactone as chromogenic agent, boric acid as chromogenic agent and hexadecanol as cosolvent, and reversible thermochromic ink was prepared by using thermochromic material as filler. The scanning electron microscope images of reversible thermochromic materials showed that the prepared materials were spherical and had the advantages of non-adhesion. The printability of reversible thermochromic ink was discussed by changing the parameters including content of thermochromic material, printing pressure, ink sequence and using printability tester. The test of color change performance of thermochromic ink showed that the color change temperature range was 47.5–51.1 ◦ C, the color change time was 46 s, the recolor time was 29 s, and the stability was excellent. The reversible thermochromic ink has a certain application value in anti-counterfeiting printing.

Bromatometric Estimation of Irbesartan, Losartan, and Bisoprolol in Bulk and Tablet Forms: Statistical Analysis

A new spectrophotometric method is described for determination of irbesartan, losartan and bisoprolol in bulk and pharmaceutical dosage forms using insitu generated bromine as oxidizing agent and rhodamine B as chromogenic agent. Drugs are treated with known excess of bromine and residual unreacted bromine is determined by treating with fixed amount of rhodamine B then measuring absorbance at 557nm. The amount of bromine reacted corresponds to the amount of each drug. Effect of acidity, bromate-bromide volume and reaction time, on the absorption were studied. Calibration curves were linear over ranges of and for irbesartan, losartan, and bisoprolol, respectively. The method was satisfactory applied for the determination of drugs in both bulk and pharmaceutical forms and results were compared statistically with reference methods.

Spectrophotometric Determination of Calcium with Dibromo-p-methylsulfonazo

Calcium is a necessary trace element in the human body, and its low or high content in the human body is not appropriate. It is very meaningful to study the level of calcium in the human body and to determine calcium content in blood. As people take calcium through food, the determination of calcium content in certain tea and calcium supplements is of great significance. In this study, a new method for the determination of calcium was established using dibromo-p-methylsulfonazo as a chromogenic agent. In this article, the optimal conditions for the color reaction of Ca2+ with dibromo-p-methylsulfonazo were established. In a hydrochloric acid medium, Ca2+ and dibromo-p-methylsulfonazo form a blue complex. At 624 nm maximum absorption wavelength, the apparent molar absorptivity for the determination of calcium is 3.32 × 104 L·mol−1·cm−1. Beer’s law is applied for 0–0.60 μg/mL. The method has already been used in the determination of calcium in blood serum, whole blood, tea leaf, and calcium fudge with satisfactory results.

A novel colorimetric immunoassay based on enzyme-regulated instant generation of Turnbull's blue for the sensitive determination of ochratoxin A

The aim of this study was to develop a novel colorimetric sensing method based on enzyme-regulated instant generation of Turnbull's blue, serving as a chromogenic agent, for a sensitive immunoassay for the determination of ochratoxin A (OTA).

Peroxidase-like activity of acetylcholine-based colorimetric detection of acetylcholinesterase activity and an organophosphorus inhibitor

Colorimetric detection of acetylcholinesterase (AChE) and its inhibitor organophosphates (OPs) is attractive for its convenience, but the addition of exogenous catalyst to produce a chromogenic agent may result in complexity and interference.

A low cost and rapid analytical technique for direct spectrophotometric determination of chromium in V–Cr–Ti alloys without a chromogenic agent

A simple, rapid and accurate spectrophotometric method was developed for the determination of chromium in V–Cr–Ti ternary alloy without any prior separation and chromogenic agent.