Serum albumins, as the major soluble protein constituents of the circulatory system, have many physiological functions. Quantification of albumin is clinically important, especially in low concentration is of great significance and is routinely measured by UV spectroscopy. However, these methods tends to overestimation, and more critically, depends highly on the timing, protein variation and suffer from interference in the measurements. Here, to overcome these difficulties, we report a simple, time-insensitive and superior sensitive method based on a binding of a new cationic cyanine dye with BSA under a spectrophotometric and image analysis technique that can be used as a sensor to quantify BSA. This method is more convenient because it allows for UV spectroscopy measurements during a>25 min period. Optimum conditions for the determination of BSA were also investigated by experimental design method. The linear ranges for BSA are 22.00 -112.00 nM and 0.43-4.10 mM and limits of detection is 6.25 nM. The relative standard deviation of six replicate measurements was 2.33% for 2.50 mM BSA. This method is simple, practical, and relatively free interference from coexisting substances and can be successfully applied to determination of HSA in urine sample.

This study introduces a simple, cost-effective, and highly sensitive colorimetric method for detecting and quantifying Sildenafil Citrate based on the aggregation of citrate-coated silver nanoparticles (AgNPs). The AgNPs were synthesized through the reduction of silver nitrate with sodium borohydride. Under optimized conditions, the presence of Sildenafil Citrate induces a distinct color change in the AgNP solution from light yellow to red, proportional to the Sildenafil Citrate concentration. This aggregation causes a decrease in the localized surface plasmon resonance (LSPR) absorbance at 394 nm and the emergence of a new peak at 530 nm. A linear correlation was established between the Sildenafil Citrate concentration and the absorbance ratio (A530/A394) in the range of 0.34–3.1 µM, with an impressive detection limit of 0.005 µM. The method was successfully applied to quantify Sildenafil Citrate in pharmaceutical tablets, demonstrating high accuracy, excellent stability, and practical applicability for quality control in health products.

The measurement of antibiotics is of great importance. Therefore, in this research, a colorimetric sensor based on the reaction of ferric iron and norfloxacin and the formation of a black complex resulting from their reaction has been designed. For this purpose, all conditions were optimized using a one-factor-at-a-time method to achieve the highest sensitivity. Then, under optimal conditions (pH=3.0, contact time 60 seconds, iron concentration 100 ppm), the designed sensor showed a suitable linear range from 1 to 100 micromolar. The detection limit and quantification limit are 0.31 and 0.99, respectively. In the developed method, a smartphone and the analysis of green, red, and blue colors from the captured images were used as the analytical signal, thus the developed method also benefits from portability and low cost. Finally, the proposed method was used for the analysis of norfloxacin in three wastewater samples, and the results were compared with a standard method.

A selective, simple and low-cost method for the colorimetric determination of Fe3+ ions based on chitosan capped silver nanoparticles (Chit-AgNPs) is presented. Chitosan is a cationic polyelectrolyte possessing amino and hydroxy groups which make it widely used as a capping agent for Ag NPs. The synthesized chitosan capped silver nanoparticles with excellent colloidal stability were characterized by UV-Vis spectrometry, transmission electron microscopy, Fourier transform infrared, and X-ray diffraction. Chit-AgNPs exhibit a strong surface plasmon resonance band which disappears in the presence of increasing concentrations of Fe3+ ions. This system showed a visually detectable color change from brownish-yellow to colorless for the selective determination of Fe3+. The method can be applied for the determination of Fe3+ ions in the concentration range of 1. 0 × 10-6-5. 0 × 10-4 M. The detection limit was determined from three times the standard deviation of the blank signal (3σ /slope) as 5. 3 × 10-7 M. The developed method was successfully applied for the determination of Fe3+in real samples.

Spectral images are the most valuable data than can be achieved using 2D sensors. Spectral estimation using data with a few channel cameras has been the subject of many studies. It is common to use color filters in front of the lens for increasing dimensionality of data. However, spectral estimations are prone to suffer from colorimetric errors. To address this problem it was shown that this problem is a special case of error-free spectral estimation problem. Considering the fact that most of RGB cameras tend to be colorimetric, using geometrical modeling of the problem, it was shown that adding a shoot with bare lens to the sensor’ s data can solve the problem. The notion has been tested in different scenarios and the efficiency of the proposed method has been proved in the scenarios. Results showed that if the camera is acceptably colorimetric, the proposed method can even leads to error-free colorimetric performance. Prog. Color Colorants Coat. 13 (2020), 121-130© Institute for Color Science and Technology.