Green Silver Nanoparticle for Colorimetric Determination of Cyanide in Water Samples

Cyanide ion is highly toxic to human. Cyanide ion is mainly used in processes like electroplating and extraction of silver and gold. Therefore, it can enter the environment and pollute soil and water. In the present work, a colorimetric method based on silver nanoparticle (AgNP) was proposed for detection and determination of cyanide ion. Silver nanoparticle was prepared by carbon dots as reducing agent. Volume of AgNP and concentration of sodium hydroxide were optimized for determination of cyanide ion by AgNP. It was observed that greenly synthesized AgNP can serve as reagent in detection and determination of cyanide ion. In the presence of sodium hydroxide, a method was optimized and a robust model with linear range of 4.0-100.0 μM, limit of detection of 3.8 μM and limit of quantification of 12.7 μM was obtained. In the method presented, the color change of AgNP from yellow to colorless in the presence of cyanide ion was observed. Environmental water samples including spring, well and wastewater were successfully analyzed by this method, which is simple and inexpensive

Coupling Second-Order Excitation-Emission Spectrofluorimetric Data with Standard Addition method to Quantify Carvedilol in Real Samples

Prediction using pure standards is expected to be biased whenever the slope of the calibration is affected by the presence of sample matrix. Moreover, in the presence of unknown spectral interferents, first-order algorithms like partial least squares cannot be used. In this study, a method for determination of carvedilol (CAR) in tablet and urine samples is proposed by excitation-emission fluorescence spectroscopy (EEM). The multivariate curve resolution-alternating least-squares (MCR-ALS) coupled with trilinearity constraint exploiting the second order advantage is applied for the analysis of EEMs. Moreover, the combination of standard addition with MCR-ALS was used to correct the matrix effect. Indeed, by the proposed strategy, both matrix effect and the problem of the presence of unknown interferents in determination of CAR are overcome.       The MCR-ALS method was applied on EEMs under non-negativity and trilinearity constraints. For both samples, CAR was quantified at low mg l-1 level with an overall prediction error of -3.1% and -4.0% in urine and tablet samples, respectively

Response Surface Methodology in Spectrophotometric Determination of Formaldehyde Using Ch romotropic Acid

Formaldehyde in small quantities is commonly analyzed by spectrophotometric methods. One of the most-commonly used spectrophotometric techniques for this purpose is based on the reaction with chromotropic acid. Because of its simplicity, sensitivity, selectivity and its low cost, it is still widely used. Investigations for replacing the concentrated sulfuric acid with other acids or using more dilute solutions of sulfuric acid have been performed. Herein, spectrophotometric determination of formaldehyde by chromotropic acid in the sulfuric acid medium is explored and modified by response surface methodology. The reaction was monitored by measuring the absorbance of the product at 574 nm. The factors affecting the response, i.e. concentration of sulfuric acid and concentration of chromotropic acid, were explored and optimized using response surface methodology. The calibration curve was linear in the range of 0.03-7.00 mg l-1 with detection limit of 0.005 mg l-1. The method was found to be sensitive, selective and was applied to determine the formaldehyde in toothpaste, clothing softener and acetic acid samples with satisfactory results