ABSTRACT
Cellulose acetate is derived from cellulose and has the characteristics of biodegradability and reusability. So, it has been used for the elimination of toxic compounds capable of producing different diseases, such as cadmium, that result from human and industrial activity. For this reason, capsules functionalized with Cyanex 923 were prepared and characterized by FTIR spectroscopy, Energy Dispersive X-ray Spectroscopy (EDX), and SEM. The functionalized capsules were used for removing and recovering Cd(II) by modifying variables such as HCl concentration in the extraction medium and carrier content in the capsules, among others. The extraction of cadmium from battery leachates and the three isotherm models, Langmuir, Freundlich, and Dubinin Radushkevich, were also tested to model the cadmium removal process. The results showed a favorable physical sorption with a good capacity for extraction and the possibility of reusing the capsules for up to seven cycles without a decrease in the percentage of cadmium recovery.
ABSTRACT
Since lead is a highly toxic metal, it is necessary to detect its presence in different samples; unfortunately, analysis can be complicated if the samples contain concentrations below the detection limit of conventional analytical techniques. Solid phase extraction is a technique that allows the carrying out of a pre-concentration process and thus makes it easy to quantify analytes. This work studied the efficiency of sorption and preconcentration of lead utilizing polysulfone (PSf) fibers grafted with acrylic acid (AA). The best conditions for Pb(II) extraction were: pH 5, 0.1 mol L-1 of ionic strength, and 40 mg of sorbent (70% of removal). The sorbed Pb(II) was pre-concentrated by using an HNO3 solution and quantified using flame atomic absorption spectrometry. The described procedure was used to obtain a correlation curve between initial concentrations and those obtained after the preconcentration process. This curve and the developed methodology were applied to the determination of Pb(II) concentration in a water sample contained in a handmade glazed clay vessel. With the implementation of the developed method, it was possible to pre-concentrate and determine a leached Pb(II) concentration of 258 µg L-1.
ABSTRACT
In this work a simple and novel procedure for leucomalachite green determination based on micro flow injection analysis (µFIA) with amperometric detection is presented. The method involves the use of henequen modified fibers as microfluidic channels. The µFIA system proposed offers a simple, rapid, and low-cost alternative for the determination. Capillary and gravitational forces across the modified henequen fibers control the flow rate, eliminating the need for external pumps. This technique requires low reagent consumption and allows portability for in situ measurements. The flow system is described, and the operational variables were studied and optimized using a Taguchi parameters design to increase analytical sensitivity. Under optimal conditions a limit of detection of 1.16 µg kg-1 was achieved with adequate repeatability and reproducibility (expressed as %RSD <5.0%, n = 3, n = 9 respectively) in all cases. The effect of interfering species and the accuracy of the method were also investigated. The proposed methodology was validated and applied to determine LMG in tilapia muscle samples.
ABSTRACT
A method using UV-Vis spectroscopy and multivariate tools for simultaneous determination of glucose and cholesterol was developed in this paper. The method is based on the development of the reaction between the analytes (cholesterol and glucose) and enzymatic reagents. The spectra were analyzed by partial least squares regression and artificial neural networks. The precision estimated between nominal and calculate concentration demonstrate that artificial neural network model was adequate to quantify both analytes in serum samples, since the % relative error obtained was in the interval from 5.1 to 8.3. The proposed model was applied to analyze blood serum samples, and the results are similar compared to those obtained employing the reference method.
